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Postweaning substitution of grazed forage with a high-energy concentrate has variable long-term effects on subcutaneous fat and marbling in Bos taurus genotypes
Abstract
The objective of this study was to quantify the effects and interactions of stage of growth and genotype on commercial carcass traits and intramuscular fat (IMF) content in 5 muscles of Bos Taurus steers (n = 165) and to test the hypothesis that substituting pasture with a high-energy concentrate during the immediate postweaning period increases IMF. Cattle of 3 genotypes (Angus, Hereford, and Wagyu × Angus; n = 55/genotype) were selected at weaning from commercial herds, targeting genotypic differences in marbling and subcutaneous fatness. Following weaning, steers were fed for 168 d within 2 different improved, temperate pasture-based nutritional systems: a forage-only system (FS) and forage with high-energy supplemented system (SS), with 2 replicates per system. The supplement was fed at a level of 1% of average BW adjusted every 2 wk to provide an estimated 50% of energy requirements for 168 d from weaning. Pasture on offer in both systems was managed to match the BW of the FS and SS steers during the postweaning treatment period to avoid confounding due to differences in growth rate during this period. Steers were then regrouped into 2 replicates and backgrounded on improved, temperate pasture for 158 d and then grain fed within 1 group for 105 d (short fed) or 259 d (long fed). Groups were slaughtered at commencement (d 0) and end of postweaning nutritional treatments (d 168), end of backgrounding (d 326), and after short (d 431) or long feedlotting (d 585). Serial slaughter stage had an effect on all traits assessed (P < 0.01). The FS steers had more rib fat (P < 0.01) and higher Meat Standards Australia marbling score (P < 0.05) and a tendency (P < 0.10) to have greater eye muscle area than the SS steers throughout the study. Genotypic differences were evident (P < 0.05) for all traits assessed except HCW, dressing percentage, rib fat depth, ossification score, ultimate pH, and IMF in the semitendinosus muscle. The results for marbling and IMF do not support the use of a high-energy feed as a substitute for an equivalent amount of energy from pasture during the immediate postweaning period to enhance development of marbling.
... Traits such as marbling score (or intramuscular fat content), subcutaneous fat depth and retail beef yield (RBY) having significant economic impacts for beef producers and across the beef supply chain. The proportion of muscle, bone and fat in beef carcasses differs widely as a result of the stage of maturity, genotype and nutrition (Oddy et al. 2001;Greenwood et al. 2015). These factors may also influence the potential to use ultrasound measurement systems in live cattle to predict carcase traits. ...
... It was hypothesised that ultrasound measurements of fatness and muscle made earlier in the life of cattle can predict later-life carcase characteristics. To test this hypothesis, relationships between intramuscular fat, subcutaneous fat and eye-muscle (Longissimus thoracis et lumborum) cross-sectional area measurements made using ultrasound, and carcase fatness, muscling and yield measurements made following slaughter of Bos taurus steers that differed genetically in potential for subcutaneous fatness and marbling, were assessed (Greenwood et al. 2015). The cattle were assessed by ultrasound at six stages of growth, and carcase measurements were made at five stages of growth, from weaning through to long-feedlotting. ...
... Animal breed, estimated breeding value differences and marbling sire lines were criteria used to identify cattle suitable for the experiment. Detailed information on the animals, including their genetics, nutrition, management, liveweights and carcase measurements, were provided by Greenwood et al. (2015). ...
Context Identification earlier in life of beef cattle with capacity for increased marbling, improved carcase yield and/or reduced subcutaneous fatness can facilitate more rapid genetic improvement and identification of cattle more appropriate for feedlot or pasture finishing. Earlier in life, ultrasound predictions have potential for significant improvements in compliance with market specifications and overall efficiency of beef production systems. Aims To assess the relationships just prior to slaughter and earlier in life between measurements of intramuscular fat, subcutaneous fat and eye-muscle (Longissimus thoracis et lumborum) cross-sectional area made using ultrasound, and carcase fatness, muscling and yield measurements following slaughter of Bos taurus steers that differed genetically in potential for subcutaneous fatness and marbling. Methods Ultrasound measurements of intramuscular fat (IMF), rib fat (RFT), P8 rump fat (P8FAT), eye-muscle area (EMA) and retail beef yield (RBY) of cattle heterogeneous for marbling and fat distribution were made at six stages of growth from weaning to long-feedlotting. Carcase measurements of the same traits were made at five stages of growth from weaning through to long-feedlotting. Key results IMF ultrasound scans 168 days post-weaning were more strongly correlated (r ≤ 0.79) with marbling in the carcase following long-feedlotting than were IMF ultrasound scans at the end of backgrounding (r ≤ 0.71, 326 days post-weaning), short-feedlotting (r ≤ 0.69, 431 days) and during (r ≤ 0.59, 521 days) and at the end of long-feedlotting (r ≤ 0.53, 585 days). P8FAT was the trait with the highest and most consistent accuracy across all stages of life (r = 0.80) between ultrasound and carcase measurements of P8FAT. Conclusions The results of the present study showed that ultrasound-scanned measures of carcase IMF, subcutaneous fat and EMA can be used to predict carcase characteristics with good accuracy earlier in life. Implications The finding that prediction of marbling in the carcase of long-feedlot-fed cattle was stronger by using ultrasound measurement of IMF in younger post-weaned cattle than in older post-weaned cattle warrants further investigation for genetic improvement and management applications, including using newer scanning technologies.
... Bos taurus cattle generally have higher IMF contents than Bos indicus cattle (Teixeira et al., 2017, Flowers et al., 2018. For instance, the IMF content of Hereford (8.3%) (Greenwood et al., 2015) and Angus (6.5-7.5%) (Liu et al., 2021, Detweiler et al., 2019 is higher than that of Brahman and Nellore, which is mostly lower than 5% (Cesar et al. 2014, Miguel et al. 2011. ...
... The IMF content of the LM in Wagyu steers increased from 23.7% at 20 months old to 41.1% at 30 months old (Okumura et al., 2012). Greenwood et al. (2015) also observed increased IMF contents in Angus, Hereford, and Wagyu-×Angus cattle when their slaughter age increased. Additionally, Holstein-Friesian bulls slaughtered 26 months of age had higher IMF content than those slaughtered at 20 months of age . ...
... Moreover, Nogalski et al. (2014) found that the IMF content of the LM in both Holstein×Limousin bulls and steers significantly increased when their slaughter weights increased from 450 to 600 kg. Similar results in Angus, Wagyu×Angus and Hereford cattle also were reported (Bruns et al., 2004, Greenwood et al., 2015. ...
The content of intramuscular fat (IMF), that determines marbling levels is considered as one of the vital factors influencing beef sensory quality including tenderness, juiciness, flavour and colour. The IMF formation in cattle commences around six months after conception, and continuously grows throughout the life of the animal. The accumulation of marbling is remarkably affected by genetic, sexual, nutritional and management factors. In this review, the adipogenesis and lipogenesis process regulated by various factors and genes during fetal and growing stages is briefly presented. We also discuss the findings of recent studies on the effects of breed, gene, heritability and gender on the marbling accumulation. Various research reported that feeding during pregnancy, concentrate to roughage ratios and the supplementation or restriction of vitamin A, C, and D are crucial nutritional factors affecting the formation and development of IMF. Castration and early weaning combined with high energy feeding are effective management strategies for improving the accumulation of IMF. Furthermore, age and weight at slaughter are also reviewed because they have significant effects on marbling levels. The combination of several factors could positively affect the improvement of the IMF deposition. Therefore, advanced strategies that simultaneously apply genetic, sexual, nutritional and management factors to achieve desired IMF content without detrimental impacts on feed efficiency in high-marbling beef production are essential.
... The objective of the present study was to test the extent to which WBSF of meat from varying Bos taurus breed types (Angus, Hereford and Wagyu · Angus) and ages/feeding phase (6, 17 and 25 months corresponding to weaning, end of backgrounding at pasture and end of feedlotting, respectively) of cattle is related to those traits assessed by Rhee et al. (2004), namely sarcomere length, collagen content and desmin degradation, or whether more variation in WBSF is explained by inclusion of solubility of collagen, IMF content and ultimate pH in statistical analyses. Carcass characteristics of these steers are presented in Greenwood et al. (2015). ...
... The meat samples from the animals used in the present study originated from the experiment described by Greenwood et al. (2015). They included samples from steers of three breed types (Angus, Hereford, and Wagyu · Angus) varying in capacity for accretion of fat depots and three age/feeding phase groups (6, 17 and 25 months) from slaughter stages 1 (weaning), 3 (end of backgrounding at pasture) and 5 (end of longfeedlotting) in Greenwood et al. (2015). ...
... The meat samples from the animals used in the present study originated from the experiment described by Greenwood et al. (2015). They included samples from steers of three breed types (Angus, Hereford, and Wagyu · Angus) varying in capacity for accretion of fat depots and three age/feeding phase groups (6, 17 and 25 months) from slaughter stages 1 (weaning), 3 (end of backgrounding at pasture) and 5 (end of longfeedlotting) in Greenwood et al. (2015). Five steers of each breed type were slaughtered at weaning (age 6 months in March 2009), 10 steers of each breed type were slaughtered at the end of 326 days backgrounding (age 17 months in January 2010), and 10 steers of each breed type were slaughtered following 259 days of feedlotting (age 25 months in October 2010). ...
Context. The texture of beef is highly important for the eating experience, and there is a continued interest in understanding the biochemical basis for the variation in texture between cattle and their meat cuts in order to improve and minimise variation in tenderness due to production and processing factors. Aims. The present study aimed to investigate the impact of characteristics of meat on Warner-Bratzler shear-force (WBSF) as an indicator of texture of beef as affected by breed type, age/feeding phase, and muscle. Methods. Seventy-five steers of three breed types (Angus, Hereford and Wagyu · Angus) were slaughtered after weaning 6 months old (n = 15), after backgrounding 17 months old (n = 30) and after feedlotting 25 months old (n = 30). At slaughter three muscles (M. supraspinatus, M. semitendinosus and M. longissimus lumborum) were sampled from each steer, and pH, intramuscular fat and collagen content, sarcomere length, and proteolysis (desmin degradation) were measured and used to explain the variation in WBSF after 7 and 14 days of aging. Key results. Meat from Hereford and Angus steers had higher WBSF after 7 days of aging compared with Wagyu · Angus steers, but after 14 days of aging there was only a difference between Hereford and Wagyu · Angus in the M. supraspinatus and M. semitendinosus. The WBSF of the young weaned steers and steers slaughtered after backgrounding were dependent on the degree of proteolysis in the muscles, whereas for steers slaughtered after feedlotting the content of collagen was more important for the WBSF. The amount of intramuscular fat had a significant impact on the differences in WBSF within the specific muscle studied. In contrast to the general dogma that WBSF increase with age, WBSF decreased in M. semitendinosus and M. longissimus lumborum from the weaned 6-month-old steers to the 25-month-old steers finished in feed-lot, whereas in M. supraspinatus the older feed-lot finished steers had a higher WBSF. Conclusion. The factors contributing to the Warner-Bratzler shear force of beef depends on the age/feeding phase of the animal and the muscle and less on the breed type. Implications. Optimisation of texture in beef through breeding and production should address different traits dependent on the age/feeding phase of the slaughter animal.
... The basic experimental details relating to this animal trial have been previously reported [12]. In brief we studied 15 individual 259 day grain fed Angus, Hereford and Wagyu x Angus steers (n = 5 per breed) slaughtered at ~26 months of age as part of the larger experiment detailed by [12]. ...
... The basic experimental details relating to this animal trial have been previously reported [12]. In brief we studied 15 individual 259 day grain fed Angus, Hereford and Wagyu x Angus steers (n = 5 per breed) slaughtered at ~26 months of age as part of the larger experiment detailed by [12]. Management was standardised for all individuals during growth on pasture from weaning through long-feedlotting. ...
... Management was standardised for all individuals during growth on pasture from weaning through long-feedlotting. For the transcriptome analysis of the fat depots we focussed on animals' pasture-fed only during the immediate post-weaning period, rather than animals that received supplement during the immediate post-weaning period [12]. A total of 10 sires were represented across the 15 individuals, with 3 sires per genotype and only 1 or 2 individuals per sire. ...
Background This study used a genome-wide screen of gene expression to better understand the metabolic and functional differences between commercially valuable intramuscular fat (IMF) and commercially wasteful subcutaneous (SC) fat depots in Bos taurus beef cattle.Results We confirmed many findings previously made at the biochemical level and made new discoveries. The fundamental lipogenic machinery, such as ACACA and FASN encoding the rate limiting Acetyl CoA carboxylase and Fatty Acid synthase were expressed at 1.6-1.8 fold lower levels in IMF, consistent with previous findings. The FA elongation pathway including the rate limiting ELOVL6 was also coordinately downregulated in IMF compared to SC as expected. A 2-fold lower expression in IMF of ACSS2 encoding Acetyl Coenzyme A synthetase is consistent with utilisation of less acetate for lipogenesis in IMF compared to SC as previously determined using radioisotope incorporation. Reduced saturation of fat in the SC depot is reflected by 2.4 fold higher expression of the SCD gene encoding the Δ9 desaturase enzyme. Surprisingly, CH25H encoding the cholesterol 25 hydroxylase enzyme was ~36 fold upregulated in IMF compared to SC. Moreover, its expression in whole muscle tissue appears representative of the proportional representation of bovine marbling adipocytes. This suite of observations prompted quantification of a set of oxysterols (oxidised forms of cholesterol) in the plasma of 8 cattle exhibiting varying IMF. Using LC-MS we found the levels of several oxysterols were significantly associated with multiple marbling measurements across the musculature, but (with just one exception) no other carcass phenotypes.Conclusions These data build on our molecular understanding of ruminant fat depot biology and suggest oxysterols represent a promising circulating biomarker for cattle marbling.
... The basic experimental details relating to this animal trial have been previously reported [12]. In brief we studied 15 individual 259 day grain fed Angus, Hereford and Wagyu x Angus steers (n = 5 per breed) slaughtered at ~26 months of age as part of the larger experiment detailed by [12]. ...
... The basic experimental details relating to this animal trial have been previously reported [12]. In brief we studied 15 individual 259 day grain fed Angus, Hereford and Wagyu x Angus steers (n = 5 per breed) slaughtered at ~26 months of age as part of the larger experiment detailed by [12]. Management was standardised for all individuals during growth on pasture from weaning through long-feedlotting. ...
... Management was standardised for all individuals during growth on pasture from weaning through long-feedlotting. For the transcriptome analysis of the fat depots we focussed on animals' pasture-fed only during the immediate post-weaning period, rather than animals that received supplement during the immediate post-weaning period [12]. A total of 10 sires were represented across the 15 individuals, with 3 sires per genotype and only 1 or 2 individuals per sire. ...
Background
This study used a genome-wide screen of gene expression to better understand the metabolic and functional differences between commercially valuable intramuscular fat (IMF) and commercially wasteful subcutaneous (SC) fat depots in Bos taurus beef cattle.
Results
We confirmed many findings previously made at the biochemical level and made new discoveries. The fundamental lipogenic machinery, such as ACACA and FASN encoding the rate limiting Acetyl CoA carboxylase and Fatty Acid synthase were expressed at 1.6-1.8 fold lower levels in IMF, consistent with previous findings. The FA elongation pathway including the rate limiting ELOVL6 was also coordinately downregulated in IMF compared to SC as expected. A 2-fold lower expression in IMF of ACSS2 encoding Acetyl Coenzyme A synthetase is consistent with utilisation of less acetate for lipogenesis in IMF compared to SC as previously determined using radioisotope incorporation. Reduced saturation of fat in the SC depot is reflected by 2.4 fold higher expression of the SCD gene encoding the Δ9 desaturase enzyme. Surprisingly, CH25H encoding the cholesterol 25 hydroxylase enzyme was ~36 fold upregulated in IMF compared to SC. Moreover, its expression in whole muscle tissue appears representative of the proportional representation of bovine marbling adipocytes. This suite of observations prompted quantification of a set of oxysterols (oxidised forms of cholesterol) in the plasma of 8 cattle exhibiting varying IMF. Using LC-MS we found the levels of several oxysterols were significantly associated with multiple marbling measurements across the musculature, but (with just one exception) no other carcass phenotypes.
Conclusions
These data build on our molecular understanding of ruminant fat depot biology and suggest oxysterols represent a promising circulating biomarker for cattle marbling.
... In terms of differential metabolism between depots, previous biochemical evidence points to IMF having relatively slow rates of lipogenesis in both cattle [9] and pigs [10] and under certain nutritional circumstances a substrate preference for glucose carbon over acetate when compared to SC [6,11]. Post-weaning diets tailored to these specific metabolic properties of IMF, such as strategic feeding with high energy concentrate, have had mixed success [12] for reasons not certain but which probably include net energy available for tissue deposition. A recent review emphasises castration, digestion and absorption of feed, glucose availability and vitamin A, D and C levels as important factors in marbling development [13]. ...
... Here, we analyse data from 5 bovine fat depots (IMF, SC, intermuscular, kidney and omental), with a particular focus on the IMF versus SC depot comparison. These functional genomic data are one component of a much larger animal experiment exploring cattle genotype by nutritional effects on fat depot biology [12]. Tissue samples for the present study were taken from 26 month-old steers of 3 genotypes, Angus, Hereford and Wagyu x Angus following high energy nutrition in a feedlot for 259 days. ...
... The basic experimental details relating to this animal trial have been previously reported [12]. In brief we studied 15 individual 259 day grain fed Angus, Hereford and Wagyu x Angus steers (n = 5 per breed) slaughtered at~26 months of age as part of the larger experiment detailed by [12]. ...
Background:
This study used a genome-wide screen of gene expression to better understand the metabolic and functional differences between commercially valuable intramuscular fat (IMF) and commercially wasteful subcutaneous (SC) fat depots in Bos taurus beef cattle.
Results:
We confirmed many findings previously made at the biochemical level and made new discoveries. The fundamental lipogenic machinery, such as ACACA and FASN encoding the rate limiting Acetyl CoA carboxylase and Fatty Acid synthase were expressed at 1.6-1.8 fold lower levels in IMF, consistent with previous findings. The FA elongation pathway including the rate limiting ELOVL6 was also coordinately downregulated in IMF compared to SC as expected. A 2-fold lower expression in IMF of ACSS2 encoding Acetyl Coenzyme A synthetase is consistent with utilisation of less acetate for lipogenesis in IMF compared to SC as previously determined using radioisotope incorporation. Reduced saturation of fat in the SC depot is reflected by 2.4 fold higher expression of the SCD gene encoding the Δ9 desaturase enzyme. Surprisingly, CH25H encoding the cholesterol 25 hydroxylase enzyme was ~ 36 fold upregulated in IMF compared to SC. Moreover, its expression in whole muscle tissue appears representative of the proportional representation of bovine marbling adipocytes. This suite of observations prompted quantification of a set of oxysterols (oxidised forms of cholesterol) in the plasma of 8 cattle exhibiting varying IMF. Using Liquid Chromatography-Mass Spectrometry (LC-MS) we found the levels of several oxysterols were significantly associated with multiple marbling measurements across the musculature, but (with just one exception) no other carcass phenotypes.
Conclusions:
These data build on our molecular understanding of ruminant fat depot biology and suggest oxysterols represent a promising circulating biomarker for cattle marbling.
... Breed and sex differences Intramuscular fat content in the LM varies significantly de pending on the cattle breed. The LM of Wagyu contains the highest fat content (36.5%: average value from two publications [25,26]), and the LM from Korean cattle contains the second highest fat content worldwide (13.7%: average value from four publications [10,2729]), followed by Angus (9.3%: average value from three publications [3032]), Hereford crossbred or Hereford (7.6%: average value from two publications [30,33]), and Brahman (2.8%: average value from four publications [32,3436]) (Table 1). Bos taurus cattle generally have higher marbling and better tenderness than do Bos indicus animals Figure 1. ...
... The genetic potential of individual cattle can significantly affect IMF deposition. Greenwood et al [30] conducted a study to test effects of genotypes and nu trition during the immediate postweaning period on IMF contents in 5 muscles, marbling, and subcutaneous fat (rib fat or P8 rump fat) in Bos Taurus steers. The study was con ducted with steer of three genotypes (Angus, Hereford and Wagyu×Angus): Angus was targeting high IMF and high subcutaneous fat, Hereford was targeting low IMF and high subcutaneous fat, and Wagyu sires Angus dams were target ing high IMF and lower subcutaneous fat. ...
... MS increased with increasing slaughter age from 16.2 months (485 d) to 20.3 months (610 d) in Holstein Friesian and Norwegian dairy breeds [67]. In Angus, Hereford, and Wagyu×Angus, the IMF contents in the 5 muscles (biceps femoris, supraspinatus, semitendinosus, longissimus lumborum, and infraspinatus) and MSA MS increased with the increas ing slaughter stages (0, 168, 326, 431 and 585 d after weaning) [30]. Both MS and IMF contents increased with increasing slaughter age (2, 4, 6, 12, and 24 months) in bulls of German Angus, Galloway, and HolsteinFriesian breeds [24]. ...
Intramuscular fat (IMF) content in skeletal muscle including the longissimus dorsi muscle (LM), also known as marbling fat, is one of the most important factors determining beef quality in several countries including Korea, Japan, Australia and the United States. Genetics and breed, management, and nutrition affect IMF deposition. Japanese Black cattle breed has the highest IMF content in the world, and Korean cattle (also called Hanwoo) the second highest. Here, we review results of research on genetic factors (breed and sex differences and heritability) that affect IMF deposition. Cattle management factors are also important for IMF deposition. Castration of bulls increases IMF deposition in most cattle breeds. The effects of several management factors, including weaning age, castration, slaughter weight and age, and environmental conditions on IMF deposition are also reviewed. Nutritional factors, including fat metabolism, digestion and absorption of feed, glucose/starch availability, and vitamin A, D, and C levels are important for IMF deposition. Manipulating IMF deposition through developmental programming via metabolic imprinting is a recently proposed nutritional method to change potential IMF deposition during the fetal and neonatal periods in rodents and domestic animals. Application of fetal nutritional programming to increase IMF deposition of progeny in later life is reviewed. The coordination of several factors affects IMF deposition. Thus, a combination of several strategies may be needed to manipulate IMF deposition, depending on the consumer's beef preference. In particular, stage-specific feeding programs with concentrate-based diets developed by Japan and Korea are described in this article.
... The deposition of IMF is influenced by many factors such as sex, breed, nutrition, age, and genetics (Rule et al. 1997). Previous studies suggested that the IMF content of buffalo (Di Luccia et al. 2003), Holstein-Friesian ( Albrecht et al. 2006;Kirkland et al. 2007), Norwegian Red ( Kirkland et al. 2007), Galloway (Albrecht et al. 2006), Japanese black steer ( Zembayashi et al. 1995;Okumura et al. 2007Okumura et al. , 2012, crossbred Simmental ( Zhang et al. 2014), Angus, Hereford, and Wagyu × Angus ( Greenwood et al. 2015) increased significantly with age. The peroxisome proliferator-activated receptor gamma-2 (PPARγ2), PPAR gamma coactivator-1 alpha (PGC-1α), and myocyte enhancer factor 2C (MEF2C) are common skeletal muscle genes involved in fat metabolism and muscle development. ...
... We found that the IMF content of Ld, Se, and Sol significantly increased with age. Similar findings have been reported in the muscles from crossbred Simmental ( Zhang et al. 2014), Angus, Hereford, and Wagyu × Angus ( Greenwood et al. 2015). Meat tenderness is one of the most important Fig. 1. ...
PPARγ2, PGC-1α, and MEF2C play an important role in skeletal muscle development and fat deposition. This study aimed to determine their mRNA expression levels in longissimus dorsi (Ld), semitendinosus (Se), and soleus (Sol) muscles of crossbred Simmental bulls and estimate their association with intramuscular fat (IMF) content and meat shear force (MSF). We measured the muscle fiber (MF) density and area, IMF content, and MSF of 6-, 12-, and 36-mo-old bulls. We found that the expression patterns differed with age: the PPARγ2 expression in the three muscles of 36-mo-old bulls was greater than that in the muscles of 6- and 12-mo-old bulls (P < 0.05). Furthermore, PGC-1α expression in Sol of 36-mo-old and MEF2C expression in Ld of 12-mo-old bulls were higher than those in the respective muscles of 6- and 12-mo-old bulls, and 6- and 36-mo-old bulls, respectively (P < 0.05). The MF area, IMF content, and MSF increased with age (P < 0.05). The PPARγ2 mRNA expression in Ld, Se, and Sol was positively correlated with MF area and IMF content (P < 0.05) and negatively correlated with MF density (P < 0.05). Thus, PPARγ2 might be a candidate marker, which is positively correlated with IMF content and MF area.
... Similarly, based on the data from the reduced dataset, no significant effect of age on IMF content (P > 0.05), was identified. In most of the studies conducted in beef cattle breeds, IMF increased with increasing slaughter age (Zembayashi et al., 1995;Albrecht et al., 2006;Greenwood et al., 2015). Sex had a significant effect on IMF (P < 0.001) with highest IMF content in females (0.47), followed by oxen (0.40), and lowest IMF content in bulls (0.16; log-transformed values). ...
The aim of this study was to associate single nucleotide polymorphisms (SNP) of the bovine calcium-activated neutral protease µ-calpain, calpastatin, diacylglycerol-O-acyltransferase, adipose fatty acid binding protein, retinoic acid receptor-related orphan receptor C (RORC), and thyroglobulin (TG) gene with intramuscular fat content (IMF). Therefore, 542 animals of the cattle breed “Rotes Höhenvieh” (RHV) were phenotyped for IMF. Genotyping of the animals was performed using polymerase chain reaction-restriction fragment length polymorphism tests for six SNP from candidate genes for meat quality traits. In addition, we calculated allele substitution and dominance effects on IMF. A subgroup of animals (n = 44, reduced dataset) with extraordinary high IMF was analyzed separately. The mean IMF content was 2.5% (SD: 2.8) but ranged from 0.02% to 23.9%, underlining the breeds’ potential for quality meat production. Allele and genotype frequencies for all SNP were similar in the complete and reduced dataset. Association analyses in the complete dataset revealed the strongest effects of RORC on IMF (P = 0.075). The log-transformed least-squares mean for IMF of genotype g.3290GG was 0.45 ± 0.16, 0.26 ± 0.14 for genotype g.3290GT, and 0.32 ± 0.14 for genotype g.3290TT. In the reduced dataset, we found a significant effect (P < 0.05) of the g.422C>T-SNP of TG on IMF, with highest IMF for genotype CT (0.91 ± 0.17), lowest IMF for genotype TT (0.37 ± 0.25), and medium IMF for genotype CC (0.59 ± 0.16; log-transformed values). Compared to the complete dataset, allele substitution effects increased in the reduced dataset for most of the SNP, possibly due to the selective genotyping strategy, with focus on animals with highest IMF implying strong phenotypic IMF contrast. Dominance effects were small in both datasets, related to the high heritability of IMF. Results indicated RHV breed particularities regarding the effects of meat quality genes on IMF. An explanation might be the breeding history of RHV with focus on adaptation and resilience in harsh outdoor systems. Consequently, it is imperative to develop breed-specific selection strategies. Allele substitution and dominance effects were in a similar direction in both datasets, suggesting the same breeding approaches for different RHV strains in different regions. Nevertheless, a selective genotyping approach (reduced dataset), contributed to more pronounced genotype effect differences on IMF and dominance values.
... However, the outcome is not consistent across all studies. For example, Greenwood et al. (2015) studied Angus, Hereford, and Wagyu  Angus genotypes. They observed a reduction in the depth of subcutaneous rib fat, but no effect on IMF, when they substituted forage grazing with a high-energy concentrate (50% of dietary energy requirements of weaned steers, average body weight of 212 kg) for 168 d, with both dietary groups following the same fattening regime until slaughter at 585 d. ...
In markets for beef and sheep meat, an appropriate level of intramuscular fat (IMF) is highly desirable for meat-eating quality, but strategies to improve it usually lead to an undesirable excess in carcase fat, presenting a major challenge to livestock producers. To solve this problem, we need to understand the partitioning of fat among the major fat depots: IMF, subcutaneous fat (SCF) and visceral fat (VF). In most genotypes of cattle and sheep, the rate of accretion is lower for IMF than for SCF and VF, so genetic selection for a high level of IMF, or the use of an increased dietary energy supply to promote IMF deposition, will increase overall fatness and feed costs. On the other hand, feeding postnatal calves with excessive concentrates promotes IMF deposition, so a nutritional strategy is feasible. With genetic strategies, several problems arise: 1) positive genetic correlations between IMF, SCF and VF differ among genotypes in both cattle and sheep; 2) genotypes appear to have specific, characteristic rates of accretion of IMF during periods of growth and fattening; 3) most breeds of cattle and sheep naturally produce meat with relatively low levels of IMF, but IMF does vary substantially among individuals and breeds so progress is possible through accurate measurement of IMF. Therefore, an essential prerequisite for selection will be knowledge of the genetic correlations and fat accretion rates for each genotype. Currently, selection for IMF is based on existing technology that directly measures IMF in the progeny or siblings, or estimates IMF in live animals. New technology is needed to permit the simultaneous measurement of SCF and IMF in the field, thus opening up the possibility of accurate selection, particularly for fat partitioning in live animals. Specifically, there would be great value in detecting individuals with an IMF advantage at an early age so the generation interval could be shortened and genetic gain accelerated. Genetic gain would also be greatly aided if we could select for genes that control adipogenesis and lipogenesis and are also differentially expressed in the various depots.
... Compared to rangeland and grazing systems, cattle raised on grain or concentrate-mixed rations have higher energy intakes, in the form of acetate, propionate, and butyrate-these being short-chain FAs. These systems may be combined and supplemented grazing cattle with energy-rich feed types to enhance the quality of their diet [131]. These supplements may be cereal grains and meals, by-products of biofuel production, distiller's grain, molasses, and others [7,132,133]. ...
Simple Summary
Nutritional interventions in ruminant livestock management is an essential step to achieving high quality meat and milk products for diversified and competitive global markets. The alterations of fat content, fatty acid profile, and the associated sensory properties of meat and milk have attracted much attention; they are accomplished with the managing of feeding systems and nutrition of ruminant diets. The literature has detailed various feed types and ingredients that facilitate the sustainable use of abundant, novel by-products, secondary products, non-conventional feedstuffs, or minimally processed biological materials within ruminant farming systems. Relevant to major feed ingredients is the knowledge of their macro- and micronutrients, as well as their bioactivity and functionality in meat and milk products. This review examines these and provides an overview of various concentrate feeds and forages that are fed to ruminants, and how they relate to the fat content and fatty acid profile of their meat and milk products. These insights will be valuable to those seeking to understand and adopt nutritional measures for the enhancement of domesticate ruminant meat and milk products.
Abstract
The meat and milk products from domesticated ruminants are important foods within a balanced diet, offering a rich source of energy, protein, fats, minerals, and vitamins. The sensorial properties of meat and milk are mainly linked to their fat content and fatty acid composition, which are influenced by the feeding background or nutrient composition of diets. While several studies have investigated the nutritional effects on the fat content and fatty acid profile of ruminant meat and milk, as well as their relationship with sensorial properties, a comprehensive overview of these effects is lacking. This paper summarises current literature and discusses changes to fatty acid composition (including ω-3 concentrations), fattiness, and associated quality traits of sheep, goat, beef cattle, alpaca, and llama meat that can be achieved by using different forages or feeds in a total mixed ration. Additionally, it presents the shelf life and nutritional value of meat, milk, and cheeses from the milk of dairy cattle, buffalo, goats, and sheep as influenced by a ruminant diet. Further advancement in these areas will promote the sustainability of ruminant production and its associated feeding systems in achieving premium quality animal-derived foods.
... The IMF content in LM of Japanese Black steers cloned from somatic cells increased with the slaughter age too: 23.7% at 20 months, 38.7% at 25 months, and 41.1% at 30 months of age [92]. The IMF contents and marbling scores of five different muscle groups (biceps femoris, supraspinatus, semitendinosus, longissimus lumborum, and infraspinatus) in three common beef cattle breeds (Angus, Hereford, and Wagyu × Angus) increased with the slaughter age [93]. ...
Intramuscular fat, also referred to as marbling fat, is the white fat deposited within skeletal muscle tissue. The content of intramuscular fat in the skeletal muscle, particularly the longissimus dorsi muscle, of cattle is a critical determinant of beef quality and value. In this review, we summarize the process of intramuscular fat development and growth, the factors that affect this process, and the molecular and epigenetic mechanisms that mediate this process in cattle. Compared to other species, cattle have a remarkable ability to accumulate intramuscular fat, partly attributed to the abundance of sources of fatty acids for synthesizing triglycerides. Compared to other adipose depots such as subcutaneous fat, intramuscular fat develops later and grows more slowly. The commitment and differentiation of adipose precursor cells into adipocytes as well as the maturation of adipocytes are crucial steps in intramuscular fat development and growth in cattle. Each of these steps is controlled by various factors, underscoring the complexity of the regulatory network governing adipogenesis in the skeletal muscle. These factors include genetics, epigenetics, nutrition (including maternal nutrition), rumen microbiome, vitamins, hormones, weaning age, slaughter age, slaughter weight, and stress. Many of these factors seem to affect intramuscular fat deposition through the transcriptional or epigenetic regulation of genes directly involved in the development and growth of intramuscular fat. A better understanding of the molecular and cellular mechanisms by which intramuscular fat develops and grows in cattle will help us develop more effective strategies to optimize intramuscular fat deposition in cattle, thereby maximizing the quality and value of beef meat.
... Wagyu cattle are known for their ability to deposit excessive amounts of intramuscular fat within the longissimus muscle. The longissimus muscle from finished Wagyu cattle typically contains greater than 30% crude fat compared to 5-15% crude fat in the longissimus muscle of finished bos taurus breeds of cattle [1][2][3][4]. Greater intramuscular fat content has a positive impact on overall eating quality for consumers [5]. Furthermore, the fatty acid composition of the intramuscular fat from Wagyu cattle contains a greater proportion of oleic acid (C18:1cis9: 40-50%) compared to bos taurus breeds (C18:1cis9: 30-40%) fed to different endpoint body weights [6]. ...
Wagyu cattle are well known for their greater intramuscular fat content which improves eating quality for consumers. These experiments were designed to investigate the impact of olive cake supplementation on Wagyu steer growth performance, longissimus muscle fatty acid composition, and in vitro rumen fermentation characteristics. We hypothesized that feeding with olive cake would improve animal performance and increase oleic acid (C18:1cis9) composition in the longissimus muscle. Experiment 1: Eighty-three American Wagyu steers (725 ± 10.7 kg) were used in this experiment. Steers were blocked by initial body weight (BW) and randomly assigned within blocks to one of two treatments. Treatments consisted of (1) control (basal ration with no olive cake) or (2) control diet + 5% supplemental olive. Steers were housed in feedlot pens (n = 4 steers/pen; 11 replicates/treatment) and fed a finishing diet typical for Wagyu cattle. Steers were individually weighed every 28 d throughout the 177 d experiment. Longissimus muscle samples were obtained for fatty acid analysis at the time of slaughter. Experiment 2: Rumen fluid from three beef steers (480 ± 10 kg) fitted with rumen canulae was used to investigate the impact of olive cake on in vitro rumen fermentation characteristics. Treatments consisted of (1) control (no olive cake) or (2) 5% olive cake. Results: Experiment 1: Steers receiving olive cake had a lower (p < 0.05) final BW and DM intake when compared to steers receiving the control diet. Longissimus muscle C18:2 and C22:6 n-3 were greater (p < 0.05) and C18:1cis9 tended (p < 0.06) to be greater in steers receiving olive cake when compared to controls. Experiment 2: Dry matter, acid detergent fiber, and neutral detergent fiber disappearance and molar proportions of short chain fatty acids were similar across treatments. The weight percentage of C14:1 was greater in in vitro rumen fluid fermented with olive cake when compared to controls. All other long chain fatty acids were similar across treatments. Under the conditions of this experiment, feeding olive cake at 5% of the diet DM reduced live animal performance and had minimal impacts on longissimus muscle fatty acid composition and in vitro rumen fermentation characteristics.
... 一般来说, 经过选育的肉用型 品种脂肪沉积能力低于未经选育的地方品种或经选育 的生产"雪花肉"的专门品种 [41] . 普通牛(Bos taurus)比 瘤牛(Bos indicus)的沉积肌内脂肪的能力强 [17,40,42,43] , 如海福特牛(Hereford)(8.3%) [44] 以及安格斯牛(Angus) ...
... Park et al. [69], on the basis of papers written by Albrecht et al. [74] and Irie et al. [75], determined that the average IMF content in the longissimus dorsi (LD) muscle in the Japanese Wagyu breed was 36.5%; for the Korean Hanwoo breed, it was 13.7% [76][77][78][79], while for the Angus breed, it was 7.1% [80][81][82]. For the Hereford crossbreed, the figure was 6.9%. ...
The single-nucleotide polymorphism (SNP) form of genes is a valuable source of information regarding their suitability for use as specific markers of desirable traits in beef cattle breeding. For several decades, breeding work focused on improving production efficiency through optimizing the feed conversion ratio and improving daily gains and meat quality. Many research teams previously undertook research work on single-nucleotide polymorphism in myostatin (MSTN), thyroglobulin (TG), calpain (CAPN), and calpastatin (CAST) proteins. The literature review focuses on the most frequently addressed issues concerning these genes in beef cattle production and points to a number of relevant studies on the genes’ polymorphic forms. The four genes presented are worth considering during breeding work as a set of genes that can positively influence productivity and production quality.
... Generally, Bos taurus types present higher marbling than Bos indicus breeds [65]. Examples include Brahman feedlot-fed steers, with an IMF content of 3.1%, in comparison to Bos taurus breeds, such as Angus (6.2%) [66,67] and Hereford (8.3%; fed forage with or without supplementation of high energy diet) [68], at similar ages and in the same muscle. Regardless of the divergence between taurus and indicus, Asian cattle breeds are known for their high IMF content [64]; Wagyu (Japanese Black cattle) and Hanwoo (Korean) feedlot steers had an IMF content of 34.3% and 13.3%, respectively, in their longissimus thorasis muscle [69,70]. ...
Global animal production systems are often criticized for their lack of sustainability and insufficient resilience to ensure food security. The ‘farm-to-fork’ approach aims at orienting food systems towards the creation of a positive environmental impact, nutritious, healthy, safe and sufficient foods, and fairer economic returns for primary producers. Many countries rely on an imported supply of live animals to fulfill their needs for fresh meat. In Israel, ~60% of the sources of fresh beef come from the import of live animals. In order to encourage sustainable beef production in Israel, the proportion of local beef should be raised at the expense of imported animals. However, for this to be achieved, the superior performance of local beef should be justified. The current study was conducted to compare between the meat quality characteristics of local (Israeli Holstein; N = 205) vs. imported (Australian; N = 169) animals. Generally, while the imported calves presented a higher dressing percentage (p < 0.0001), the local animals were characterized by tenderer meat (p < 0.0001), longer sarcomeres (p < 0.0001), higher a* color attributes and pH (p < 0.001), superior cooking (p = 0.002) and thawing loss (p < 0.0001), higher intra-muscular fat (IMF) content, and a higher PUFA proportion (p < 0.01 and p < 0.0001, respectively) and PUFA:SFA ratio. The findings shown herein may provide sound arguments for stakeholders and policy makers to facilitate sustainable local beef production in Israel.
... The increased days of age in the traditionally weaned group as well as calves fed for 90 days could also account for the increased HCW. A serial slaughter study shows that increased days of age resulted in increased HCW [27]. ...
The objective of this study was to determine how weaning age, days on supplements, and lipid supplementation affected the growth and marbling deposition of steers. Steers from a single sire were early weaned (n = 24) at 150 ± 11 days of age or traditionally weaned (n = 24) at 210 ± 11 days of age. Steers were assigned to control (n = 12/weaning group) or an isocaloric, isonitrogenous rumen by-pass lipid (RBL, n = 12/weaning group) for either 45 (n = 6/treatment) or 90 (n=6/treatment) days then harvested. Steer body weight (BW) was recorded on days −14 and −7, then BW and blood samples were collected on days 0, 22, 45, 66, and 90. The right rib section of each animal was collected for proximate analysis. Longissimus dorsi from RBL steers had increased lipids compared with control steers (3.6 ± 0.2 vs. 2.4 ± 0.2% on a wet basis; p < 0.0001). Steers fed for 90 days had greater (p = 0.02) concentrations of Longissimus dorsi lipid (3.3 ± 0.2%) than those fed for 45 days (2.7 ± 0.2%). There was a weaning age by treatment by days on feed interaction for intramuscular adipocyte diameter (p = 0.02) in which early weaned RBL fed for 90 days steers had an increased adipocyte diameter compared to the early weaned control fed for 90 and early weaned fed for 45 days steers with all other treatment groups as intermediates. Supplementation of RBL increased concentrations of C18:2, C20:4, and total fatty acids on days 45 and 90 (p ≤ 0.05). Data show that RBL supplementation increased the marbling content of the Longissimus dorsi. Furthermore, a longer period of supplementation resulted in increased adipose diameter.
... This is despite a reduction in subcutaneous fat depth because of selection. There is likely to be systematic variation in the proportion of FleshFM in the IMF (kg) pool in different breeds (Greenwood et al., 2015), but to accurately represent this on a breed level clearly requires more data. Marble score is derived directly from ChemIMF % using a non-linear model (equation (15)) with an AdjR 2 of 0.60. ...
Until recently, beef carcass payment grids were predominantly based on weight and fatness categories with some adjustment for age, defined as number of adult teeth, to determine the price received by Australian beef producers for slaughter cattle. With the introduction of the Meat Standards Australia ( MSA ) grading system, the beef industry has moved towards payments that account for intramuscular fat ( IMF ) content (marble score ( MarbSc )) and MSA grades. The possibility of a payment system based on lean meat yield ( LMY , %) has also been raised. The BeefSpecs suite of tools has been developed to assist producers to meet current market specifications, specifically P8-rump fat and hot standard carcass weight ( HCW ). A series of equations have now been developed to partition empty body fat and fat-free weight into carcass fat-free mass ( FFM ) and fat mass ( FM ) and then into flesh FFM ( FleshFFM ) and flesh FM ( FleshFM ) to predict carcass components from live cattle assessments. These components then predict denuded lean (kg) and finally LMY (%) that contribute to emerging market specifications. The equations, along with the MarbSc equation, are described and then evaluated using two independent datasets. The decomposition of evaluation datasets demonstrates that error in prediction of HCW (kg), bone weight (BoneWt, kg), FleshFFM (kg), FleshFM (kg), MarbSc and chemical IMF percentage ( ChemIMF% ) is shown to be largely random error (%) in evaluation dataset 1, though error for ChemIMF% was primarily slope bias (%) in evaluation dataset 1, and BoneWt had substantial mean bias (%) in evaluation dataset 2. High modelling efficiencies of 0.97 and 0.95 for predicting HCW for evaluation datasets 1 and 2, respectively, suggest a high level of accuracy and precision in the prediction of HCW. The new outputs of the model are then described as to their role in estimating MSA index scores. The modelling system to partition chemical components of the empty body into carcass components is not dependent on the base modelling system used to derive empty body FFM and FM. This can be considered a general process that could be used with any appropriate model of body composition.
... This is generally consistent with our results in calves of differing genotypes for fat distribution weaned at a more conventional age (6-8 months) and weight (average 223 kg). These calves were fed pasture-only or pasture plus a high energy grain-based supplement at levels resulting in equivalent growth rates for 168 days from weaning (Greenwood et al. 2015). However, at about 600 days of age following 256 days of lot feeding, carcass rib and rump fat depths and marbling scores were reduced in the steers supplemented with high energy grain-based pellets post-weaning, but effects on intramuscular fat percentage were modest and variable between muscles differing in capacity for marbling. ...
... Steer genotypes, nutritional systems and slaughter stages are described in detail by Greenwood et al. (2015). In brief, serial slaughters were undertaken at 5 stages of growth on Angus (A), Hereford (H) and Wagyu x Angus (WxA) steers (n=55 per breed) targeted to differ in fat depot distribution: A, targeting high IMF and high SCF; H, targeting low IMF and high SCF; and WxA, targeting high IMF and lower SCF. ...
... These research may result in more feasible and efficient approaches to simultaneously promote the development of intramuscular adipose tissue and inhibit the formation of intramuscular connective tissue. Moreover, significant variations in the tenderness and marbling between different cattle breeds under the same developmental conditions have been noticed (Xie et al., 1996;Kuehn et al., 2010;Albrecht et al., 2011;Walmsley et al., 2015), which might be due to some differences in the differentiation potential of FAPs from cattle of different breeds. Although these differences may be ultimately caused by some variation at the genetic level, the identification and validation of a mutation or a polymorphism are usually very challenging, especially when the mutation or polymorphism is located in the noncoding sequence of a gene. ...
The intramuscular adipose tissue deposition in the skeletal muscle of beef cattle is a highly desired trait essential for high-quality beef. In contrast, the excessive accumulation of crosslinked collagen in intramuscular connective tissue contributes to beef toughness. Recent studies revealed that adipose tissue and connective tissue share an embryonic origin in mice and may be derived from a common immediate bipotent precursor in mice and humans. Having the same linkages in the development of adipose tissue and connective tissue in beef, the lineage commitment and differentiation of progenitor cells giving rise to these tissues may directly affect beef quality. It has been shown that these processes are regulated by some key transcription regulators and are subjective to epigenetic modifications such as DNA methylation, histone modifications, and microRNAs. Continued exploration of relevant regulatory pathways is very important for the identification of mechanisms influencing meat quality and the development of proper management strategies for beef quality improvement.
... Duckett et al. (2007) found that higher stocker growth rate increased intramuscular lipid deposition in steers finished on concentrates. In contrast, supplementation of corn (< 1% of body weight) on pasture (Pavan and Duckett, 2008;Greenwood et al., 2015;Wright et al., 2015) does not appear to alter marbling deposition. Smith and Crouse (1984) found that glucose provided the majority of acetyl units for intramuscular fat deposition; whereas acetate provided the majority of acetyl units for subcutaneous adipose deposition. ...
Forty Angus-cross steers (280 ± 21.4 kg BW, 8 mo.) were used to examine the effects of exposure to 2 diets [high concentrate diets (CONC) versus high quality forages (FOR)] during 2 time periods [early (EARLY; at 30-d post weaning) or late (LATE; just prior to slaughter)] on animal growth, marbling deposition and tenderness. Steers were blocked by weight and randomly assigned to four dietary treatments: 1) CONC-FOR, 2) CONC-CONC, 3) FOR-CONC, or 4) FOR-FOR. Exposure to CONC during the EARLY or LATE period increased (P < 0.05) growth and fat deposition compared to FOR-FOR. Hot carcass weight was greater (P < 0.05) for CONC-CONC and FOR-CONC steers than FOR-FOR and CONC-FOR due to changes in dressing percent. Marbling score was greater (P < 0.05) for CONC-CONC and CONC-FOR compared to FOR-FOR. Exposure to CONC during the EARLY period (CONC-FOR and CONC-CONC) increased (P < 0.05) n-6 polyunsaturated fatty acids (PUFA) deposition in longissimus muscle (LM) and subcutaneous adipose tissue (SQ); whereas, exposure to CONC during the LATE period (CONC-CONC and FOR-CONC) reduced (P < 0.05) n-3 PUFA, trans-11 octadecenoic acid and cis-9 trans-11 isomer of conjugated linoleic acid (CLA). Warner-Bratzler shear force at d 2 and 7 of postmortem aging in ribeye steaks from CONC-CONC and FOR-CONC was greater (P < 0.05) than FOR-FOR and CONC-FOR. Lipogenic gene expression was upregulated (P < 0.05) and lipolytic gene expression was downregulated (P < 0.06) in SQ from CONC-CONC and FOR-CONC compared to FOR-FOR. Overall, exposure to CONC in both periods increased growth rate and marbling deposition but LATE exposure had the greatest impact on adipose lipogenesis and lipolysis, fatty acid composition, and tenderness
... Duckett et al. (2007) found that higher stocker growth rate increased intramuscular lipid deposition in steers finished on concentrates. In contrast, supplementation of corn (< 1% of body weight) on pasture (Pavan and Duckett, 2008;Greenwood et al., 2015;Wright et al., 2015) does not appear to alter marbling deposition. Smith and Crouse (1984) found that glucose provided the majority of acetyl units for intramuscular fat deposition; whereas acetate provided the majority of acetyl units for subcutaneous adipose deposition. ...
Forty Angus-cross steers (280 ± 21.4 kg BW, 8 mo.) were used to examine the effects of exposure to 2 diets [high concentrate diets (CONC) versus high quality forages (FOR)] during 2 time periods [early (EARLY; at 30-d post weaning) or late (LATE; just prior to slaughter)] on animal growth, marbling deposition and tenderness. Steers were blocked by weight and randomly assigned to four dietary treatments: 1) CONC-FOR, 2) CONC-CONC, 3) FOR-CONC, or 4) FOR-FOR. Exposure to CONC during the EARLY or LATE period increased (P < 0.05) growth and fat deposition compared to FOR-FOR. Hot carcass weight was greater (P < 0.05) for CONC-CONC and FOR-CONC steers than FOR-FOR and CONC-FOR due to changes in dressing percent. Marbling score was greater (P < 0.05) for CONC-CONC and CONC-FOR compared to FOR-FOR. Exposure to CONC during the EARLY period (CONC-FOR and CONC-CONC) increased (P < 0.05) n-6 polyunsaturated fatty acids (PUFA) deposition in longissimus muscle (LM) and subcutaneous adipose tissue (SQ); whereas, exposure to CONC during the LATE period (CONC-CONC and FOR-CONC) reduced (P < 0.05) n-3 PUFA, trans-11 octadecenoic acid and cis-9 trans-11 isomer of conjugated linoleic acid (CLA). Warner-Bratzler shear force at d 2 and 7 of postmortem aging in ribeye steaks from CONC-CONC and FOR-CONC was greater (P < 0.05) than FOR-FOR and CONC-FOR. Lipogenic gene expression was up-regulated (P < 0.05) and lipolytic gene expression was downregulated (P < 0.06) in SQ from CONC-CONC and FOR-CONC compared to FOR-FOR. Overall, exposure to CONC in both periods increased growth rate and marbling deposition but LATE exposure had the greatest impact on adipose lipogenesis and lipolysis, fatty acid composition, and tenderness.
... Previous studies also noted that BFT was low in not only Hanwoo, but also Wagyu steers compared to the Angus breed [13]. A prior study indicated that Angus BFT is consistently higher than Wagyu under similar diet conditions [13,14]. ...
Hanwoo cattle are an important food source in Korea and their supply can have a major impact on meat availability for Korean consumers. The Hanwoo population was 1.8 million head in 2005 and gradually increased to 2.6 million in 2015. Per capita beef consumption has also increased, to 11.6 kg per year in 2015, and is expected to continue to increase. Because intramuscular fat (IMF) percentage is a critical contributor to meat quality, Hanwoo cattle are fed a high-energy corn-based diet for long fattening periods. Long fed diet causes significant alterations in fat percentage in the loin muscle and other areas of the carcass. However, these long feeding periods increase feeding costs and beef prices. Recently, there has been increased Korean consumer demand for lean beef which has less fat, but is tender and priced more reasonably. These consumer demands on the Korean beef industry are driving differing beef production systems and also changes to the beef grading methodology. Korean government has made a significant investment to select bulls with favorable production traits using progeny testing. Progeny tested bull semen has been disseminated to all Hanwoo farmers. Beef traceability system in Korea was employed for all cattle breeds since 2009. Hanwoo cattle are ear-marked with a 12-digit identification number from birth to slaughter. This number allows traceability of the management history of individual cattle, and also provides information to consumers. Traceability including management information such as herd, farm, year of birth, and carcass data determine estimated breeding values of Hanwoo. For a sustainable Hanwoo industry, research scientists in Korea have attempted to develop feeds for efficient fattening periods and precision feeding systems based on genetic information for Hanwoo cattle. These initiatives aim to Korean consumer demands for beef and provide more precision management in beef production in Korea.
... Four diets were used to evaluate the sensitivity of the parameters associated with the CH 4 -related outputs as mentioned above: (i) a barley-based feedlot diet representative of Australian systems (AU; Greenwood et al. 2015), (ii) a maize-based feedlot diet representative of northern California systems (US; unpublished data from UC Davis beef feedlot), (iii) a New Zealand mature ryegrass pasture diet (NZ; Jonker et al. 2016) and (iv) a Canadian bromegrass-based pasture diet (CN; Boadi et al. 2002). The feed compositions are reported in Table 1. ...
The present study evaluated the behaviour of the AusBeef model for beef production as part of a 2 × 2 study simulating performance on forage-based and concentrate-based diets from Oceania and North America for four methane (CH 4 )-relevant outputs of interest. Three sensitivity analysis methods, one local and two global, were conducted. Different patterns of sensitivity were observed between forage-based and concentrate-based diets, but patterns were consistent within diet types. For the local analysis, 36, 196, 47 and 8 out of 305 model parameters had normalized sensitivities of 0, >0, >0·01 and >0·1 across all diets and outputs, respectively. No parameters had a normalized local sensitivity >1 across all diets and outputs. However, daily CH 4 production had the greatest number of parameters with normalized local sensitivities >1 for each individual diet. Parameters that were highly sensitive for global and local analyses across the range of diets and outputs examined included terms involved in microbial growth, volatile fatty acid (VFA) yields, maximum absorption rates and their inhibition due to pH effects and particle exit rates. Global sensitivity analysis I showed the high sensitivity of forage-based diets to lipid entering the rumen, which may be a result of the use of a feedlot-optimized model to represent high-forage diets and warrants further investigation. Global sensitivity analysis II showed that when all parameter values were simultaneously varied within ±10% of initial value, >96% of output values were within ±20% of the baseline, which decreased to >50% when parameter value boundaries were expanded to ±25% of their original values, giving a range for robustness of model outputs with regards to potential different ‘true’ parameter values. There were output-specific differences in sensitivity, where outputs that had greater maximum local sensitivities displayed greater degrees of non-linear interaction in global sensitivity analysis I and less variance in output values for global sensitivity analysis II. For outputs with less interaction, such as the acetate : propionate ratio and microbial protein production, the single most sensitive term in global sensitivity analysis I contributed more to the overall total-order sensitivity than for outputs with more interaction, with an average of 49, 33, 15 and 14% of total-order sensitivity for microbial protein production, acetate : propionate ratio, CH 4 production and energy from absorbed VFAs, respectively. Future studies should include data collection for highly sensitive parameters reported in the present study to improve overall model accuracy.
This study investigates the effects of varying energy levels in diets on Black Angus steers, focusing on growth performance, muscle composition, rumen microbial community, and their interrelationships. Twenty-seven Black Angus steers, aged approximately 22 months and weighing 520 ± 40 kilograms, were randomly divided into three groups: low-energy (LE), medium-energy (ME), and high-energy (HE). Each group consisted of nine individuals. The steers were fed diets with energy levels of 6.657 MJ/kg (LE), 7.323 MJ/kg (ME), and 7.990 MJ/kg (HE) following a 14-day pre-feeding period, with a subsequent 90-day main experimental phase. After the 90-day feeding period, both the HE and ME groups exhibited significantly higher average daily weight gain (ADG) compared to the LE group (p < 0.05). The feed-to-weight ratios were lower in the HE and ME groups compared to the LE group (p < 0.05). The HE group showed significantly higher crude fat content in the longissimus dorsi muscle compared to the LE group (p < 0.05), with total fatty acid content in the muscle surpassing that in the ME and LE groups (p < 0.05). As dietary energy levels increased, the diversity of the rumen microbial community decreased (p < 0.05), and significant differences in bacterial community structure were observed between the LE and HE groups (p < 0.05). The results suggest that higher dietary energy levels enhance growth performance and alter muscle composition in Black Angus steers, while also influencing the rumen microbial community. This study contributes to understanding optimal dietary strategies for finishing Angus cattle to improve beef quality, economic returns, and the development of standardized production procedures.
Meat quality measures, including objective measures of tenderness (shear force and compression), were taken on 2 muscles [M. longissimus thoracis et lumborum (LTL) and M. semitendinosus (ST)] from 7566 carcasses from temperate (TEMP) and tropically adapted (TROP) beef cattle breeds. Animals were finished to 1 of 3 market carcass weight end-points (220, 280, or 340 kg) either on pasture or in a feedlot, and in 2 different geographic regions for TROP. Both the phenotypic and genetic expression of the traits were estimated at each market weight and for each finishing regime. Heritabilities and correlations between the traits were estimated for TEMP and TROP separately. Smaller additive variances and heritabilities were observed for temperate breeds compared with tropically adapted breeds for most of the traits studied. For TROP, the heritability of traits measured on the ST muscle [compression (ST_C), shear force (ST_SF), and L* Minolta lightness value (ST_L*)] was 0.27, 0.42, and 0.16, respectively, and for traits measured on the LTL muscle [compression (LTL_C), shear force (LTL_SF), L* Minolta lightness value (LTL_L*), a* Minolta redness value (LTL_a*), cooking loss% (LTL_CL%), and consumer assessed tenderness score (LTL_TEND)] 0.19, 0.30, 0.18, 0.13, 0.20, and 0.31, respectively. For TEMP, the heritability of traits measured on the ST muscle [ST_C, ST_SF, ST_L*, a* Minolta redness value (ST_a*), cooking loss % (ST_CL%)] was 0.12, 0.11, 0.17, 0.13, and 0.15, respectively, and of traits measured on the LTL muscle (LTL_C, LTL_SF, LTL_L, and LTL_TEND) were 0.08, 0.09, 0.17 and 0.18 respectively. Genetic correlations were moderate to high for tenderness measures (shear force and compression) between muscles for the same tenderness measure (e.g. LTL_SF and ST_SF was 0.46 for TROP) and within a muscle for the different measures (e.g. ST_C and ST_SF was 0.83 for TROP). Phenotypic and genetic correlations between LTL_L* and all objective measures of tenderness were negative (e.g. LTL_SF and LTL_L* for TROP was –0.40). The genetic relationship between LTL_SF and LTL_TEND was –0.79 and –0.49 for TROP and TEMP, respectively. Finishing system affected the phenotypic expression of all traits. Pasture-finished, compared with feedlot-finished, animals had higher shear force and compression measures, darker meat colour, and lower sensory tenderness scores for both TEMP and TROP. For TROP, heifers had higher shear force and compression measures, lower sensory tenderness scores, and darker meat colour (lower L* values) than steers. Genetic correlations between markets were generally high and close to unity with the exception of the ST_L*, LTL_L*, ST_C, and ST_SF for TEMP. Geographic region had little effect on the phenotypic and genetic expression of meat quality traits for TROP. Genetic correlations between finishing regimes for all traits were positive and close to unity, with the exception of ST_C and LTL_SF for TEMP, and LTL_L* and LTL_CL% for TROP. Genetic improvement of meat quality traits is a possibility for tropically adapted breeds given the moderate heritabilities, adequate phenotypic variance, generally favourable genetic correlations between traits, and little evidence of genotype by environment interactions.
The effects of prior growth on subsequent growth and body composition of cattle potentially affect the profitability of growing cattle to meet specifications based on weight and fatness. The effects of different growth rates and patterns of growth between weaning (about 230 kg) and entry to finishing (average 400 kg) on growth rate, carcass characteristics and intramuscular fat content of steers finished on pasture and in a feedlot on a predominantly grain ration to 2 liveweights (520 kg, Korean and >600 kg, Japanese) are reported here. Over a period of 4 years (1994–1997), 1095 Bos taurus steers of 4 breeds (Angus, Hereford, Murray Grey and Shorthorn), were allocated to 1 of 3 grow-out pathways from weaning until entry into finishing. The pathways were based on introduced pasture (P1), with different animal growth rates induced by strategic supplementation with a pelleted concentrate feed (P2), or a forage crop (P3) (Ayres et al. 2001; Dicker et al. 2001).
In general, the mean growth rate of steers from the different growth pathways during finishing was inversely related to mean growth rate during grow-out. However, where the difference in liveweight at the end of grow-out was greater than 15 kg, increased growth rate during finishing was insufficient to permit complete catch up of liveweight by the end of finishing. There was no further compensation beyond 520 kg liveweight. Steers with better nutrition during grow-out tended to have more intramuscular fat at Japanese market weights, but lower retail meat yield. Steers finished on pasture had less fat thickness and intramuscular fat content than those finished on the grain based ration. Compared with P3 steers, there was a tendency for steers from pathways P1 and P2 to have lower intramuscular fat content in their M. longissimus at Japanesese market weights.
The objectives of this study were to assess the effects of early grain feeding on acetate and glucose turnover rates and acetate and glucose preference for palmitate synthesis by subcutaneous fat (SCF), intramuscular fat (IMF), and visceral fat (VF) in finishing steers. Sixteen Angus × Simmental steers were used in the study; 8 were early weaned (EW) and fed a high-grain diet immediately after weaning for 100 or 148 d, and 8 remained with their dams on pasture until weaning at 202 ± 5 or 253 ± 5 d of age. Normal weaned (NW) and EW animals were combined and grazed to 374 ± 5 or 393 ± 5 d of age, when they were placed on a corn silage-based finishing ration until they achieved a SCF thickness of 1.0 to 1.2 cm (494 ± 17 d of age for EW steers and 502 ± 12 d of age for NW steers). Immediately before harvest, steers were continuously infused for 12 h with [H] acetate (1.63 mmol/min; = 8) or [U-C] glucose (0.07 mmol/min; = 8). Blood samples were collected before initiation of infusions and at the end of the infusion from 8 animals or at 1-h intervals for the first 11 h and at 15-min intervals for the last hour of infusion for the other 8 animals. Adipose tissue samples from SCF, IMF, and VF depots were collected at harvest, and lipids were extracted. Plasma enrichments of acetate and glucose and palmitate enrichment in each depot were used to calculate plasma turnover rates and fractional synthesis rates (FSR; % per h) of palmitate from each isotope. Early weaned steers had greater marbling scores compared to NW steers ( < 0.05). Plasma turnover rates and FSR for EW and NW steers were similar except for SCF, where a greater FSR from acetate was observed for EW steers. It is possible the greater FSR for SCF was due to harvesting the animals at a slightly more advanced stage of conditioning as evidenced by the trend for greater 12th rib fat ( = 0.07). Plasma acetate turnover and palmitate FSR from acetate were much greater ( < 0.05) than the corresponding rates from glucose, supporting the primary role of acetate as an energy source and the primary substrate for lipid synthesis across fat depots. However, FSR from acetate and glucose were not different among depots, suggesting that any potential effects of dietary starch on differential deposition of energy in SCF and IMF are not substrate driven.
Early weaning of calves to a high concentrate diet results in greater fat deposition and suggests early postnatal metabolic imprinting events may be exploited as a management tool to improve cattle value. Our objective was to implement a short, high energy dietary intervention prior to a typical grazing period to manipulate intramuscular fat deposition in finishing cattle. Fall-born Angus-sired steer calves (n = 24) were stratified by sire and randomly assigned to normal weaned (NW) or metabolic imprinted (MI) treatments. At 105 ± 6d (135kg), MI calves were transitioned to a diet containing 20% CP and 1.26 Mcal/kg NEg. Metabolic imprinted calves were fed ad libitum as a group. Normal weaned calves remained on their dam until 253 ± 6 d of age. At this time, treatment groups were combined and grazed for 156 d on a mixed summer pasture. Following the grazing phase, steers were adapted to a corn silage-based feedlot diet and performance was monitored on 28-d intervals. Calves were staged for harvest based on back fat endpoint (target 1.0-1.2 cm). Metabolic imprinted calves were heavier (P < 0.05) than NW calves (341 vs. 265 ± 4.2 kg) at normal weaning age. During the grazing phase, NW steers gained more weight than (P < 0.05) MI steers (0.69 vs. 0.35 ± 0.03 kg/d). Feedlot performance and USDA yield grade were similar (P > 0.20) between treatments. However, MI steers produced heavier (P < 0.05) carcasses (564 vs. 524 ± 5.6 kg) with higher (P < 0.001) marbling scores (645 vs. 517 ± 23). Therefore, calves consuming a high concentrate diet for 148 d after early weaning produced higher quality carcasses. This suggests early weaning and feeding a high concentrate prior to grazing is a viable strategy to increase marbling deposition compared to a traditional production system.
This study aimed to examine the impact of early weaning on residual feed intake, and other production and carcass traits, in a group of cattle subjected to early or conventional weaning treatments, but otherwise managed as contemporaries. Shorthorn (n = 140) calves were randomly allocated by sex and sire to early and conventional weaning treatments. Early weaned animals (n = 69) were weaned at an average of 123 days of age and 145 kg liveweight, while conventionally weaned steers and heifers (n = 71) were 259 days old at weaning and 273 kg. Following conventional weaning, animals were managed as contemporaries through backgrounding, and entered feedlot finishing at a mean age of 353 and 408 days for heifers and steers, respectively, for finishing and feed intake testing. At the conclusion of feed intake testing hip height was measured, and animals were ultrasound scanned to assess fat depth, eye muscle area and percent intramuscular fat. Early weaned animals were significantly lighter (P < 0.001) than their conventionally weaned contemporaries, when weighed at conventional weaning. The weight difference observed at conventional weaning of 19.4 kg between treatment groups persisted throughout the experiment, with significant (P < 0.05) differences of 17.1, 15.6 and 15.8 kg at feedlot entry, and the start and end of the feed intake test period, respectively. Weaning treatment also approached significance for daily feed intake (P = 0.06), with early weaned animals tending to eat less than their conventionally weaned contemporaries (daily feed intake = 11.6 and 12.0 kg, respectively). Weaning treat\ment did not significantly affect feed efficiency whether measured as residual feed intake (P = 0.64) or feed conversion ratio (P = 0.27). None of the other traits measured were significantly affected by weaning treatment. These data showed that early weaning, as implemented for this experiment, resulted in animals that were lighter than their conventionally weaned contemporaries through backgrounding and finishing. Weaning treatment did not, however, influence feed efficiency or the post-weaning growth and carcass composition traits measured for this experiment.
Beef cattle data from temperate (TEMP, n = 3947) and tropically adapted (TROP, n = 4137) breeds were analysed to compute estimates of genetic and phenotypic correlations between animal, abattoir carcass, and meat quality measures. Live animal traits included: liveweight (S2LWT), scanned subcutaneous rump fat depth (S2P8), scanned eye muscle area (S2EMA), flight time (S1FT), and finishing average daily gain (FADG). Carcass traits included: hot carcass weight (CWT), retail beef yield percentage (RBY), intramuscular fat percentage (IMF), subcutaneous rump fat depth (P8), eye muscle length by width (ELW), and meat colour score (MEATC). Meat quality measures taken on 2 muscles (M. longissimus thoracis et lumborum (LTL) and M. semitendinosus (ST)) included: shear force of LTL (LTL_SF) and ST (ST_SF); compression of the ST (ST_C); cooking loss % of the LTL (LTL_CL%) and ST (ST_CL%); Minolta LTL L* (LTL_L*), a* (LTL_a*), ST a* (ST_a*); and consumer-assessed LTL tenderness score (LTL_TEND). Genetic and phenotypic correlations between animal measures and related carcass traits were moderate to very high for TEMP and TROP. Genetic correlations between S2LWT and CWT were 0.89 and 0.82, between S2P8 and P8 0.80 and 0.88, and between S2EMA and ELW 0.62 and 0.68, for TEMP and TROP, respectively. Genetic correlations between animal measures and other carcass traits varied; moderate genetic correlations were estimated between S2P8 and RBY (-0.57, -0.19 for TEMP, TROP) and S2P8 and IMF (0.39, 0.23 for TEMP, TROP). Genetic correlations between animal and meat quality measures were moderate to low. For TEMP, moderate genetic correlations were estimated between S2P8 and LTL_TEND (0.38), FADG and ST_a* (-0.49), and FADG and LTL_TEND (0.45); and for TROP, S1FT and LTL_SF (-0.54), and S2EMA and LTL_L* (-0.46). Phenotypic correlations between animal and meat quality were generally low and close to zero. Several moderate to high genetic correlations existed between carcass and meat quality traits. In general, fatness measures were genetically correlated with tenderness (e.g. IMF and LTL_TEND 0.61, 0.31 for TEMP, TROP). CWT was genetically correlated with meat colour (CWT and LTL_L* 0.66, 0.60 for TEMP, TROP) and objective tenderness measures (CWT and ST_C -0.52, -0.22 for TEMP, TROP). Once again phenotypic correlations between carcass and meat quality were low, indicating that few phenotypic predictors of meat quality traits were identified. Several of the genetic correlations show that both animal and abattoir carcass traits may be of use as indirect measures for carcass and meat quality traits in multiple trait genetic evaluation systems.
The steer progeny of sires genetically diverse for fatness and meat yield were grown at different rates from weaning to feedlot entry and effects on growth, carcass and meat-quality traits were examined. The present paper, the second of a series, reports the effects of genetic and growth treatments on carcass traits. A total of 43 sires, within three 'carcass class' categories, defined as high potential for meat yield, marbling or both traits, was used. Where available, estimated breeding values for the carcass traits of retail beef yield (RBY%) and intramuscular fat (IMF%) were used in selection of the sires, which were drawn from Angus, Charolais, Limousin, Black Wagyu and Red Wagyu breeds,toprovidearangeofcarcasssiretypesacrossthethreecarcassclasses.SteerprogenyofHereforddamsweregrownat either conventional (slow: ~0.5 kg/day) or accelerated (fast: ~0.7 kg/day) rates from weaning to feedlot entry weight, with group means of ~400 kg. Accelerated and conventionally grown groups from successive calvings were managed to enter the feedlot at similar mean feedlot entry weights at the same time for the 100-day finish under identical conditions. Faster-backgrounded groups had greater fat levels in the carcass than did slower-backgrounded groups. Dressing percentages and fat colour were unaffected by growth treatment, whereas differences in ossification score and meat colour were explained by age at slaughter. There were significant effects of sire type for virtually all carcass traits measured in the progeny. Differences in hot standard carcass weight showed a clear advantage to European types, with variableoutcomesfortheAngusandWagyuprogeny.Sireselectionbyestimatedbreedingvalues (withintheAngusbreed) foryield and/orfat traits resultedinexpecteddifferencesintheprogenyforthose traits. Therewerelarge differencesinboth meat yield and fatness among the types of greatest divergence in genetic potential for those traits, with the Black Wagyu and the Angus IMF clearly superior for IMF%, and the European types for RBY%. The Angus IMF progeny performed as well as that of the Black Wagyu for all fatness traits. Differences in RBY% among types were generally reflected by similar differences in eye muscle area. Results here provide guidelines for selecting sire types to target carcass traits for specific markets. The absence of interactions between growth and genetic treatments ensures that consistent responses can be expected across varying management and production systems.
This review concentrates on factors influencing the nutritive value of cereal
grains for animals and strategies, in particular processing and storage, which
may be used to optimise fermentation and digestion. The main focus is on the
utilisation of starch in cereal grains by ruminants. Extensive comparisons
have been made between grains and between animals to understand the reasons
for differences in pattern of fermentation and/or intestinal digestion in
response to a range of processing techniques. In addition, differences between
the animal species have been reviewed to understand further the factors
critical for maximising post-ruminal starch digestion.
This review describes the pattern of intramuscular fat accretion in cattle and the potential for its manipulation during both the pasture (or backgrounding) and intensive grain-finishing phases of development. A growth curve for the development of marbling in British and Japanese Black type breeds is discussed with the conclusion that 3 phases of development exist: (i) a period of growth up to ~200 kg hot carcass weight where intramuscular fat does not increase; (ii) a period of linear development as carcass weight increases from 200 to 450 kg; and (iii) the attainment of mature body size (~500 kg carcass weight depending on genotype) at which intramuscular fat content appears to reachea maximum. Data are also presented to show that the intramuscular and other fat depots develop at similar rates indicating that intramuscular fat is not a late maturing depot. Pre-finishing growth checks reduce the initial intramuscular fat at the start of finishing and this is translated into lower levels at the end of finishing. It is argued that the greatest potential for the manipulation of intramuscular fat accretion during fattening is via an increase in the net energy of the ration. Increasing net energy can be achieved by increasing the cereal grain content of the diet (grain v. grass); by feeding processed cereal grain, which allows both maximal rumen fermentation and small intestinal digestion of starch, and by increasing the lipid content of the diet. In addition it is proposed that the substrate supply or hormonal milieu can also be optimised, along with the availability of net energy to maximise fat accretion. The role of lipolysis (fat turnover) as a regulator of fat accretion is also discussed.
Cattle sired by Piedmontese or Wagyu bulls were bred and grown within pasture-based nutritional systems followed by feedlot finishing. Effects of low (mean 28.6 kg, n = 120) and high (38.8 kg, n = 120) birthweight followed by slow (mean 554 g/day, n = 119) or rapid (875 g/day, n = 121) growth to weaning on beef primal cut weights at ~30 months of age were examined. Cattle of low birthweight or grown slowly to weaning had smaller primal cuts at 30 months as a result of reduced liveweight and smaller carcasses compared with their high birthweight or rapidly grown counterparts. Hence they require additional nutritional and economic inputs to reach target market weights. At equivalent carcass weights (380 kg), cattle restricted in growth from birth to weaning yielded slightly more beef and were somewhat leaner than their rapidly grown counterparts, resulting in primal cuts being up to 4% heavier in the slowly grown compared with the rapidly grown cattle. Compositional differences due to birthweight were less apparent at the same carcass weight, although low birthweight cattle had a slightly (~2%) heavier forequarter and slightly lower (~1%) hindquarter retail yield, and less shin-shank meat (~2%) than high birthweight cattle, suggesting only minor effects on carcass tissue distribution. There were few interactions between sire genotype and birthweight or preweaning growth, and interactions between birthweight and preweaning growth were not evident for any variables. However, variability between cohorts in their long-term responses to growth early in life suggests other environmental factors during early-life and/or subsequent growth influenced carcass yield characteristics. Overall, this study shows that effects of birthweight and preweaning growth rate on carcass compositional and yield characteristics were mostly explained by variation in carcass weight and, hence, in whole body growth to 30 months of age.
Cattle sired by Piedmontese or Wagyu bulls were bred and grown within pasture-based nutritional systems followed by feedlot finishing. Effects of low (mean 28.6 kg, n = 120) and high (38.8 kg, n = 120) birth weight followed by slow (mean 554 g/day, n = 119) or rapid (875 g/day, n = 121) growth to weaning on carcass, yield and beef quality characteristics at about 30 months of age were examined. Low birth weight calves weighed 56 kg less at 30 months of age, had 32 kg lighter carcasses, and yielded 18 kg less retail beef compared with high birth weight calves. Composition of carcasses differed little due to birth weight when adjusted to an equivalent carcass weight (380 kg). Calves grown slowly to weaning were 40 kg lighter at 30 months of age compared with those grown rapidly to weaning. They had 25 kg smaller carcasses which yielded 12 kg less retail beef than their counterparts at 30 months of age, although at an equivalent carcass weight yielded 5 kg more retail beef and had 5 kg less fat trim. Neither low birth weight nor slow growth to weaning had adverse effects on beef quality measurements. No interactions between sire-genotype and birth weight, or growth to weaning, were evident for carcass, yield and beef quality traits. Although restricted growth during fetal life or from birth to weaning resulted in smaller animals that yield less meat at about 30 months of age, adverse effects on composition due to increased fatness, or on indices of beef quality, were not evident at this age or when data were adjusted to an equivalent carcass weight.
This paper reviews results of studies on effects of fetal programming and maternal nutrition during pregnancy on growth, efficiency, carcass, muscle, and meat quality characteristics of cattle. It includes results from our Australian Beef Cooperative Research Centre studies on factors such as chronic severe nutritional restriction from approximately d 80 of pregnancy to parturition and(or) throughout lactation used to create early-life growth differences in the offspring of cows within pasture-based systems and the effect of these treatments on production characteristics to 30 mo of age. Fetal programming and related maternal effects are most pronounced, and explain substantial amounts of variation, for growth-related production characteristics such as BW, feed intake, carcass weight, muscle weights, meat yield, and fat and bone weights at any given age, but are less evident when assessed at the same body and carcass weights. Some effects of maternal and early-life factors in our studies were evident for efficiency traits, but fewer affected beef quality characteristics at 30 mo of age, explaining only small amounts of variation in these traits. It is difficult to uncouple maternal nutritional effects specific to prenatal life from those that carry over to the postnatal period until weaning, particularly the effects of maternal nutrition during pregnancy on subsequent lactational performance. Hence, experimental design considerations for studying fetal programming effects on offspring during later life are discussed in relation to minimizing or removing prenatal and postnatal confounding effects. The relative contribution of fetal programming to the profitability of beef production systems is also briefly discussed. In this regard, the importance of health and survival of cows and calves, the capacity of cows to re-breed in a timely manner and the efficiency with which feed and other resources are utilized cannot be overemphasized in relation to economic, welfare and environmental considerations.
Beef cattle are raised for their lean tissue, and excessive fat accumulation accounts for large amounts of waste. On the other hand, intramuscular fat or marbling is essential for the palatability of beef. In addition, tender beef is demanded by consumers, and connective tissue contributes to the background toughness of beef. Recent studies show that myocytes, adipocytes, and fibroblasts are all derived from a common pool of progenitor cells during embryonic development. It appears that during early embryogenesis, multipotent mesenchymal stem cells (MSC) first diverge into either myogenic or adipogenic-fibrogenic lineages; myogenic progenitor cells further develop into muscle fibers and satellite cells, whereas adipogenic-fibrogenic lineage cells develop into the stromal-vascular fraction of skeletal muscle where resides adipocytes, fibroblasts and resident fibro-adipogenic progenitor cells (FAP, the counterpart of satellite cells). Strengthening myogenesis (i.e., formation of muscle cells) enhances lean growth, promoting intramuscular adipogenesis (i.e., formation of fat cells) elevates marbling, and reducing intramuscular fibrogenesis (i.e., formation of fibroblasts and synthesis of connective tissue) improves overall tenderness of beef. Because the abundance of progenitor cells declines as animals age, it is more effective to manipulate progenitor cell differentiation at an early developmental stage. Nutritional, environmental and genetic factors shape progenitor cell differentiation; however, up to now, our knowledge regarding mechanisms governing progenitor cell differentiation remains rudimentary. In summary, altering mesenchymal progenitor cell differentiation through nutritional management of cows, or fetal programming, is a promising method to improve cattle performance and carcass value.
Meat quality measures, including objective measures of tenderness (shear force and compression), were taken on 2 muscles [M. longissimus thoracis et lumborum (LTL) and M. semitendinosus (ST)] from 7566 carcasses from temperate (TEMP) and tropically adapted (TROP) beef cattle breeds. Animals were finished to 1 of 3 market carcass weight end-points (220, 280, or 340 kg) either on pasture or in a feedlot, and in 2 different geographic regions for TROP. Both the phenotypic and genetic expressions of the traits were estimated at each market weight and for each finishing regime. Heritabilities and correlations between the traits were estimated for TEMP and TROP separately. Smaller additive variances and heritabilities were observed for temperate breeds compared with tropically adapted breeds for most of the traits studied. For TROP, the heritability of traits measured on the ST muscle [compression (ST_C), shear force (ST_SF), and L* Minolta lightness value (ST_L*)] was 0.27, 0.42, and 0.16, respectively, and for traits measured on the LTL muscle [compression (LTL_C), shear force (LTL_SF), L* Minolta lightness value (LTL_L*), a* Minolta redness value (LTL_a*), cooking loss % (LTL_CL%), and consumer assessed tenderness score (LTL_TEND)] 0.19, 0.30, 0.18, 0.13, 0.20, and 0.31, respectively. For TEMP, the heritability of traits measured on the ST muscle [ST_C, ST_SF, ST_L*, a* Minolta redness value (ST_a*), cooking loss % (ST_CL%)] was 0.12, 0.11, 0.17, 0.13, and 0.15, respectively, and of traits measured on the LTL muscle (LTL_C, LTL_SF, LTL_L, and LTL_TEND) 0.08, 0.09, 0.17 and 0.18, respectively. Genetic correlations were moderate to high for tenderness measures (shear force and compression) between muscles for the same tenderness measure (e.g. LTL_SF and ST_SF was 0.46 for TROP) and within a muscle for the different measures (e.g. ST_C and ST_SF was 0.83 for TROP). Phenotypic and genetic correlations between LTL_L* and all objective measures of tenderness were negative (e.g. LTL_SF and LTL_L* for TROP was –0.40). The genetic relationship between LTL_SF and LTL_TEND was –0.79 and –0.49 for TROP and TEMP, respectively. Finishing system affected the phenotypic expression of all traits. Pasture-finished, compared with feedlot-finished, animals had higher shear force and compression measures, darker meat colour, and lower sensory tenderness scores for both TEMP and TROP. For TROP, heifers had higher shear force and compression measures, lower sensory tenderness scores, and darker meat colour (lower L* values) than steers. Genetic correlations between markets were generally high and close to unity with the exception of the ST_L*, LTL_L*, ST_C, and ST_SF for TEMP. Geographic region had little effect on the phenotypic and genetic expression of meat quality traits for TROP. Genetic correlations between finishing regimes for all traits were positive and close to unity, with the exception of ST_C and LTL_SF for TEMP, and LTL_L* and LTL_CL% for TROP. Genetic improvement of meat quality traits is a possibility for tropically adapted breeds given the moderate heritabilities, adequate phenotypic variance, generally favourable genetic correlations between traits, and little evidence of genotype by environment interactions. A R 0 2 0 8 7 G e n e t i c a n d n o n -g e n e t i c e f f e c t s o n b e e f q u a l i t y D . J . J o h n s t o n e t a l .
Severe, chronic growth retardation of cattle early in life reduces growth potential, resulting in smaller animals at any given age. Capacity for long-term compensatory growth diminishes as the age of onset of nutritional restriction resulting in prolonged growth retardation declines. Hence, more extreme intrauterine growth retardation can result in slower growth throughout postnatal life. However, within the limits of beef production systems, neither severely restricted growth in utero nor from birth to weaning influences efficiency of nutrient utilisation later in life. Retail yield from cattle severely restricted in growth during pregnancy or from birth to weaning is reduced compared with cattle well grown early in life, when compared at the same age later in life. However, retail yield and carcass composition of low- and high-birth-weight calves are similar at the same carcass weight. At equivalent carcass weights, cattle grown slowly from birth to weaning have carcasses of similar or leaner composition than those grown rapidly. However, if high energy, concentrate feed is provided following severe growth restriction from birth to weaning, then at equivalent weights post-weaning the slowly-grown, small weaners may be fatter than their well-grown counterparts. Restricted prenatal and pre-weaning nutrition and growth do not adversely affect measures of beef quality. Similarly, bovine myofibre characteristics are little affected in the long term by growth in utero or from birth to weaning. Interactions were not evident between prenatal and pre-weaning growth for subsequent growth, efficiency, carcass, yield and beef-quality characteristics, within our pasture-based production systems. Furthermore, interactions between genotype and nutrition early in life, studied using offspring of Piedmontese and Wagyu sired cattle, were not evident for any growth, efficiency, carcass, yield and beef-quality parameters. We propose that within pasture-based production systems for beef cattle, the plasticity of the carcass tissues, particularly of muscle, allows animals that are growth-retarded early in life to attain normal composition at equivalent weights in the long term, albeit at older ages. However, the quality of nutrition during recovery from early life growth retardation may be important in determining the subsequent composition of young, light-weight cattle relative to their heavier counterparts. Finally, it should be emphasised that long-term consequences of more specific and/or acute environmental influences during specific stages of embryonic, foetal and neonatal calf development remain to be determined. This need for further research extends to consequences of nutrition and growth early in life for reproductive capacity.
Intramuscular fat (IMF) content plays a key role in various quality traits of meat. IMF content varies between species, between breeds and between muscle types in the same breed. Other factors are involved in the variation of IMF content in animals, including gender, age and feeding. Variability in IMF content is mainly linked to the number and size of intramuscular adipocytes. The accretion rate of IMF depends on the muscle growth rate. For instance, animals having a high muscularity with a high glycolytic activity display a reduced development of IMF. This suggests that muscle cells and adipocytes interplay during growth. In addition, early events that influence adipogenesis inside the muscle (i.e proliferation and differentiation of adipose cells, the connective structure embedding adipocytes) might be involved in interindividual differences in IMF content. Increasing muscularity will also dilute the final fat content of muscle. At the metabolic level, IMF content results from the balance between uptake, synthesis and degradation of triacylglycerols, which involve many metabolic pathways in both adipocytes and myofibres. Various experiments revealed an association between IMF level and the muscle content in adipocyte-type fatty acid-binding protein, the activities of oxidative enzymes, or the delta-6-desaturase level; however, other studies failed to confirm such relationships. This might be due to the importance of fatty acid fluxes that is likely to be responsible for variability in IMF content during the postnatal period rather than the control of one single pathway. This is evident in the muscle of most fish species in which triacylglycerol synthesis is almost zero. Genetic approaches for increasing IMF have been focused on live animal ultrasound to derive estimated breeding values. More recently, efforts have concentrated on discovering DNA markers that change the distribution of fat in the body (i.e. towards IMF at the expense of the carcass fatness). Thanks to the exhaustive nature of genomics (transcriptomics and proteomics), our knowledge on fat accumulation in muscles is now being underpinned. Metabolic specificities of intramuscular adipocytes have also been demonstrated, as compared to other depots. Nutritional manipulation of IMF independently from body fat depots has proved to be more difficult to achieve than genetic strategies to have lipid deposition dependent of adipose tissue location. In addition, the biological mechanisms that explain the variability of IMF content differ between genetic and nutritional factors. The nutritional regulation of IMF also differs between ruminants, monogastrics and fish due to their digestive and nutritional particularities.
It is well documented that grain feeding stimulates adipogenesis in beef cattle, whereas pasture feeding depresses the development of adipose tissues, including intramuscular (i.m.) adipose tissue. Additionally, production practices that depress adipocyte differentiation also limit the synthesis of MUFA. Marbling scores and MUFA increase in parallel suggesting that stearoyl-coenzyme A desaturase (SCD) gene expression is closely associated with and necessary for marbling adipocyte differentiation. Similarly, marbling scores and fatty acid indices of SCD activity are depressed in response to dietary vitamin A restriction. In bovine preadipocytes, vitamins A and D both decrease glycerol-3-phosphate dehydrogenase (GPDH) activity, an index of adipocyte differentiation, whereas incubation of bovine preadipocytes with l-ascorbic acid-2-phosphate increases GPDH activity. Exposing bovine preadipocytes to zinc also stimulates adipogenesis, putatively by inhibiting nitric oxide (NO) production. However, incubation of bovine preadipocytes with arginine, a biological precursor of NO, strongly promotes differentiation in concert with increased SCD expression. This suggests that the effect of either arginine or zinc on adipogenesis is independent of NO synthesis in bovine preadipocytes. Enhanced expression of SCD is associated with a greater accumulation of MUFA both in bovine preadipocyte cultures and during development in growing steers. In bovine preadipocytes, trans-10, cis-12 CLA strongly depresses adipocyte differentiation and SCD gene expression, thereby reducing MUFA concentrations. The bovine preadipocyte culture studies suggest that any production practice that elevates vitamins A or D or trans-10, cis-12 CLA in bovine adipose tissue will reduce i.m. adipose tissue development. Conversely, supplementation with vitamin C or zinc may promote the development of i.m. adipose tissue.
Deposition of intramuscular fat, or "marbling," in beef cattle contributes significantly to meat quality variables, including juiciness, flavor, and tenderness. The accumulation of intramuscular fat is largely influenced by the genetic background of cattle, as well as their age and nutrition. To identify genes that can be used as early biomarkers for the prediction of marbling capacity, we studied the muscle transcriptome of 2 cattle crossbreeds with contrasting intramuscular fat content. The transcriptomes of marbling LM tissue of heifers from Wagyu x Hereford (WxH; n = 6) and Piedmontese x Hereford (PxH; n = 7) crosses were profiled by using a combination of complementary DNA microarray and quantitative reverse transcription-PCR. Five biopsies of LM were taken from each animal at approximately 3, 7, 12, 20, and 25 mo from birth. Tissue was also collected from the LM of each animal at slaughter (approximately 30 mo). Microarray experiments, conducted on the first 3 biopsies of 2 animals from each crossbreed, identified 97 differentially expressed genes. The gene expression results indicated that the LM transcriptome of animals with high marbling potential (WxH) could be reliably distinguished from less marbled animals (PxH) when the animals were as young as 7 mo of age. At this early age, one cannot reliably determine meaningful differences in intramuscular fat deposition. We observed greater expression of a set of adipogenesis- and lipogenesis-related genes in the LM of young WxH animals compared with their PxH contemporaries. In contrast, genes highly expressed in PxH animals were associated with mitochondrial oxidative activity. Further quantitative reverse transcription-PCR experiments revealed that the messenger RNA of 6 of the lipogenesis-related genes also peaked at the age of 20 to 25 mo in WxH animals. The messenger RNA expression of ADIPOQ, SCD, and THRSP was highly correlated with intramuscular fat content of an individual in WxH animals. Our study provides clear evidence of early molecular changes associated with marbling and also identifies specific time frames when intramuscular fat development in cattle muscle can be detected by using gene expression. This information could be used by animal scientists to design optimal nutrition for high marbling potential. In addition, the genes found to be highly expressed during development of marbling could be used to develop genetic markers or biomarkers to assist with beef production strategies.
Intramuscular adipose tissue from the fifth-eighth thoracic vertebrae region of the longissimus dorsi muscle, and portions of the overlying subcutaneous adipose tissue, were obtained at 16 and 18 months of age from Angus steers fed ad libitum either a corn silage (low energy) or ground corn (high energy) diet. Carcass weight, backfat thickness, and kidney, pelvic and heart fat were significantly greater in the steers fed the high energy diet; however, there were no significant differences in marbling scores between diet groups. Additionally, feeding steers the high energy diet did not result in differences in adipocyte diameter or number of adipose cells per gram tissue in either adipose tissue depot. Intramuscular adipocytes had a peak diameter (the diameter represented by the greatest number of cells) of 104 +/- 2 microns; peak diameter in subcutaneous adipose tissue was 141 +/- 5 microns. The activities of ATP-citrate lyase and NADP-malate dehydrogenase increased with age in the subcutaneous adipose tissue; feeding steers the high energy diet increased enzyme activities further. Age and diet had no effect on enzyme activities in intramuscular adipose tissue. A similar pattern was observed for the incorporation of lipogenic precursors into fatty acids. Acetate provided 70-80% of the acetyl units to in vitro lipogenesis in subcutaneous adipose tissue, but only 10-25% in intramuscular adipose tissue. Conversely, glucose provided 1-10% of the acetyl units in subcutaneous adipose tissue, but 50-75% in the intramuscular depot.(ABSTRACT TRUNCATED AT 250 WORDS)
Beef steers were fed in two phases 1) to determine the relative importance of changes in DMI, gastrointestinal tract fill, energy expenditures, and composition of gain in the compensatory growth phenomenon, 2) to compare the effects of growth restriction due to ad libitum consumption of a low-energy (low-concentrate) diet to those of limited intake of a high-energy (high-concentrate) feed, and 3) to examine changes in carcass composition and quality resulting from different types of growth restriction. During the growing phase (237 to 327 kg), steers were fed either a high- (C) of low- (F) concentrate diet. Diet F was available for ad libitum consumption (FA) and diet C was available either for ad libitum consumption (CA) or on a limited basis (CL) to match the live weight gains by the FA group. During the finishing phase (327 to 481 kg), all steers received diet C, either for ad libitum consumption (CA) or restricted (CL) to 70% of the intake by the corresponding CA steers. Backfat thickness was markedly reduced (P < .001) by final feed restriction (7.4 and 6.9 mm for CL-CL and FA-CL respectively), compared with CA-CA (12.6 mm). Backfat also was lower in CL-CA (11.6 mm, P < .10) and FA-CA (9.9 mm, P < .05) than in CA-CA steers. Conversely, marbling scores were similar among groups, except for the FA-CL steers, which had lower marbling scores than FA-CA and CL-CA steers (P < .05). Higher DMI following growth restriction were accompanied by increased rates of live weight (+54 and +27%) and empty body weight (EBW; +57 and +43%) gain for CL-CA and FA-CA steers, respectively, compared with CA-CA steers. Gain:feed (EBW basis) were improved in some restricted/refed groups (+30, +13, and +10%, for Cl-CA, CL-CM respectively CA-CA. Increased DMI played a major role in the compensatory gain response in both CL-CA and FA-CA groups. Maintenance requirement was reduced (-17%) in CL-CA and increased in the FA-CA group (+21%); both changes affected the magnitude of compensatory gain in those animals. In contrast, composition of gain had little or no effect on the compensatory gain response. Programmed feeding can be used to manipulate carcass quality, but low-concentrate feeding during the growing phase may impair overall feedlot performance.
Angus (n = 8; 210 kg of BW) and 7/8 Wagyu (n = 8; 174 kg of BW) steers were used to evaluate the effects of dietary energy source on muscle and adipose tissue metabolism and insulin sensitivity. Steers were assigned to either a grain-based (corn) or hay-based (hay) diet and fed to similar final BW. At slaughter, LM and s.c. and i.m. adipose tissue samples were collected. Portions of the LM and adipose tissues were placed immediately in liquid N for later measurement of glycolytic intermediates. Fresh LM and s.c. and i.m. adipose tissues were incubated with [U-(14)C]glucose to assess glucose metabolism in vitro. All in vitro measures were in the presence of 0 or 500 ng/mL of insulin. Also, s.c. and i.m. adipose tissues were incubated with [1-(14)C]acetate to quantify lipid synthesis in vitro. Glucose-6-phosphate and fructose-6-phosphate concentrations were 12.6- and 2.4-fold greater in muscle than in s.c. and i.m. adipose tissues, respectively. Diet did not affect acetate incorporation into fatty acids (P = 0.86). Insulin did not increase conversion of glucose to CO(2), lactate, or total lipid in steers fed hay but caused an increase (per cell) of 97 to 110% in glucose conversion to CO(2), 46 to 54% in glucose conversion to lactate, and 65 to 160% in glucose conversion to total lipid content in adipose tissue from steers fed corn. On a per-cell basis, s.c. adipose tissue had 37% greater glucose oxidation than i.m. adipose (P = 0.04) and 290% greater acetate incorporation into fatty acids than i.m. adipose (P = 0.04). Insulin addition to s.c. adipose tissue from corn-fed steers failed to stimulate glucose incorporation into fatty acids, but exposing i.m. adipose tissue from corn-fed steers to insulin resulted in a 165% increase in glucose incorporation into fatty acids. These results suggest that feeding hay limited both glucose supply and tissue capacity to increase glucose utilization in response to insulin without altering acetate conversion to fatty acids. Because s.c. adipose tissue consistently utilized more acetate and oxidized more glucose than did i.m. adipose, these results suggest that hay-based diets may alter i.m. adipose tissue metabolism with less effect on s.c. adipose tissue.
The objectives of this study were to assess the effects of early grain feeding on acetate and glucose turnover rates and acetate and glucose preference for palmitate synthesis by subcutaneous fat (SCF), intramuscular fat (IMF), and visceral fat (VF) in finishing steers. Sixteen Angus × Simmental steers were used in the study; 8 were early weaned (EW) and fed a high-grain diet immediately after weaning for 100 or 148 d, and 8 remained with their dams on pasture until weaning at 202 ± 5 or 253 ± 5 d of age. Normal weaned (NW) and EW animals were combined and grazed to 374 ± 5 or 393 ± 5 d of age, when they were placed on a corn silage–based finishing ration until they achieved a SCF thickness of 1.0 to 1.2 cm (494 ± 17 d of age for EW steers and 502 ± 12 d of age for NW steers). Immediately before harvest, steers were continuously infused for 12 h with [2H3] acetate (1.63 mmol/min; n = 8) or [U-13C6] glucose (0.07 mmol/min; n = 8). Blood samples were collected before initiation of infusions and at the end of the infusion from 8 animals or at 1-h intervals for the first 11 h and at 15-min intervals for the last hour of infusion for the other 8 animals. Adipose tissue samples from SCF, IMF, and VF depots were collected at harvest, and lipids were extracted. Plasma enrichments of acetate and glucose and palmitate enrichment in each depot were used to calculate plasma turnover rates and fractional synthesis rates (FSR; % per h) of palmitate from each isotope. Early weaned steers had greater marbling scores compared to NW steers (P < 0.05). Plasma turnover rates and FSR for EW and NW steers were similar except for SCF, where a greater FSR from acetate was observed for EW steers. It is possible the greater FSR for SCF was due to harvesting the animals at a slightly more advanced stage of conditioning as evidenced by the trend for greater 12th rib fat (P = 0.07). Plasma acetate turnover and palmitate FSR from acetate were much greater (P < 0.05) than the corresponding rates from glucose, supporting the primary role of acetate as an energy source and the primary substrate for lipid synthesis across fat depots. However, FSR from acetate and glucose were not different among depots, suggesting that any potential effects of dietary starch on differential deposition of energy in SCF and IMF are not substrate driven. © 2015 American Society of Animal Science. All rights reserved.
Angus and Angus × Simmental calves (steers, n = 131; heifers, n = 69) were randomly allotted to 1 of 5 dietary treatments at 2 locations: early-wean starch; early-wean fiber; creep-fed starch; creep-fed fiber; or normal-wean, no-creep control. Early-weaned calves (133 ± 21 d of age) were placed in the feedlot, whereas normal-weaned calves remained with their dams on pasture (2 or 3 replications/location). Creep feed was offered for ad libitum DMI to calves fed creep-fed starch and creep-fed fiber. In the growing phase, early-wean-starch calves had 15% lower DMI and were 13% more efficient than early-wean-fiber calves (P < 0.01). In the finishing phase, creep-fed calves gained 9% more, had 7% lower DMI, and were 16% more efficient (P < 0.01) than early-weaned calves. Control calves were 5% more efficient but spent 19 more days on feed (P < 0.01) than did calves on the other treatments. Marbling score was greater for early-weaned calves when compared with creep-fed calves (586 vs. 500, P < 0.01). Retained-ownership profit was $38.28 greater for the early-wean-fiber treatment than for the early-wean-starch treatment (P = 0.04), $61.47 greater for creep-fed calves than for early-weaned calves (P < 0.01), and $37.89 greater for control (P < 0.01) compared with other treatments. Early weaning and creep feeding increased carcass quality and growing-phase BW gains but reduced profits. Calves fed coproduct feeds during the growing phase achieved similar BW gains and carcass traits as calves fed corn-based diets and were more profitable.
This paper describes the methodology used for the collection of carcass yield and meat quality data from straightbred and crossbred cattle in the Cooperative Research Centre for Cattle and Beef Quality core program.
The BeefSpecs fat calculator is a decision-support system developed to assist decision making on-farm to improve compliance rates with beef carcass specifications. BeefSpecs is underpinned by a research model run in conjunction with a translation process that converts inputs recorded in live animal and carcass assessment language into research model parameters. In contrast to many other research modelling systems, the changes in body composition predicted by the research model that underpins BeefSpecs are driven by growth rate. Use of this model removes the need for information concerning feed intake and dietary characteristics, which are impractical to collect on a routine basis in commercial production systems. A translation process was developed to use traits that are recorded routinely on-farm during normal production activities while allowing the original modelling system to run efficiently and accurately. This process aligns BeefSpecs with the language used by industry and increases the confidence of users in the underlying model theories. The outputs produced by BeefSpecs include final liveweight, final subcutaneous fat depth and hot standard carcass weight at the end of a specified feeding period. These traits contribute to the carcass specifications used to determine carcass value in the domestic and international markets supplied by the Australian beef industry, which directly aligns BeefSpecs with the decision-making styles of beef producers. During the development of BeefSpecs, potential users were consulted and enlisted in the evaluation process.
The present study investigates the effects of backgrounding and finishing growth rates of Bos taurus steers grown out on three post-weaning growth pathways, across 4 years (1995–1998) on fat deposition. Scanned P8 fat at backgrounding exit (SP8exit), scanned P8 fat before slaughter (SP8sla) and carcass intramuscular fat (IMF, %) were evaluated. Four equations to predict SP8sla and four equations to predict carcass IMF across years were developed. Three post-weaning growth pathways (GPs) generated by different nutritional treatments across years were used in the study. Growth pathways were created by backgrounding steers on pasture with no supplementation (GP1), pasture plus supplementary feeding formulated pellets (GP2) or pasture with access to a forage crop (GP3). The steers were then finished in a feedlot or on pasture to slaughter weights of 520 kg (Korean market specification) or 600 kg (Japanese market specification). Cubic smoothing splines were fitted to the liveweight of all animals from the start of backgrounding until slaughter. Backgrounding growth rates were interpolated off the GP curves and the mean average daily gain (ADG, kg/day) at Day 100 (D100, Days 100–91 before relocation to the finishing phase), and Day 150 (D150, Days 150–141 before relocation to the finishing phase) were calculated. Significant (P < 0.01) differences between SP8exit and backgrounding ADG (BADG) were detected in all years except GP2 v. GP3 in 1997. GP1 steers had the lowest BADG across all years, ranging from 0.39 to 0.88 kg/day. At backgrounding exit, the mean SP8exit for the different GPs was ranked, with GP1 < GP3 for all years, with significant (P < 0.01) differences among GP1, GP2 and GP3 in all years except 1996. At the end of finishing, the mean carcass IMF over all years and finish (pasture and feedlot) (P < 0.05) was 4.71% for GP1 v. 5.09% for GP3 for Korean market steers and the mean SP8sla (P < 0.01) was 14.59 mm for GP1 v. 16.04 mm for GP3 and the mean carcass IMF (P < 0.01) was 5.54% for GP1 v. 6.27% for GP3 for Japanese market steers. The residual correlation of the multivariate response variables, namely, D100, D150 and BADG v. SP8exit (n = 1054), SP8sla (n = 1049) and carcass IMF (n = 1002), indicated that the highest correlations, all significant (P < 0.01), were 0.33, 0.20 and 0.12 for BADG v. SP8exit, SP8sla and carcass IMF, respectively. The residual variances (mm2) of the four SP8sla equations were 6.14, 7.44, 8.72 and 10.73 for 1995, 1996, 1997 and 1998, respectively, and the residual variances (%2) for the four carcass IMF equations were 2.51, 2.26, 1.75 and 0.84, for 1995, 1996, 1997 and 1998, respectively.
cattle partitioning of fat among depots, and carcass characteristics of growing-finishing beef Effect of rate of body weight gain in steers during the stocker phase. I. Growth, doi: 10.2527/jas.2012-5440 originally published online July 12, 2013 2013, 91:4322-4335. J ANIM SCI4322 the World Wide Web at: The online version of this article, along with updated information and services, is located on www.asas.org by Andrea Garmyn on January 24, 2014 www.journalofanimalscience.org Downloaded from by Andrea Garmyn on January 24, 2014 www.journalofanimalscience.org Downloaded from
Advances in mammalian genomics have permitted the application of gene expression profiling approaches to gene discovery for meat quality traits in cattle. The first custom cDNA microarray based on the transcriptome of bovine muscle and fat tissue was developed and applied to animal experimentation and cell culture experimentation between 1999 and 2005. Complementary DNA microarray tools for beef quality research were developed in parallel with bioinformatics tools that permit the analysis of microarray data obtained from complex experimental designs commonly encountered in large animal research. In addition, tools were designed to link gene expression data with gene function in the bovine, such as in vitro models of bovine adipogenesis and bioinformatics tools to map gene networks from expression data. The application of these genomics tools to the study of beef quality has yielded novel knowledge of genes and molecules involved in the processes of intramuscular adipogenesis and protein turnover. This review summarises the current state of knowledge and important lessons derived from bovine genomics initiatives in Australia and around the world.
Genetic evaluation for beef cattle in Australia has been performed using an animal model with best linear unbiased prediction since 1984. The evaluation procedures have evolved from simple to more complex models and from few to a large number of traits, including traits for reproduction, growth and carcass characteristics. This paper describes in detail the current beef cattle genetic evaluation system 'BREEDPLAN' used for the Australian beef cattle industry, the traits analysed and underlying models, and presents a short overview of the challenges and planned developments of coming years.
A total of 11 abattoir carcass measures were recorded on 7854 carcasses in temperate (TEMP) and tropically adapted (TROP) beef breeds. Breeds for TEMP included Angus, Hereford, Murray Grey, and Shorthorn; Brahman, Belmont Red, and Santa Gertrudis accounted for TROP breeds. Measurements included carcass weight (CWT), retail beef yield percentage (RBY), intramuscular fat percentage (IMF), subcutaneous fat depth at the P8 site (P8) and at 12/13th rib (RIB), eye muscle length by width (ELW), deep butt temperature (DBTEMP), fat colour score (FATC), meat colour score (MEATC), marbling score (MARB), and carcass muscle score (MUSC). Animals were finished to 3 different market weight endpoints, either on pasture or in a feedlot, and in different geographic regions for the TROP breeds. Both the phenotypic and genetic expressions of the traits were estimated at each level of market weight endpoint and finishing regime. Heritabilities (h2) and genetic (rg) and phenotypic (rp) correlations between traits were estimated for TEMP and TROP separately. The design effects of market weight endpoint and finishing regimes were the most important sources of variation for continuously measured traits. Main effects for the scored traits were finishing regime for FATC and MEATC and market weight endpoint for MARB and MUSC. Feedlot finished cattle had the whitest FATC and the lightest MEATC. For TEMP, estimates of h2 for CWT, RBY, IMF, P8, RIB, ELW, DBTEMP, FATC, MEATC, MARB, and MUSC were 0.39, 0.57, 0.38, 0.36, 0.27, 0.30, 0.10, 0.05, 0.11, 0.17, and 0.14, respectively. In comparison, h2 for the same order of traits for TROP were 0.36, 0.50, 0.39, 0.30, 0.41, 0.32, 0.04, 0.09, 0.11, 0.25, and 0.11. The direction and magnitude of rg between traits were similar for TEMP and TROP, particularly between CWT, RBY, IMF, P8, and RIB. Genetic correlations of RBY were moderate and negative with all measures of fatness, including IMF (-0.38 TEMP and -0.43 TROP). Positive rg existed between all measures of fatness, with MARB and IMF close to unity. Negative rg was estimated between CWT and all fat measurements. Also negative were the rg and rp estimates between CWT and MEATC. For all traits in both TEMP and TROP, domestic weight carcasses exhibited lower additive variance than export market carcasses. However, genetic correlations between traits across market weight endpoints were positive and close to unity, with the exception of RBY for TROP. For TEMP breeds, genetic correlations between finishing regimes were close to unity. However, possible genotype by environment interactions were found for TROP for P8, MEATC, and MARB between finishing in different geographic regions, and between feedlot and pasture finished animals for RBY and MEATC. Genetic improvement of carcass traits is a possibility given the moderate heritabilities, moderate to strong genetic correlations, and little evidence of genotype by environment interactions. AR0208 6 A. Re ver ter et al . Gene ti c and non- gene ti c ef fects on car cas s t rai ts
Beef cattle are raised for their lean, and excessive fat accumulation accounts for large amounts of waste. On the other hand, intramuscular fat or marbling is essential for the palatability of beef. In addition, tender beef is demanded by consumers, and connective tissue contributes to the background toughness of beef. Recent studies show that myocytes, adipocytes and fibroblasts are all derived from a common pool of progenitor cells during embryonic development. It appears that during early embryogenesis, multipotent mesenchymal stem cells (MSCs) first diverge into either myogenic or adipogenic/fibrogenic lineages; myogenic progenitor cells further develop into muscle fibers and satellite cells, while adipogenic/fibrogenic lineage cells develop into the stromal-vascular fraction of skeletal muscle where raise adipocytes, fibroblasts and resident fibro/adipogenic progenitor cells (FAPs, the counterpart of satellite cells). Strengthening myogenesis (formation of muscle cells) enhances lean growth, promoting intramuscular adipogenesis (formation of fat cells) elevates marbling, and reducing intramuscular fibrogenesis (formation of fibroblasts and synthesis of connective tissue) improves overall tenderness of beef. Nutritional, environmental and genetic factors shape progenitor cell differentiation; however, up to now, our knowledge regarding mechanisms governing progenitor cell differentiation remains rudimentary. In summary, altering mesenchymal progenitor cell differentiation through nutritional management of cows, or fetal programming, is a promising method to improve cattle performance and carcass value.
Special Edition Sheep and Cattle Production in New South Wales
The effect of growth path, as opposed to advancing age, on the biophysical and biochemical properties of muscle connective tissue was investigated. Nine-month old Brahman-cross steers were grown across either an uninterrupted path, or paths that incorporated weight-loss and then weight gain on two different diets: one group was realimented on pasture, whilst the other was realimented on a grain-based diet. Biophysical attributes of connective tissue toughness (Compression and Adhesion) in the semitendinosus muscle, were significantly reduced by treatment (P<0.05): weight loss with grain realimentation being the least tough in regard to the connective tissue component. Variance within the biophysical attributes was modelled statistically. Statistically significant models included terms for the post-slaughter connective tissue content as well as tissue contents of the enzymes lactate dehydrogenase and isocitrate dehydrogenase. The data suggest that biochemical measurements made up to 100 days prior to slaughter, may have value as indicators of final connective tissue toughness.
Mammary synthesis of milk fat continues to be an active research area, with significant advances in the regulation of lipid synthesis by bioactive fatty acids (FAs). The biohydrogenation theory established that diet-induced milk fat depression (MFD) in the dairy cow is caused by an inhibition of mammary synthesis of milk fat by specific FAs produced during ruminal biohydrogenation. The first such FA shown to affect milk fat synthesis was trans-10, cis-12 conjugated linoleic acid, and its effects have been well characterized, including dose-response relationships. During MFD, lipogenic capacity and transcription of key mammary lipogenic genes are coordinately down-regulated. Results provide strong evidence for sterol response element-binding protein-1 (SREBP1) and Spot 14 as biohydrogenation intermediate responsive lipogenic signaling pathway for ruminants and rodents. The study of MFD and its regulation by specific rumen-derived bioactive FAs represents a successful example of nutrigenomics in present-day animal nutrition research and offers several potential applications in animal agriculture.
Conjugated linoleic acid (CLA), a family of fatty acids found in beef, dairy foods and dietary supplements, reduces adiposity in several animal models of obesity and some human studies. However, the isomer-specific antiobesity mechanisms of action of CLA are unclear, and its use in humans is controversial. This review will summarize in vivo and in vitro findings from the literature regarding potential mechanisms by which CLA reduces adiposity, including its impact on (a) energy metabolism, (b) adipogenesis, (c) inflammation, (d) lipid metabolism and (e) apoptosis.
Metabolism of ruminant adipocytes involves the synthesis and mobilization of lipids. Rates of lipid synthesis from the uptake of preformed fatty acids (via lipoprotein lipase) and de novo synthesis of fatty acids are related to the energy balance. Acetate is the major carbon source for fatty acid synthesis with NADPH originating from the pentose cycle and the isocitrate cycle. Ruminant adipose tissue lacks the ability to utilize for lipogenesis those substrates that generate mitochondrial acetyl CoA because of an absence of ATP citrate-lyase and NADP-malate dehydrogenase. Lipid mobilization in ruminant adipocytes is apparently regulated via cAMP levels and a summary of the compounds investigated for lipolytic responses is presented. The control of lipid synthesis and mobilization is interrelated in ruminant adipose tissue. The coordinated manner in which these two functions are regulated is examined with regard to adipocyte responses to insulin and epinephrine. In both lipid synthesis and lipid mobilization, ruminant adipocytes are uniquely different from nonruminant adipose tissue. The physiological significance and possible basis for these species differences in adipose metabolism are discussed.
We used a 9.6 K cattle muscle/fat cDNA microarray to study gene expression differences between the longuissimus dorsi (LD) muscle of Japanese Black (JB) and Holstein (HOL) cattle. JB cattle exhibit an unusual ability to accumulate intramuscular adipose tissue with fat melting points lower than that in other breeds. The LD biopsies from three JB (Tajima strain) and three HOL animals were used in this breed comparison. Seventeen genes were identified as preferentially expressed in LD samples from JB and seven genes were found to be expressed more highly in HOL. The expression of six selected differentially expressed genes was confirmed by quantitative real-time PCR. The genes more highly expressed in JB are associated with unsaturated fatty acid synthesis, fat deposition, and the thyroid hormone pathway. These results are consistent with the increased amounts and proportions of monounsaturated fatty acids observed in the muscle of JB animals. By discovering as yet uncharacterized genes that are differentially regulated in this comparison, the work may lead us to a better understanding of the regulatory pathways involved in the development of intramuscular adipose tissue.
The importance of a high fat intake in the increasing prevalence of childhood and adult obesity remains controversial. Moreover, qualitative changes (i.e. the fatty acid composition of fats) have been largely disregarded. Herein is reviewed the role of polyunsaturated fatty acids (PUFAs) of the n-6 series in promoting adipogenesis in vitro and favouring adipose tissue development in rodents during the gestation/suckling period. Epidemiological data from infant studies as well as the assessment of the fatty acid composition of mature breast milk and infant formulas over the last decades in the Western industrialized world are revisited and appear consistent with animal data. Changes over decades in the intake of n-6 and n-3 PUFAs, with a striking increase in the linoleic acid/alpha-linolenic ratio, are observed. In adults, using a consumption model based upon production data, similar changes in the PUFA content of ingested lipids have been found for France, and are associated with an increase of fat consumption over the last 40 years. These profound quantitative and qualitative alterations can be traced in the food chain and shown to be due to changes in human dietary habits as well as in the feeding pattern of breeding stock. If prevention of obesity is a key issue for future generations, agricultural and food industry policies should be thoroughly reevaluated.
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