Double-muscled animals

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Double-muscled animals are of particular interest to meat producers because they are characterized by an exceptional muscular development and an increased carcass lean to fat ratio. The term is mainly restricted to cattle, but functional mutations in the myostatin gene causing this phenotype are also described in other species. The condition is associated with altered physiological and histological characteristics that bring about not only differences in meat quantity but also in animal performances and in meat quality. Therefore, the exploitation of double muscling has to be considered carefully. This article mainly focuses on observations in cattle.

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... Double-muscled animals have significantly higher slaughter yield (higher proportion of muscle tissue to connective tissue and fat), better formation of the carcass, and a higher proportion of individual culinary fragments. Furthermore, it is believed that higher proportion of brighter muscles determines higher tenderness of meat obtained from animals with hypertrophy (2,8). ...
... The content of intramuscular fat is affected by many factors (number and diameter of intramuscular adipocytes, ratio between uptake, synthesis, and degradation of triacylglycerols), but is negatively correlated with the protein content in beef meat (23). De Smet (8) suggested that in double-muscled animals, the IMF content is lower due to a decreased size of fat cells, not their decreasing number. There were insignificant differences in the amount of connective tissue between the studied crossbreeds, but the BB × HF was characterised by its slightly lower content. ...
... These results were in opposition to most of the data reported in the literature, showing that meat from double-muscled animals is lighter and has less pigmentation than that of normal-muscled animals (7,21,22). Some authors suggested that paler colour of meat from double-muscled animals is related to the higher proportion of white fibers in muscle tissue (8,9,21). This may be related to a different system of feeding or animal genotype (crossbred vs. pure-bred animals). ...
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The aim of the study was the evaluation of the effect of ageing on the extent of myofibrillar proteins degradation and tenderness of beef in different crossbreeds, BB × HF and SM × HF, from which the musculus semitendinosus was obtained. The pH value, basic composition of meat, and colour parameters were determined on the 3rd d post mortem. The Warner Bratzler shear force and the extent of protein degradation were evaluated in regard to the effect of ageing time. Meat of BB × HF crossbreed had a lower amount of intramuscular fat and higher protein content (P ≤ 0.05). The shear force decreased with ageing time in the case of both crossbreeds. However, the highest values were noted in SM × HF crossbreed on days 3 and 7 of ageing. The differences in proteolysis of myofibrillar proteins and polypeptides, determined by SDS-PAGE electrophoresis, were observed between crossbreeds and the ageing time. A significant decrease in desmin and increased levels of 49-46 kDa and 32-27 kDa polypeptides (products of proteolytic degradation) were observed with an increasing ageing time. In addition, the rate of increase in the amount of 32-27 kDa polypeptides was more significant in BB × HF crossbreed. The data obtained showed that tenderness and the extent of protein degradation are associated with ageing process and animals' genotype.
... Breeds as Belgian Blue and Piemontese have been shown to have more type IIB fibres and less type I fibres, which partly explains the overall increase in whiteness of meat from hypertrophied animals (Cullen et al., 1999). Thus, the double muscled animals have a higher proportion of fibres adapted for glycolytic metabolism (Boccard, 1981), which results in a faster rate of glycolysis and earlier post mortem rigor development, whereas ultimate pH values are generally not different from those of normal animals (De Smet, 2004). Concerning meat quality, the double muscled Piemontese compared with normal animals have higher water and protein content (Barge et al., 1993); the intramuscular fat content is usually about 1% or lower (Barge et al., 1993) and consequently the triacilglycerol content is greatly reduced, as a result of lower fat deposition, with a positive increase of the polyunsaturated/ saturated fatty acid ratio (Barge et al., 1993). ...
... Ngapo et al. (2002b) reported that the intramuscular collagen content in meat from double muscled animals was as much as 40% less than in normal animals. This fact is ascribed to the thinner network of perimysial connective tissue (De Smet, 2004). On the contrary, there is little difference in the nature of collagen crosslinks and collagen solubility in meat from double muscled and normal animals (Ngapo et al., 2002a;De Smet, 2004). ...
... This fact is ascribed to the thinner network of perimysial connective tissue (De Smet, 2004). On the contrary, there is little difference in the nature of collagen crosslinks and collagen solubility in meat from double muscled and normal animals (Ngapo et al., 2002a;De Smet, 2004). These findings are in agreement with earlier data of Destefanis et al. (1997), who observed no differences in collagen solubility in hypertrophied and normal animals of Piemontese breed. ...
The effect of the housing system on qualitative characteristics of longissimus thoracis et lumborum (LTL), semitendinosus (St) and supraspinatus (Ss) muscles was studied in cattle of hypertrophied Piemontese breed. Thirty young bulls, fifteen tie-stalled and fifteen housed in pens (5 m2/head of space allowance), were fed the same diet and were slaughtered at about 17 months of age and 560 kg live weight. Chemical analyses (pH24, chemical composition, haem iron and hydroxyproline contents, collagen heat solubility) and physical analyses (colour, water holding capacity, Warner Bratzler shear test) were performed on the three muscles, whilst sensory analysis was carried out on LTL muscle by a trained panel. Housing in pens increased hydroxyproline content and collagen solubility (P < 0.01), decreased lightness of the three muscles (P = 0.05) and influenced the other meat characteristics in a muscle-dependent manner. The loose housing system increased pH24 of LTL (P < 0.05), water content of LTL and St (P < 0.01), iron content of LTL and Ss (P < 0.05), redness and yellowness of Ss (P < 0.01), whilst decreasing protein content and yellowness of LTL and St (P < 0.01). No significant differences for organoleptic quality due to housing system were observed. On the whole, even if significant, the differences in chemical and physical properties of the meat due to housing system were limited. Therefore, in comparison with the tie-stall housing, the housing in pens might promote the ethical quality of the meat product, being more respectful of animal freedom of movement, without worsening the meat quality.
... The Belgian Blue beef breed is characterised by a very muscular carcass conformation due to the double muscling phenomenon and concomitantly a high yield of lean meat with distinct compositional and sensory properties compared to conventional beef breeds (De Smet, 2014). It represents a large share of total beef consumption in the Belgian market, which in recent years has witnessed an increased demand for dry-aged beef (Imazaki, Douny, Elansary, Scippo, & Clinquart, 2018). ...
The objective of this study was to evaluate the effect of aging period (0, 3, 6 or 9 weeks), aging temperature (2 versus 6 °C at 75% relative humidity, experiment 1) and relative humidity (70 versus 90% at 2 °C, experiment 2) on the sensory traits, oxidative stability and proteolysis of Belgian Blue beef. For each experiment, eight loins (M. longissimus thoracis et lumborum) from four animals (left and right side) were assigned to one of the two treatments (n = 4). Results showed no further tenderization after three weeks of aging, whereas metmyoglobin formation and lipid oxidation increased until nine weeks of aging (P < 0.05). During the nine weeks of aging, atypical flavor, odor and flavor intensity was affected (P < 0.05). This was accompanied by an increase of small peptides and other nitrogenous compounds. Aging temperature and relative humidity had only a very limited effect on the quality traits.
Few studies exist on homozygous myostatin gene mutant (MSTN‐/‐) pigs, especially on their reproductive ability. We have previously shown that semen quality of homozygous MSTN‐/‐ boars is comparable to that of wildtype (WT). However, no data exist on the reproductive ability of heterozygous MSTN gene mutant (MSTN+/‐) sows. The present study highlights showed that the heterozygous MSTN+/‐ sows have delayed pubertal age than WT sows (255.80 ± 6.79 vs 191.10 ± 3.42, respectively). The number of services per pregnancy of heterozygous MSTN+/‐ sows is significantly higher than that of WT sows (3.33 ± 0.43 vs 1.60 ± 0.25, respectively). Moreover, although heterozygous MSTN+/‐ sows have natural reproduction ability, their litter size was significantly lower than that of WT sows (7.75 ± 0.44 vs 14.25 ± 0.60, respectively). Offsprings generated from heterozygous MSTN+/‐ sow and homozygous MSTN‐/‐ boar were genotyped with the PCR and sequencing method to detect myostatin mutation and to identify whether the piglets are homozygous MSTN‐/‐ or heterozygous MSTN+/‐. The proportion of homozygous MSTN‐/‐ piglets was significantly lower than that of heterozygous MSTN+/‐ piglets (2.50 ± 0.35 vs 5.25 ± 0.60, respectively). Furthermore, none of the sows presented dystocia, and the phenotype of heterozygous MSTN+/‐ piglets was normal. However, 10% homozygous MSTN‐/‐ piglets died of dyspnoea within 2 hours after birth, 60% of homozygous MSTN‐/‐ piglets showed large tongues, and 50% had umbilical hernias. In summary, this study for the first time reports the reproduction traits of heterozygous MSTN+/‐ sows crossbred with homozygous MSTN‐/‐ boars. Paving the way in a new direction for the breeding and development of super lean meat varieties in the future.
Six normal-conformation and six double-muscled Belgian White-blue bulls were involved in a 2 × 2 × 2 factorial experiment to investigate the effect of genotype (normal versus double-muscled), body weight (400 versus 600 kg) and dietary crude protein (135 versus 165 g per kg dry matter) on voluntary feed intake, digestion and its consequences on the nutritive value, metabolites in blood and urine and nitrogen retention. The diet consisted of concentrate and maize silage (50:50, dry matter basis) and was fed ad libitum. Double-muscled bulls showed a significantly lower feed consumption (67.1 g DM per kg W0.75) compared to normal bulls (81.5 g). When adjusted for dry matter intake, digestibility was not affected by beef type. Some feed components tended to be better digested when body weight (crude fibre and nitrogen-free extractives) or dietary crude protein content (dry matter, organic matter, crude protein, nitrogen-free extractives and energy) were higher. Blood urea nitrogen was not dependent on genotype, but increased with body weight and dietary protein. Creatinine concentration in the blood and daily creatinine excretion in the urine were highest in double-muscled bulls and heavier animals. Urinary 3-methylhistidine excretion was not different between double-muscled and normal bulls, but increased with body weight. This was confirmed by the fact that nitrogen retention relative to intake was similar for both beef types and decreased with a higher body weight. A negative effect of stress on feed intake, muscle protein degradation and nitrogen retention in double-muscled bulls was not excluded.