Two experiments were carried out using 130 Friesian-type castrated males (steers) to compare pelleted dried grass with rolled barley as supplements to high quality grass silage for fattening steers. There were six treatments in each experiment and, in addition, Experiment 1 had a pre-experimental slaughter group. The animals on each treatment were group-fed grass silage ad libitum for 98 and 112 days in Experiments 1 and 2 respectively. The treatments were (1) no supplement, (2) 1·5 kg dried grass, (3) 3·0 kg dried grass, (4) 4·5 kg dried grass, (5) 1·5 kg barley and (6) 3·0 kg barley per head daily. Each increase in the level of supplement depressed silage DM intake but there was no difference between dried grass and rolled barley. At each level of supplementation, live-weight and carcass-weight gain for animals fed dried grass and barley were similar. Responses in terms of live weight and carcass weight to increasing increments of supplementary feed declined as the level of supplementation was increased.
Leydig cells produce testosterone in response to luteinizing hormone (LH) via the cyclic adenosine monophosphate (cAMP)/protein kinase A pathway. Additionally, these cells are responsible for producing insulin-like peptide 3 (INSL3), a peptide hormone that is essential for testicular descent. The insl3 promoterin Leydig cells can be activated by cAMP through the transcription factor Nur77. While the mechanism of LH action on testosterone production is well characterized, the effect of LH on insl3 abundance has yet to be shown directly. MA-10 Leydig cells were treated with either 0 and 100 ng/mL LH for 3 and 6 hours in a 2x2 factorial design or 0 and 0.6 mM cAMP for 6 hours. Relative insl3 mRNA abundance was determined byquantitative reverse transcription PCR. While cAMP treatment failed to alter abundance of insl3 mRNA, treatment with 100ng/mL LH for 3 hours induced a significant increase in insl3 mRNA abundance. These data indicate that LH does increase insl3 mRNA abundance in MA-10 cells.
Classification of pig carcasses in the European Community is based on the lean meat percentage of the carcass. The lean meat percentage is predicted from instrumental carcass measurements, such as fat and muscle depth measurements, obtained in the slaughter-line. The prediction formula employed is derived from the data of a dissection experiment and has to meet requirements for authorization as put down in EC regulations. Requirements involve the sampling procedure and sample size for the dissected carcasses and the accuracy of prediction. Formulae are often derived by linear regression. In this paper we look at a particular type of sampling scheme. This involves selection of carcasses on the basis of carcass measurements not all of which are intended to be used as prediction variables. This sampling scheme frequently appears in requests for authorization of carcass measurement instruments and accompanying prediction formulae, despite the fact that it lacks formal statistical justification when used in conjunction with linear regression. The objective of this work was to assess the performance of the prediction formula that follows from this potentially faulty combination of sampling scheme and linear regression in relation to the requirements in the EC regulations. We show that this sampling scheme may produce poor predictions for lean meat percentage compared with proper sampling procedures with selection on prediction variables only or random sampling. We do so by computer simulation. Initially, simulated data were based on recent and historic data from The Netherlands. Prediction variables are fat and muscle depth measurements. The additional variable involved in sampling, but not included in the regression, was carcass weight. We also show that due to this faulty sampling scheme there is a serious risk that a new measurement instrument may not be authorized because performance criteria in the EC-regulations are not met.
Classification of pig carcasses in the European Community (EC) is based on the lean meat percentage of the carcasses. The lean meat percentage is predicted from instrumental carcass measurements, such as fat and muscle depth measurements, obtained in the slaughterline. The prediction formula for an instrument is derived from the data of a dissection experiment. When the relationship between percentage lean and instrumental carcass measurements differs between subpopulations, such as sexes or breeds, accuracy of prediction may differ between these subpopulations. In particular for some subpopulations predicted lean meat percentages may be systematically too low and for other subpopulations systematically too high. Producers or buyers that largely specialize in subpopulations where the percentage lean is underestimated, are put at a financial disadvantage.
The aim of this paper is to gain insight, on the basis of real data, into the effects of differences between subpopulations on the accuracy of the predicted percentage lean meat of pig carcasses. A simulation study was performed based on data from dissection trials in The Netherlands, comprising gilts and castrated males, and trials in Spain, comprising different genetic types. The possible gain in accuracy, i.e. reduction of prediction bias and mean squared prediction error, by the use of separate prediction formulae for (some of) the subpopulations was determined.
We concluded that marked bias in the predicted percentage lean meat may occur between subpopulations when a single overall prediction formula is employed. Systematic differences in predicted percentage lean between subpopulations that are overestimated and underestimated may exceed 4% and for selected values of instrumental measurements may run up to 6%. Bias between subpopulations may be eliminated, and prediction accuracy may be markedly improved, when separate prediction formulae are used. With the use of separate formulae the root mean squared prediction error may be reduced by 13 to 26% of the expected value when a single prediction formula is used for all pig carcasses.
These are substantial reductions on a national scale. This suggests that there will be a commercial interest in the use of separate prediction formulae for different subpopulations. In the near future, when the use of implants becomes more reliable, subpopulations will be recognized automatically in the slaughterline and use of different prediction formulae will become practically feasible. Some possible consequences for the EC regulations and national safeguards for quality of prediction formulae are discussed.
Non-polar lipids (NPL) accumulate within the mammary epithelial cell during lactation; however there are no reported systematic studies that utilize NPL composition as a sign of differentiation. Additionally, there are no reported systematic studies on the response of a bovine mammary alveolar cell line (MAC-T), to a range of lactogenic hormone concentrations, or different lipogenic substrates. In a 3 x 3 factorial arrangement, the effect of growth hormone (GH; 0, 10, 100 ng/ml), and prolactin (PRL; 0, 5, 10 µg/ml) on the lipid composition of MAC-T was examined using thin layer chromatography. Using the optimal hormone treatment (10 ng/ml GH, 5 µg/ml PRL) for NPL synthesis, inclusion of 10 mM sodium acetate (NaOAc) was assessed to determine the effect of lipogenic substrate on lipid composition. GH had a significant effect on NPL, cholesterol, phosphatidylcholine, phosphatidylinostitol, and sphingomyelin (SM), while PRL only affected SM. NaOAc had a significant effect on NPL, phosphatidylethanolamine and SM. The proportion of NPL peaked with 10 ng/ml GH, but dropped to near-control levels with 100 ng/ml GH. This study underscores the importance of testing a range of hormone concentrations when assessing lipogenic profile of MAC-T cells.
The influence of a diet of either pasture or hay on the development of lactic acidosis in sheep was investigated using a grain challenge approach. Twenty-four Merino wethers with a mean live weight of 36·7 (s.e.3·6) kg were used; 12 were adapted to grass pasture and 12 to hay (lucerne and oaten hay, 60: 40) for 4 weeks before being given 1 kg of crushed barley via stomach tube. Six sheep in each group were also given virginiamycin (VM; 50 mg/kg barley) with the grain to test the efficacy of this antibiotic in controlling the bacteria responsible for the development of acidosis. Changes in volatile fatty acid (VFA), pH, lactate and bacterial count in the rumen and faecal pH and dry matter (DM) were measured for a 24-h period following administration of the barley. Daily intakes of hay were measured for a 10-day period following grain engorgement. Total ruminal VFA increased ( P < 0·01) over time and tended ( P = 0·08) to be higher in sheep adapted to hay than in those adapted to pasture (67·5 v. 59·8 mmol/l). The molar proportions of VFA changed ( P < 0·01) over time in favour of propionate in both groups. Ruminal pH was higher ( P < 0·001) in pasture-adapted sheep, but declined ( P < 0·001) in both groups over time following the introduction of barley. This decline in pH was associated with increases in ruminal concentration of VFA in pasture-adapted sheep and VFA and lactate in hay-adapted sheep. The addition of VM resulted in a higher ( P < 0·001) proportion of propionate and a trend towards higher ( P = 0·24) faecal pH and DM content. Faecal pH and DM content declined ( P < 0·001) over time and was lower for the pasture-adapted sheep. The introduction of either barley alone or barley with VM from both hay and pasture diets increased ( P < 0·05) the viable counts of total bacteria, Streptococcus bovis and lactic acid bacteria. Bacterial isolates were purified and identified by complete sequencing of the 16S rRNA gene to determine the predominant bacteria during the overfeeding of grain. Isolates from medium selective for S. bovis were all identified as this species when VM was not given. VM had no effect on counts of viable bacteria, but inhibited the growth of S. bovis .
This study has shown that sheep given hay are more susceptible to lactic acidosis, the signs of which can be reduced by VM.
Carbohydrate response element (ChRE) binding protein (ChREBP) is a transcription factor that is regulated by intracellular glucose levels and activates several lipogenic genes including acetyl CoA carboxylase (ACC). Previous studies of the ChREBP system have used both in vivo models as well as isolated primary hepatocytes. Due to the difficulties in isolation and genetic variability of primary cell culture, we propose the use of a normal murine liver cell line (NMuLi) as a convenient alternative to primary isolated hepatocytes. We show that high (25 mM) but not low (0.5 or 5 mM) glucose activates a luciferase reporter driven by 4 repeated ChREs, as well as the murine ACC promoter segment from –220 to +21. Furthermore, using small interfering RNA to knock-down ChREBP, we show that ChREBP is required for this glucose-induced luciferase reporter activation. Finally, using chromatin immunoprecipitation we show that ChREBP directly binds to the ChRE within the promoter region of the ACC gene in the presence of high but not low glucose. Together, these results suggest that NMuLi cells may be used as an alternative to primary isolated hepatocytes for studies of the ChREBP system.
Depressed hog prices in 1998 and 1999 were due to not enough shackle space (kill capacity) and not to a glut of slaughter swine. However, many swine producers were put out of business in California. In 2000, market prices rebounded due to increased shackle space and reduced numbers of slaughter swine available as a result of the sellouts of the previous two years. The economic roller coaster ride emphasized the need for maximizing profit while streamlining operations. Increasing numbers of pigs per litter, and thereby reducing the cost per pig produced, is one aspect of streamlining. A significant step in improved litter efficiency would be to utilize platelet activating factor (PAF) in commercial swine operations. Platelet activating factor is involved in signal transduction within many of the body’s physiological systems. Of primary interest in the reproductive system is PAF’s enhancement of embryonic development, placental attachment and sperm functioning. The amount of embryo-derived PAF produced is correlated to pregnancy potential, since higher PAF levels lead to greater numbers of embryos developing to the blastocyst stage. It is produced by the embryos of various mammalian species, exerts significant effects upon the preimplantation embryo placental attachment, and perhaps maternal recognition of pregnancy and sperm functioning. Presently, only Professor John Diehl of the Animal and Veterinary Science Department at Clemson University, in collaboration with others, has published data to suggest that PAF is found in either male or female swine reproductive tracts. Most notably, PAF was found in the uterine luminal fluid (ULF), the developing filamentous embryo and the endometrium.
An experiment was performed to assess the metabolic adaptation and hormonal regulation in young female rabbits during long-term food restriction and subsequent compensatory growth during rearing. Feeding level was either ad libitum (AL, no. = 52) or restricted (R, no. = 52). From 6 to 12 weeks of age, food intake ofR was kept at a constant level. This resulted in an increase in relative restriction as compared with AL to 0-54of AL intake at 12 weeks of age (restriction period). Thereafter food intake gradually increased to 0-95 of AL at 17 weeks of age (recovery period). During the last 5 days before insemination at 17-5 weeks of age, all animals were fed to appetite. Blood samples were taken weekly from 6 to 17 weeks of age from 11 animals in each group. Growth rate of R was reduced during the restricted period (29 (s.d. 2) v. 44 (s.d. 5) g/day for R and AL, respectively; P 0-05), but was higher in the recovery period (30 (s.d. 3) v. 27 (s.d. 4) g/day, respectively; P
Mesenchymal stem cells (MSC) have been isolated from equine tissues, most notably adipose and bonemarrow. On the basis of ability for self-renewal, molecular marker expression and differentiation potential, we characterized MSCs isolated from a tissue not yet explored in the equine. After isolation, MSCs weremaintained in culture for 25 passages before senescence was observed. Reverse transcription-PCR revealedembryonic transcription factor Oct4 mRNA, as well as mRNA for fucosyltransferase 4 and ST3B-galactosid α 2,3 sialySSEA4, respylxanthine l ltransferase 2, two enzymes responsible for synthesis of embryonic surface markersSSEA1 and ectively. Treatment with insulin, dexamethasone, indomethacin andisobutylmethed to increased oil red O staining (P<0.05) indicating successful adipogenicdifferentiation. These data indicate the stem-like nature of these cells and their successful isolation from this tissue source. However, further characterization is needed to determine their full potential.
An in vivo experiment was conducted to examine changes in fermentation end-products in the gastro-intestinal tract (GIT) of weaning piglets by the inclusion of fermentable carbohydrates in the diet. The experiment was repeated in three replicates of 36 piglets. Piglets were raised free of antibiotics and creep feeding prior to weaning at 4 weeks of age. Each replicate was conducted over a period of 10 days. The piglets were offered one of two dietary treatments: control diet (CON), and fermentable carbohydrate enriched diet (CHO); and were subjected to one of the two fasting treatments (i) fasting for 2 days in the beginning of the experimental period and (ii) non-fasting. Piglets were slaughtered on the 1st, 4th and 10th day of each period. Digesta samples were collected from: first half of small intestine, second half of small intestine, caecum, and colon. The dry matter, volatile fatty acid (VFA) profile, and ammonia concentrations were analysed. Food intake, growth and food conversion ratio were also recorded. There were no differences in production performances such as growth and food conversion ratio (FCR) between the treatment groups. Concentrations of VFA were significantly higher, while ammonia concentration was significantly lower in the CHO group compared to the CON group in different fermentation sites within the GIT (P<0·001), and on different slaughtering days (P<0·05). Fasting had no effect on fermentation end-products. This study concludes that the addition of fermentable carbohydrates of varying fermentabilities stimulated carbohydrate fermentation, with reduction in protein fermentation along the different parts of GIT studied, in weaning piglets
Sixty-four Azawak male weaned calves were allotted to eight treatments (T) in two trials to study the effect of timing (day or day-and-night) and duration of grazing on diet selection, faecal output, eating time, forage intake and weight changes. Grazing time during the day was 6 h for T 1, 2 and 3; 9 h for T 4, 5 and 6; and 12 h for T 7 and 8. Night grazing time was 0 h for T 1, 4 and 7; 3 h for T 2, 5 and 8; and 6 h for T 3 and 6. The trials were conducted from July 1995 to May 1996 covering the wet (WS), early dry (EDS) and late dry (LDS) seasons. Eight oesophageally fistulated steers were used in a cross-over design to sample the diet selected by day-grazers (D1) and by day-and-night-grazers during the day (D2) and at night (N2). Forage intake was determined from individual data on faecal output from all the calves and means of in vitro organic matter digestibility of extrusa of the fistulated steers. Water intake and eating time were measured in LDS. In WS there were no differences (P > 0?05) in the quality of the diet (extrusa) selected for D1, D2 and N2. In LDS, crude protein content for D1 was lower than for D2 (73 v. 79 (s.e. 2) g/kg dry matter, P < 0?05). In all seasons, faecal output and forage intake increased with total duration of grazing. Total time spent eating increased linearly with increasing total time allowed for grazing. These results suggest that allowing additional grazing time during the night leads to increased forage intake and consequently provides an opportunity for better animal production, especially in the dry season
The Dutch scrapie eradication program aims at the exclusive use of homozygous ARR/ARR breeding rams by the end of 2004. As a consequence, breeds with a small population size and a low frequency of the ARR allele may suffer unacceptable losses of genetic diversity and high inbreeding levels. We simulated three breeding strategies to assess their efficacy in eliminating scrapie sensitive alleles and their effect on inbreeding levels. Under mild selection, both homozygous and heterozygous ARR rams were used indiscriminately. Under moderate selection, homozygous ARR rams were used preferably but they were supplemented with heterozygous rams when necessary. Under severe selection, only homozygous rams were used. Severe selection mimics then the proposed eradication program. Simulations were carried out with allelic frequencies and population parameters of existent rare breeds in The Netherlands. With severe selection all simulated breeds showed unacceptably high inbreeding rates (> 0•5% per year). For some breeds, moderate selection resulted in acceptable inbreeding rates, while for other breeds only mild selection resulted in acceptable rates. The frequency of the ARR allele after 5 years of selection was only slightly lower with moderate selection than with severe selection (0•8% lower on average), but it was clearly lower with mild selection. Based on these simulations, we propose a selection program where with low frequencies of the ARR allele, mild selection is used initially. Once the ARR frequencies rise to a particular value, the switch can be made to moderate selection. The population size (e.g. below 750, 750 to 3750 and above 3750 ewes) determines the frequency of the ARR allele at which the switch can be made (33%, 25% and 10%, respectively). With even higher ARR frequencies (above 70%, 50% and 33%, respectively) the regime can be changed to severe selection.
In the accompanying paper, specific genetic factors for body weight and food intake were identified in nonreproductive male and female mice of a line selected for high litter size at birth (average of 22 born per litter) and a non-selected control line (average of 10 born per litter). The existence of these factors are indicated by variation in efficiency parameters such as growth efficiency and maintenance requirements. Residual food intake (RFI) and Parks' estimates of growth efficiency (AB) and maintenance requirements (MEm) were used to quantify these factors. In the growing period, females had a higher RFI (are less efficient) than males. At maturity, selected mice had higher RFI than control mice and selected females had higher RFI than selected males. AB was higher in selected-line mice than in control-line mice, and higher in males than infernales. MEm was higher in selected-line mice than in control-line mice, and higher in females than in males. The results indicate the existence of specific genetic factors for both growth efficiency and maintenance requirements. Selected females may increase RFI in the adult state to anticipate the metabolically stressful periods of pregnancy and lactation, to support a genetically highly increased litter size.
Differences in the metabolic resource situation between non-reproductive male and female mice of a line selected for high litter size at birth (average of 22 born per litter) and a non-selected control line (average of W born per litter) were investigated in two replicates. Brody curves were fitted to individual data on body weight against age and linear regression lines were fitted to individual data on cumulative food intake against age. Mature body weight and mature daily food intake were higher in selected mice than in control mice and higher in males than in females. Selected males matured faster than selected females and control mice. In general, differences in growth and food intake curves between species or lines can mostly be explained by differences in mature size. Therefore, parameters were subsequently scaled by individual estimates of mature body weight. Differences that remain after scaling are a consequence of what have been called specific genetic factors. Scaled mature food intake was higher in selected mice than in control mice and higher in females than in males. Scaled maturation rate was higher in selected mice than in control mice and higher in selected males than in selected females. This shows that in the present study, specific genetic factors have been detected for both body weight and food intake, which suggests that selection for increased litter size has disproportionally changed the resource allocation pattern.
Growth Hormone (GH) improves growth and lactation in many species. Mammary epithelium is responsive to GH though the mechanism of these effects has not yet been fully characterized. Bovine Mammary Alveolar Cell-T (MAC-T) cells uniformly differentiate and secrete casein proteins in response to dexamethasone, insulin and prolactin (DIP) and are a widely used ruminant mammary cell model. We have found significant changes in triacyglycerol, cholesterol and phospholipid distribution in MAC -T cells stimulated with 10 ng/ml GH. To characterize these direct effects of GH on a proteomic level, total protein was isolated from MAC-T cells after differentiation for seven days with DIP and either 0 or 10 ng/ml GH. Proteins were separated by isoelectric point and molecular weight using two-dimensional gel electrophoresis. We have observed a change in the abundance of multiple proteins when MAC-T cells are stimulated with GH and the identification of these proteins is being pursued using MALDI-TOF mass spectrometry.
An experiment was conducted to investigate the effect of dietary fermentable fibre on the pH and ammonia emission from slurry of growing-finishing pigs. Commercial crossbred barrows with initial body weight of 45 kg were used. Pigs were housed in two climate chambers. Twelve groups of 14 barrows were assigned to one of four diets. The diets differed in the content of fermentable fibre by adjusting the amount of sugar-beet pulp silage (SBPS). The control diet contained no SBPS. In the other three diets tapioca was replaced with three levels (50, 100 and 150 g/kg dry matter (DM)) of SBPS. After a 13-day adaptation period, the slurry was collected in a slurry channel for 7 days. A sample of this slurry was placed in a laboratory system to measure the pH and ammonia emission for a period of 7 days.
The total volatile fatty acid (VTA) and DM concentration of the slurry increased as tapioca was replaced by SBPS. The ammonium concentration was not influenced by SBPS. For each 50 g/kg increase of SBPS, the pH of the slurry decreased by 0·45 units and ammonia emission decreased approximately by 0·15.
It is concluded that increasing the level of fermentable fibre in the diet of growing-finishing pigs increases slurry VFA concentration. This consequently decreases the pH and ammonia emission from the slurry.
The objective of this study was to compare two methods for analysis of longevity in dairy cattle. The first method, currently used for routine genetic evaluation in the UK, uses a linear model to analyse lifespan, i.e. the number of lactations a cow has survived or is expected to survive. The second method was based on the concept of proportional hazard, i.e. modelling the conditional survival probability of a cow as a function of time. Comparisons were-based on estimated heritabilities, ranking of estimated breeding values of sires, estimated effects of covariates used in the final models, and the distribution of residuals. The same data set, 21497 observations on the number of lactations cows had survived, was used for both analyses, even in the presence of censored observations. Cows in the data were progeny of 487 sires. Heritability estimates for lifespan or survival were approximately 0-06 for both methods, using the definition of heritability on a logarithmic scale for the proportional hazards model. Correlations between breeding values for sires were high, with absolute values ranging from 0-93 to 0-98, depending on the model fitted. It was concluded that it may be justified to use the standard Weibull model even for discrete time measures such as the number of completed lactations, but that more research is needed in the area of discrete time variates.
Survival data were simulated under the Weibull model in a half-sib family design, and about 50% of the records were censored. The data were analysed using the proportional hazard model (PHM) and, after transformation to survival scores, using a linear and a binary (logit) model (LIN and BIN, respectively), where the survival scores are indicators of survival during time period t given survival up to period t-1. Correlations between estimated and true breeding values of sires (accuracies of selection) were very similar for all three models (differences were smaller than 0•3%). Daughter effects were however less accurately predicted by the LIN model, i.e. taking proper account of the distribution of the survival data yields more accurate predictions of daughter effects. The estimated variance components and regressions of true on estimated breeding values were difficult to compare for the LIN models, because estimated breeding values were expressed as additive effects on survival scores while the simulated true breeding values were expressed on the underlying scale. Also the differences in accuracy of selection between sire and animal model breeding value estimates were small, probably due to the half-sib family design of the data. To estimate breeding values for functional survival, i.e. the component of survival that is genetically independent of production (here milk yield), two methods were compared: (i) breeding values were predicted by a single-trait linear model with a phenotypic regression on milk yield; and (ii) breeding values were predicted by a two-trait linear model for survival and milk yield, and breeding values for survival corrected for milk yield were obtained by a genetic regression on the milk yield breeding value estimates. Both methods yielded very similar accuracies of selection for functional survival, and are expected to be equivalent.
According to animal breeding theory, profit after, say, 10 generations of selection is maximized when the usually non-linear profit function is approximated by a linear breeding goal where the linearization is at the population mean in generation 10 and the linear breeding goal is subsequently predicted by a linear index for which the animals are selected. The prediction of the population mean at generation 10 requires linear relationships among the traits that constitute the non-linear profit, because otherwise this prediction becomes very complicated.
A non-linear index is proposed that simply estimates the non-linear goal H =f(u) by Ĥ =f(û), where u = vector of genetic values for the traits and u is its (BLUP) estimate. This non-linear index does not require predictions of (future) population means and does not require linearly related traits.
To test these indices a simple meat production example was constructed where the non-linearity between the traits was due to the competition between weight and probability of survival for the same resources from food intake. In the model selection for weight and, in particular, for weight over costs (mainly food) led to reduced profits due to large reductions of survival rates. Although, the example was oversimplified, this should provide a warning for the use of oversimplified breeding goals, e.g. fitness traits may reduce by more than expected from base population genetic parameters.
When probability of survival and weight were measured, a non-linear index of these non-linear traits gave the greatest genetic gains. Failure to update genetic parameters each generation severely reduced genetic gain and, if linear indices were used, it was also important to update the economic weights. When probability of survival was measured, profit could be calculated on each animal and included as a trait in the calculation of estimated breeding value. This yielded high genetic gain and did not require updating of genetic parameters or economic weights.
An increased sodium appetite has been demonstrated in cattle following supplementation with sodium in the neonatal period, but it is unclear whether the sodium appetite of calves can be influenced in utero by the dam's sodium intake during pregnancy. Twenty-two non-lactating, pregnant dairy cows received either a diet of silage and concentrates or the same diet with 70 g NaCl per day added to it for the last 2 months of pregnancy. The sodium supplement increased the birth weight of their calves but after 6 weeks there was no difference between treatments in calf weight. In addition to milk, calves in both treatments were offered a choice of concentrates with normal or high sodium concentrations (5.8 and 10.8 g/kg dry matter, respectively). Calves from the cows that had received supplementary sodium during pregnancy ate more of the high sodium concentrate than calves from cows without the sodium supplement, demonstrating that sodium appetite could be entrained by the sodium intake of the dam during late pregnancy.
Sheep farming in the UK is characterized by a crossbreeding system where ‘Longwool’ sire breeds are mated with hill dam breeds, with the crossbred (F1) ewe lambs retained for mating to terminal sires. The F1 wether and terminal-sire cross lambs are marketed for meat. At selection, F1 females are typically assessed visually for type traits relevant to dam lines, and these traits could be considered as goal traits. Their offspring and their male sibs derive their value from carcass traits. This study investigated the genetic relationships between type (subjective) and carcass (objective) traits in F1 lambs, and their potential impact on genetic improvement within this production system. Bluefaced Leicester rams were crossed with Scottish Blackface and Hardy Speckled Face ewes to produce F1 (‘Mule’) lambs. The wether lambs (no. = 2197) were selected for slaughter at a target condition (a carcass fat score of 2/3L) and a number of live and carcass traits were measured. Carcass dissection data were collected on approximately one-third of these wether lambs. The ewe lambs (no. = 2423) were measured for similar live traits but at a fixed age (195 5.5 days). In addition, they were subjectively assessed for a number of functional and type traits. Genetic parameters among these traits were then estimated. Heritabilities for the ewe traits were generally moderate (0.18 to 0.31) and genetic correlations between the traits were variable, with some moderate to high correlations (favourable in direction) of growth/carcass traits with overall type traits. Live weight at slaughter in wethers was highly correlated to live weight at constant age in ewes (r=0.72). In the wethers, live, cold carcass and lean weight had moderately high heritabilities (between 0.26 and 0.46), and were positively correlated with slaughter age (≥0.79). However, age at slaughter in wethers was highly negatively correlated with growth/carcass and overall type traits in ewes (between -0.45 and -0.97), perhaps reflecting differences in maturity in lambs measured at a target fatness versus age. The correlations of most other type traits in ewes with wether traits were non-significant. These results show that the subjectively assessed type traits (at least as measured in this study) will not deteriorate, and some will in fact be improved, in a selection programme aiming to improve carcass merit. DEFRA / MLC
Individual food intake characteristics and indicators of gut physiology of group-housed weanling pigs were measured in relation to pre-weaning consumption of creep food. Additionally, the effects of creep food consumption on pre-weaning body weight and gain were assessed. A total of 48 litters was used in two trials. From 11 days of age until weaning (day 28), all 48 litters were given a creep food (12.7 MJ net energy (NE) per kg, 15.2 g lysine per kg) supplemented with 10 g chromium III oxide per kg. Piglets showing green-coloured faeces on three sampling days were designated as good eaters, whereas piglets that never showed green faeces were labelled as non-eaters. Piglets having green faeces once or twice were designated as moderate eaters. Based on availability, body weight, litter origin, genotype and gender 29 good eaters, 32 moderate eaters and 29 non-eaters were selected in the first trial. In the second trial there were 30 good eaters, 33 moderate eaters, and 27 non-eaters. In each trial eight piglets of each creep-food eating type were immediately killed to serve as a reference group. The remaining piglets of each eating type were weaned and placed in pens equipped with computerized feeding stations so that distributions of body weight, litter origin, and gender were similar within pens. In each trial, eight pigs of each eating type were killed 5 days after weaning in order to determine villous heights and crypt depths in the proximal small intestine and volatile fatty acid (VFA) concentrations in the colon. While being suckled, body weight was not related to the pre-weaning consumption of creep food (P > 0.1) whereas average daily gain of the good eaters during the creep feeding period was higher (P < 0.05) than that of the moderate and non-eaters. Both morphology measures and VFA concentrations on the day of weaning were unaffected (P > 0.1) by the pre-weaning food consumption. After weaning, food intake and gain of the total group of good eaters were higher (P < 0.05) than that of the non-eaters, whereas villous height and villous height : crypt depth ratios did not differ (P > 0.1). Neither total VFA concentration nor the proportion of branched-chain VFA were affected by creep food consumption while being suckled. Total VFA concentration in the colon was positively associated with body-weight gain (P < 0.001). This study confirms earlier findings that consumption of creep food while being suckled stimulates food intake and growth after weaning. However, the beneficial effects were not associated with a prevention of damage to morphology of the small intestine.
This rangeland condition assessment was conducted as part of the Cal Poly Rangeland Condition Assessment Project. Five pastures comprising 31.7 acres at the Cal Poly sheep unit were assessed to collect baseline ecological information. Methods used were Line-point Intercept, Belt Transect, Residual Dry Matter, and the rangeland health indicators recommended by Pyke et al., 2002. Additionally, a preliminary species list was collected. The rangeland health assessment method found all pastures to have no to slight departure from the local reference area when evaluated for soil and site stability, hydrologic function, and biotic integrity.
The aims of this study were to examine population structure and inbreeding trend in six dog breeds in Finland and to assess the inbreeding depression for hip and elbow dysplasia. Data consisted of 289 569 dogs, of which 36 924 dogs also had a record for hip and/or elbow dysplasia screening. From the early 1980s onwards, inbreeding trends were decreasing in the Golden Retriever, the Labrador Retriever, the Rough Collie and the Rottweiler, probably as a result of importations of dogs, and somewhat increasing in the Finnish Hound and the German Shepherd. When analysed per generation, observed mean inbreeding coefficients were higher than the expected ones in each breed, indicating that breeders have not actively avoided inbreeding. As a class effect, the inbreeding level was significant only for hip dysplasia in the Labrador Retriever and the German Shepherd breeds. As a regression, inbreeding level of a dog had only a minor effect on both of the dysplasias. Hip dysplasia in the Labrador Retriever appeared to be more influenced by longer term aggregation of homozygosity (long-term inbreeding) in animals than by shorter-term inbreeding. When analysed from two data sets with a minimum of five and two ancestral generations for each dog in the data, a statistically significant association between hip dysplasia and inbreeding for the Labrador Retriever could be detected only in the former data set.
This study was undertaken to quantify the effect of episodes of subclinical hypocalcaemia on the interval from calving to first ovulation. It incorporated three separate surveys during early lactation of 44 and 60 cows at Mutdapilly Research Stationand 56 cows at Wollongbar Agricultural Institute. Twenty-five, 37 and 39% of cows respectively, experienced episodes later than 3 days after calving, of non-parturient post-partum hypocalcaemia, when plasma calcium concentration fell below 2.00 mmol/l. Episodes of subclinical hypocalcaemia did not affect the interval to first post-partum ovulation in the two experiments conducted at Mutdapilly Research Station but ovulation was significantly delayed in cows that experienced episodes of subclinical hypocalcaemia at Wollongbar Agricultural Institute.
A total of 198, 27-day-old weanling gilts (7.7 kg) were used to study the associations between food intake characteristics measured in individual pigs but which were group-housed, and indicators of gut physiology at 5 days after weaning. All piglets were offered ad libitum access to food and water and were housed in pens (11 piglets per pen) equipped with feeding stations in order to determine the time between weaning and the start of the first food intake (latency time; h), and the increase in daily food intake (daily increase; g/kg0.75 per day) for each individual. Forty piglets were selected that either had an early (≤2 h) or a late (≥23 h) start of food intake and subsequently either had a relatively fast (≥18 g/kg0.75 per day) or slow (≤2 g/kg0.75 per day) increase in daily food intake so that there were four different groups. Five days after weaning, the 40 piglets were killed in order to determine histological (villous height, crypt depth, number of goblet cells) and functional (maltase and sucrase activities) measures in the proximal small intestine (SI), and microbial measures (ammonia and volatile fatty acid (VFA) concentrations) and dry-matter (DM) content in the distal SI, caecum and colon. Thirteen unweaned piglets were killed to serve as the reference group. Villous height/crypt depth ratio (P < 0.05), number (P < 0.01) of goblet cells on the villi and crypts, and sucrase activity (P < 0.001) in the proximal SI of the unweaned piglets were higher than in the weaned piglets. The proportion of branched-chain VFA (bcVFA; P < 0.01), ammonia-nitrogen (P < 0.001) and DM concentrations (P < 0.01) in the contents of the caecum as well as proportions of bcVFA in the contents of the colon of the unweaned piglets were higher than in the weaned piglets. Apart from a tendency towards an interaction (P < 0.1) between latency time and daily increase with regard to villous height/crypt depth ratio and number of goblet cells on the villi of the proximal SI, histology and function of the proximal SI and digesta characteristics of the distal SI, caecum and colon were not affected by latency time. Piglets with a fast increase in food intake tended to have longer villi on the proximal SI (P < 0.1), and had less acid-mucin containing goblet cells (P < 0.05) on these villi than had the piglets with a slow increase. The piglets with a fast increase had a higher DM content in the colon and tended to have a higher total VFA-concentration in the caecum than did their counterparts with a slow increase. The genotype of the piglets affected maltase (P < 0.01) and sucrase (P < 0.05) activities in the proximal SI and tended to affect the villous height/crypt depth ratio (P < 0.06). Genotype also affected total VFA concentrations (P < 0.05) and tended to affect the ammonia nitrogen (P < 0.1) in the colon and caecum, respectively. This study indicates that within the range of practical food intake levels recorded, the physiology and function of the gut is not markedly affected by the time between weaning and the onset of feeding or by the subsequent increase in daily food intake.
Genetic associations were estimated between pathogen-specific cases of clinical mastitis (CM), lactational average somatic cell score (LACSCS), and patterns of peaks in somatic cell count (SCC) which were based on deviations from the typical lactation curve for SCC. The dataset contained test-day records on SCC in 94 781 lactations of 25416 cows of different parities. Out of these 94 781 lactations, 41 828 lactations had recordings on occurrence of pathogen-specific CM and on SCC, and 52 953 lactations had recordings on SCC only. A total of 5 324 lactations with cases of CM were recorded. Analysed pathogens were Staphylococcus aureus, coagulase negative staphylococci, Escherichia coli, Streptococcus dysgalactiae, Streptococcus uberis, and culture-negative samples. Pattern definitions were based on three or five consecutive test-day recordings of SCC. They differentiated between short or longer periods of increased SCC, and also between lactations with and without recovery. Occurrence of pathogen-specific CM and presence of patterns of peaks in SCC were both scored as binary traits. Variance components for sire, maternal grandsire, and permanent animal effects were estimated using AS-REML. The estimated heritability for overall CM was 0.04, and similar heritabilities for pathogen-specific CM were estimated. Heritabilities for the patterns of peaks in SCC ranged from 0.01 to 0.06. Heritabilities for LACSCS were 0.07 to 0.08. Genetic correlations with patterns of peaks in SCC differed for each pathogen. Generally, genetic correlations between pathogen-specific CM and patterns of peaks in SCC were stronger than the correlations with LACSCS. This suggests that genetic selection purely on diminishing presence of peaks in SCC would decrease the incidence of pathogen-specific CM more effectively than selecting purely on lower LACSCS
Fertility data collected on 17131 Holstein-Friesian cows from 158 dairy herds in Australia were used to estimate heritabilities for and correlations among several fertility traits using a sire model. Pregnancy rate (PR), survival (Surv), calving interval (CI), calving to first service interval (CFS), insemination rate (coded as 1 if a cow received a service or 0 otherwise) (InsemR) and first service non-return rate (FNRR) were the main traits analysed in a six-trait model. Among the traits, CFS had the highest h(2) (0.13) and FNRR had the lowest h(2) (0.01). Genetic correlations among the traits were higher than environmental correlations in all cases. The genetic correlations of PR with InsemR, FNRR, CFS, CI and Surv were 0.74, 0.79 and -0.84, -0.57, and 0.67, respectively. The genetic correlation between InsemR and CFS was high (-0.95) indicating that they almost measure the same trait. Analysis of data from cows that did not return to service after the first service despite not being pregnant (so-called 'phantom' cow syndrome) showed that the syndrome is not heritable. The relatively high genetic correlation of PR with traits such as CI and Surv that can be extracted from milk recording data and CFS, FNRR and InsemR that can be obtained from mating data suggests that routine genetic evaluation of sires for daughter fertility based on these traits can be implemented in national selection programs.
Castrated and entire Boer bucks (no.=60) in groups of between three and five animals were slaughtered at 5, 15, 30, 45, 60, 75, 90 and 105 kg live weight (5- and 15-kg animals were not castrated). Ultimate pH, muscle colour (subjective and objective measurement), subcutaneous fat colour, total pigment concentration, shear force values and eating quality were investigated. The ultimate pH of longissimus muscle increased from 5.7 to 6.2 (P<0.05) as animals were slaughtered at heavier weights. Slaughter weight had an influence on chromameter muscle colour (L*, a*, b* values) and subjective muscle colour scores recorded using a nine-point colour scale (P<0.05) for both entire and castrated bucks. Muscle redness (a* values) and subjective muscle colour scores increased gradually in older animals while muscle lightness and yellowness (L* and b* values) decreased. Subcutaneous fat colour became more yellow at heavier slaughter weights (P<0.05). Shear force values were affected (P<0.05) by slaughter weight but not by castration of bucks. All eating quality scores were influenced by slaughter weight but not by castration, and flavour, as predicted by eating quality scores, was the most important attribute that contributed to overall acceptability of the goat meat.
The effect of tail docking on metabolizable energy requirements and carcass characteristics was studied using 80 weaned entire Awassi male lambs. Docking was performed within 3 days of birth and lambs were weaned at 90 days old. Docked and undocked lambs were randomly allocated to four groups, individually penned and offered different amounts of a pelleted concentrate diet. The pelleted diet was estimated to contain 11.8 MJ of metabolizable energy (ME) and 182 g of crude protein (CP) per kg dry matter (DM). Lambs on the high levels of intake were slaughtered at a target weight of approximately 45 kg. Other lambs were maintained on the diet for 149 days before being slaughtered. The right sides of all carcasses were cut into standardized commercial cuts then dissected into muscle, fat and bone. The soft tissue was pooled and analysed for DM, CP, ash and fat. Prediction of live-weight gain (LWG) and empty body gain for a given ME intake (MEI) was made using the growth and MEI data. MEI was expressed as MJ per kg metabolic body weight (M 0.75) per day. Tail docking had no effect (P> 0.05) on lamb growth from birth to weaning. During the post-weaning growth period, LWG and empty body gain were significantly higher (P < 0.05) for undocked lambs than docked lambs, at feeding levels between 0.31 and 0.52 MJ/kg M 0.75 per day and similar (P > 0.05) at high levels of intakes (between 0.74 and 1.1 MJ/kg M 0.75 per day). Hot and cold carcass weights were similar (P > 0.05) for the two groups. Differences in empty body weight and fleece-free empty body weight were significant (P < 0.05) only for the 0.443 to 0.522 MJ/kg M 0.75 per day level of ME intake. Predicted ME requirements were higher for docked lambs for an estimated LWG between 0 and 100 g/day and lower for higher LWG (125 to 225 g/day). Docking had no effect (P > 0.05) on food conversion efficiency (FCE). Carcasses from docked lambs had significantly lower (P< 0.001) internal plus tail fat. Pooled soft tissue excluding tail fat, for the undocked lambs contained significantly more (P< 0.01) protein, less (P< 0.001) fat, higher (P< 0.01) moisture and similar (P> 0.05) ash content.
The response of Awassi ewes to graded amounts of supplementary concentrate diet was examined for the first 12 weeks of lactation. The growth rate of lambs and their health status were also investigated. Seventy-five ewes were divided into three equal groups and given a basal roughage diet of shredded wheat straw at a rate of 750 g dry matter (DM) per ewe per day supplemented with a concentrate diet at three amounts, 950 g (low), 1150 g (medium) and 1350 g (high) of DM per ewe per day starting at the beginning of lactation. Ewes were adapted to the diet by feeding daily at a rate of 200 g per ewe during the last 6 weeks of pregnancy. The concentrate was estimated to contain 11⋅8 MJ of metabolizable energy and 182 g of crude protein per kg DM. Ewes and their offspring were housed in a partly enclosed yard. Lambs remained with their dams continuously except for the days of milk yield measurements, when they were separated from the dam for 11 or 12 h. The ewes were examined for subclinical mastitis and the incidence of scouring in lambs was recorded.
Ewes given the high level of concentrate produced more (P < 0⋅05) milk but differences between medium and low groups were significant only up to week 4 of lactation. Total milk yields during the 9 weeks test period were 58⋅5, 70⋅4 and 93⋅3 kg for the low, medium and high groups, respectively. Ewes suckling twins produced more (P < 0⋅05) milk than ewes suckling singles. The rate of weight loss was lower (P < 0⋅01) for ewes given the high feeding regime; these regained their immediate post-lambing body weight by week 10. Sex of lambs and litter size had no effect on body weight loss but ewes nursing twins tended to loose more weight during the 12 weeks suckling period. Lamb growth rates were similar (P > 0⋅05) across treatments. The daily intake of concentrate by the ewes did not affect the incidence of scouring in lambs or mastitis in ewes.
On both economical and biological grounds it is recommended to offer concentrate during the first 9 weeks of lactation at levels >950 g per ewe per day in order to produce an appreciable yield of milk and restore a positive energy balance early in the ewe lactation period.
Animals living in temperate climates are continually adapting to seasonal demands of reproduction and survival. Whilst it is well documented that ruminants show seasonal changes in both reproductive and non-reproductive physiological and behavioural characteristics (reduction of metabolic rate and appetite during the winter with respective increases during spring and summer), this information has not been fully established in the non-ruminating ungulate species of Equidae. This may be important information from a practical management perspective since groups of equids are increasingly being kept in natural conditions for the purposes of conservation grazing. The aim of this study, therefore, was to document the behavioural and physiological adaptive changes made by ponies during a 12-month period and to relate these to changes in forage availability and environment. Five mature pony stallions were kept in west Wales (4?5?W, 52?25?N) and monitored for 12 months. A range of physiological (testis size, body weight, condition score (CS), hoof growth, moult (M), pelage fibre length, depth and density) and behavioural measurements (foraging and non-foraging activities) were recorded along with monthly forage analysis (crude protein (CP), water-soluble carbohydrates (WSC)), dry matter (DM)) and environmental conditions (day length and minimum ambient temperature). All physiological measurements were significantly ( P
In The Netherlands a system has been developed for classification of live pigs based on lean meat proportion. Ultrasonic backfat thickness measurements were taken on 377 live pigs to assess the ability of the developed system for estimation of the lean meat proportion. The measurements were made at the sites mid point (half the distance from the occipital bone to the base of the tail), mid point –2·5 cm and mid point +2·5 cm, 5 cm off the dorsal mid line.
On the same day, these pigs were slaughtered and the lean meat proportions of the carcasses were estimated using the Hennessy Grading Probe (HGP). HGP measurements were taken between the third and fourth from last rib, 6 cm off the dorsal mid line on carcasses (3/4 LR). The day after slaughter, 88 left carcass sides were randomly chosen to be dissected according to a simplified European Union (EU) reference method.
From the fat thicknesses measured, the one at the site mid point on live pigs was the most accurate predictor for the EU lean meat proportion. The use of multiple site measurements, compared with a single site measurement, significantly reduced the residual standard deviation for the estimation of lean meat proportion.
The site mid point on live pigs differed in longitudinal as well as in dorsal-ventral direction from 3/4 LR on carcasses.
The results of this study suggest that multiple backfat thickness measurements on live pigs can be used for prediction of lean meat proportion with sufficient precision for practical use. Therefore, the developed system can serve as a classification system for live pigs.
The effect of two dietary electrolyte balance (dEB, Na+ + K+ - Cl-) levels (-135 and 145 mEq/kg diet) on heat production, energy and nitrogen retention in piglets was assessed. The experiment consisted of a 13-day adaptation period and a 7-day balance period in two open-circuit climate respiration chambers. Nine groups of three (4 weeks old) crossbred barrows were assigned to one of two diets (five and four groups for -135 and 145 mEq/kg dEB diets respectively). During the balance period, diets were provided at 2.3 times the energy requirement for maintenance in two equal meals daily. Total heat production for each group was determined every 9 minutes from the exchange of CO2 and O2. Faeces and urine mixture was quantitatively collected during the balance period to measure energy and nitrogen balance. Total heat production and metabolizable energy costs for maintenance tended (P < 0.10) to be higher in the 145 mEq/kg dEB group (681 and 443 kJ/kg0.75 per day respectively) than in the -135 mEq/kg dEB group (660 and 412 kJ/kg0.75 per day respectively). Differences in total heat production between the two dEB groups mainly occurred in the daytime (light period), when significance level was P < 0.01. The respiratory quotient and energy retention as fat were numerically (but not statistically significantly) lower in the 145 mEq/kg dEB group compared with -135 mEq/kg dEB. In conclusion, energy balances were similar for both treatments. However in the daytime (light period), piglets needed more energy for maintenance after ingesting a diet with a dEB level of 145 mEq/kg compared to a diet with a dEB level of -135 mEq/kg at a restricted feeding level.
The salinity tolerance of Javan rusa deer (Cervus timorensis russa) was investigated with seven stags, aged 4.5 years. Animals were offered a medium-quality chaffed lucerne hay and given five different levels of water salinity: (a) control (570 mg/kg of total dissolved salts ( TDS)) and (b) 'saline' water with TDS contents of 1000, 3500, 6000 and 8500 mg/kg. Food intake, food digestibility and nitrogen balance were not affected by increasing salt concentration in drinking water, however the drinking water (DW) intake, the total (food plus drinking) water intake and the DW:dry-matter ratio increased with increasing salt concentration. Some deer given water containing 8500 mg TDS per kg showed signs of stress which included large between-day fluctuations in water intake, opening of the orbital gland, head shaking, and rapid breathing. Rusa deer can tolerate drinking water containing 6000 mg TDS per kg for at least 9 days without harmful effect but may be unable to tolerate water with 8500 mg TDS per kg.
A series of laboratory and animal studies examined the use of chemical and biological agents to enhance the digestibility of Rhodes grass (grass) cut at 60 (young) and 100 (mature) days of regrowth and ensiled as big round bales. The treatments included an untreated control (C), a microbial inoculant (I), NaOH, CaO and NaOH plus inoculant (NaOH + I). Inoculant was grown anaerobically, using a starter culture of rumen fluid from cattle given Rhodes grass. Treatments C, 1, NaOH, NaOH + I, were offered separately to twelve dairy heifers, in a 3 X 4 randomized complete block design, repeated twice for each grass silage. C and I had substantial mould growth, compared with no visible mould in NaOH or NaOH + 1. CaO treatment was effective in preventing mould growth, but had little effect on the chemical composition and in sacco digestibility of mature grass silage. NaOH reduced NDF content and increased in sacco digestibility (P < 0.05) but not the in vivo digestibility (P > 0.05) of both mature- and young-grass silage. The effects of other treatments on nutritive value were non-significant at both stages of maturity. NaOH increased the intake of mature-grass silage by 24-26% (P < 0.05), but had little effect on the intake of young-grass silage (P > 0.05). Treatment I consistently reduced grass silage intake (P < 005) for young-grass silage. The findings of these studies show that treating mature Rhodes grass with NaOH will improve its nutritive value and reduce mould growth in conserved herbage. However none of the treatments in this study had any consistently positive effects on the in vivo nutritive value or storage quality of young-grass silage.
In three experiments the effects of replacing barley with citrus or unmolassed beet pulp in starter diets for calves was examined. In experiment 1, 40 Friesian bull calves were offered to appetite from 14 to 91 days of age one of four complete pelleted diets, each of which contained 200 g ground straw per kg and n i which the ratio of barley to pulp (citrus and beet pulp in the ratio 1:1) was 100:0 (A); 67:33 (B); 33:67 (C) and 0:100 (D). All diets contained 12·1 MJ metabolizable energy and 187 g crude protein per kg dry matter (DM). Milk replacer containing 200 g fat per kg was offered once daily (0·44 kg/day) until day 49 when the calves were abruptly weaned. Up to weaning (days 14 to 49) and after weaning (days 50 to 91) intake of DM was significantly increased by replacing barley with pulp (P < 0·05). Intakes (kg DM per day) of diets A, B, C and D were 0·31, 0·44, 0·51 and 0·50 before weaning and 2·07, 2·08, 2·23 and 2·38 after weaning. Weight gains (kg/day) of calves given pulp tended to be higher before weaning (0·44 v. 0·58 for A v. mean of B, C and D) but lower after weaning (0·73 v. 0·68) than of calves given the cereal-based diet. In experiment 2, 65 calves were given diets similar to A and C except that the pulp was supplied totally by unmolassed beet pulp, they were given only 0·35 kg milk replacer per day and weaned on day 35. The results were similar to those obtained in experiment 1; between days 14 to 84 intake was higher (P < 0·05) and there was a tendency for weight gain to be higher in calves given the diet containing pulp. The DM digestibility of the diets decreased significantly with inclusion of pulp (P < 0·05); digestibility of nitrogen was severely depressed but there was an increase in digestibility of acid-detergent fibre. Growth rate was possibly restricted by the availability of nitrogen in diets containing pulp.
In the double-muscled (DM) Belgian Blue beef (BBB) breed, caesarean section (CS) is being applied systematically as a management tool to prevent dystocia. As a matter of fact, CS is the only possible way of calving in the breed. High birth weight and a relatively small pelvic area are the main causes of dystocia and, in the DM-BBB breed, the reasons for the systematically applied CS. Selection for lower birth weight and larger pelvic sizes might reduce dystocia and routine CS. Few data on inner pelvic sizes of pedigree animals are available. Using external measurements to estimate the inner pelvic sizes might be an option to resolve this problem. In this study, animals of the DM-BBB breed were measured and weighed on farms and in abattoirs. External and internal pelvic sizes increased with live weight and age of the animals. Gender had a significant influence on inner pelvic traits. Increased muscular conformation was associated with decreased inner pelvic dimensions. Models with weight, gender, age, withers height and outer pelvic width (TcTc) can be used to estimate inner pelvic sizes (R2 between 0.35 and 0.77). The estimated inner pelvic sizes can then be used to genetically evaluate pelvic traits in the DM-BBB breed. Improving weight, withers height and TcTc width in combination with lowering muscular conformation may help to decrease the high rate of caesarean section in the DM-BBB.
A deterministic simulation model was constructed to develop breeding objectives and estimate biological and economic values. The model simulates life-cycle production of a breeding cow and growth performance of her offspring. Input variables are divided into four categories: animal traits, nutritional variables, management variables and economic variables. The economic variables assume typical beef cattle production in Japan. The outputs from the model include cow-calf performance, feedlot performance and biological and economic efficiency. The model's ability to simulate herd composition, food intake of cow and calves, cow body-weight changes, empty body and carcass composition of feedlot animals and production efficiencies is illustrated.
A deterministic bio-economic model simulating beef production during the life cycle of a cow and her offspring was used to estimate biological and economic values of daily gain, marbling score, birth weight, weaning weight and mature weight for three production systems (cow-calf, feedlot and integrated) and alternative production circumstances in Japan. Biological efficiency (live-weight basis and lean-weight basis) and economic efficiency (returns over costs) were regarded as breeding objectives. Alternatives included reducing the maximum number of reproductive cycles, marketing by constant slaughter weight (BASE), constant age or constant carcass fat content, lighter slaughter weight and doubling food prices. Biological efficiency on a live-weight basis for the cow-calf system was most influenced by increasing weaning weight; for the feedlot and integrated system, increasing daily gain had the largest influence. For biological efficiency of lean production, increasing daily gain and mature weight had the largest influence in the feedlot and integrated systems, respectively. For economic efficiency, increasing weaning weight was most beneficial in the cow-calf system and increasing marbling score was most beneficial in the feedlot and integrated systems. Economic values of daily gain and weaning weight decreased markedly with increasing genetic levels of these traits. Marketing by age decreased the biological values of daily gain but increased the economic value of daily gain. Marketing at a constant carcass fat content decreased biological values of mature weight but increased the economic value of mature weight. Decreasing slaughter weight provided negative economic values of daily gain and weaning weight. Economic values were reduced when food prices were doubled.
Ten Hereford 5 Friesian steers prepared with rumen, duodenal and ileal cannulae were offered ad libitum access to either grass (G), white clover (W) or red clover (R) silage or mixtures of the grass silage with the clover silages (GW and GR; 60 : 40 dry matter (DM) basis). The experiment was conducted as a two-period change-over design within each clover treatment, with grass silage as an experimental control. The clover silages had higher concentrations of DM, nitrogen (N), and total fatty acids and lower concentrations of fibre (P
Four groups of eight primiparous ewes and their single lambs were grazed for 2 weeks on pasture containing one of four novel grass species - perennial ryegrass, timothy, cocksfoot and red fescue. When subsequently grazed in a field with randomized plots of the four species, both ewes and lambs spent longer grazing the species to which they had been accustomed than was spent by ewes and lambs accustomed to other species. This effect was proportionately greater for the lambs than the ewes, and the lambs responded most to experience of cocksfoot and red fescue. Both ewes and lambs spent most time grazing perennial ryegrass and timothy, and least time grazing red fescue, with cocksfoot intermediate. It is concluded that perennial ryegrass and timothy are grazed by ewes and lambs in preference to cocksfoot and red fescue, but that a two week period of experience will increase the attractiveness of the less-preferred species, particularly to lambs.
Producers of domestic livestock strive to improve genetic influences in their herds. This requires identification, and propagation of animals that demonstrate desirable characteristics. The more animals available from which to select, the greater the opportunity to discover high-performance animals. Predetermination of the sex of offspring would provide a greater number of males or females from which to select the top individuals that will contribute the genetics to the next generation. Many attempts at sexing semen and identification of sex in preimplantation embryos have been mildly successful. However, recent advances in gene amplification enable investigators to use sex-specific probes to determine sex in only 1 cell removed from embryos. The biopsy method has had variable success in fresh embryos. However, manipulation of cryopreserved embryos reduces viability of the embryos (Bredbacka, 1998). Therefore, novel approaches to improve pregnancy rates may result in effective reproductive rates. One such approach is to vary the number of manipulated, cryopreserved embryos transferred into each recipient to increase the chances of successful pregnancy. The research performed identified the most successful techniques to biopsy and sex embryos using the mouse as a model animal. DNA from collected cells was amplified using polymerase chain reaction (PCR) or sex specific probes to determine sex. Secondly, the most effective techniques were applied to cattle embryos and survival rates in micromanipulated, cryopreserved embryos were determined. Finally, recipients were implanted with one or two embryos that sex had been previously determined. Pregnancy rates, including the incidence of twinning, were recorded. The hypothesis tested was: a single method for sexing bovine cryopreserved embryos can yield high accuracy and high pregnancy rates for the desired sex.
This paper presents an analysis of nematode faecal egg counts from Scottish Blackface ewes facing mixed, natural nematode infections (predominantly Teladorsagia circumcincta). The data set comprised 1445 measurements on 421 ewes taken at 4 and 6 weeks post-lambing, over a 4-year period. The ewes, themselves, were the progeny of 73 sires and 285 dams. Only Strongyle eggs were consistently present, and faecal egg counts from this genera ranged from zero (0·4 of all measurements) to 3388 eggs per g. Faecal egg counts were significantly affected by the number of lambs reared and suckled (increasing reproductive burden led to higher counts) by ewe age (older ewes had lower counts) and by previous selection history (ewes from a line previously selected for increased carcass fatness had lower faecal egg counts than ewes from a conversely selected lean line). The heritability of log-transformed faecal egg counts was 0·23 (s.e. 0·05) and the repeatability, including both within-and between-year permanent environmental effects, was 0·25 (s.e. 0·04). The apparent presence or absence of infection had a heritability of 0·15 (s.e. 0·07) on the observed scale and 0·39 (s.e. 0·16) when analysed as a binomial threshold trait. The genetic correlation between average 4-week weight of lamb suckled by the ewe and faecal egg counts was 0·24 (s.e. 0·10). The results suggest that faecal egg counts during early lactation are heritable and influenced by the reproductive performance of the ewe. Selection to reduce nematode faecal egg output from ewes during this period should be successful in reducing pasture larval contamination.
Estimates of genetic parameters for beef production traits were obtained for Piemontese cattle. Data were from 988 young bulls station-tested from 1989 till 1998. Bulls entered the station at 6 to 8 weeks of age and, after an adaptation period of 3 months, were tested for growth, live fleshiness and bone thinness. Length of test was 196 days. Growth traits considered were gain at farm, gain during the adaptation period, gain on test and total gain at the station. Six different fleshiness traits and bone thinness were scored on live animals at the end of the test using a linear system. Live evaluations of fleshiness were adjusted for the weight at scoring in order to provide an assessment of conformation independent of body size. Genetic parameters were estimated using animal models. Heritability of live-weight gain ranged from 0·20 in the adaptation period to 0·60 for total gain at the station. Genetic correlations between gains at station in different periods were high (from 0·63 to 0·97). Residual correlation between gain during the adaptation period and gain during test was negative, probably due to the occurrence of compensatory growth of the animals.
Live fleshiness traits and bone thinness were of moderate to high heritability (from 0·34 to 0·55) and highly correlated indicating that heavy muscled bulls also have thin bones. Accuracy of breeding values and therefore response to selection were improved by multiple trait analysis of the live fleshiness traits and bone thinness. Overall weight gain at the station had a moderate negative genetic correlation with all live fleshiness traits and bone thinness (from –0·11 to –0·39).
A study was conducted to find early predictors of the Booroola gene in several generations of a crossbred sheep population. Merino carriers of the Booroola gene were mated with Texel sheep to improve prolificacy of the latter. Ovulation rate at 8 months of age, litter size at 1 and 2 years of age and FSH and inhibin levels at 3, 4, 5 and 6 weeks of age were determined in about 700 females. Gibbs sampling was applied for inference in a mixed inheritance model. Estimates for the gene effect in heterozygous females were +1.5 corpora lutea and +1.3 lambs at 2 years of age. The gene effect on litter size at 1 year was small. The only significant major gene effect for hormone levels found was for lnINH4 (-0.66). A number of hormone levels and combinations of hormone levels appeared to be useful predictors of carrier status of individual animals. In comparison with a situation where only parents' genotype is known, posterior probabilities for non-carriers were on average increased from 50 to over 95% when FSH levels were used. However, the combined posterior probabilities of carriers and non-carriers increased only up to 67%. So in general, classification with Gibbs sampling resulted in too few animals being identified as carrier. The sum of FSH levels at 3, 4, 5 and 6 weeks of age is proposed as a predictor of presence of the Booroola gene in an animal. Multivariate analysis of mixed inheritance models could help to find more effective combinations.
Genetic parameters for pre-weaning live weights and ultrasonic scanning measurements were estimated from a flock of Scottish Blackface sheep undergoing an embryo transfer programme. Maternal environmental effects could be evaluated without confounding with maternal genetic effects because embryos were transferred to unrelated recipient ewes. The data for the study were collected over a 7-year period (1993-1999) and related to a conventional hill farming system. The data were from 1465 lambs, the progeny of 60 sires, 263 donors and 784 recipient ewes. The only exception to the conventional farming system was at mating time when embryos were collected from selected donor ewes, following superovulation, and transferred to unrelated recipient ewes. Maternal environmental effects were important for birth weight (BW), 4-week weight (W4) and weaning weight (WW) but of less importance for ultrasonic fat depth (UFD), muscle depth (UMD) and muscle width (UMW). The heritabilities of the pre-weaning weights were moderate (0.17 to 0.23). The heritabilities of UFD and UMD were 0.44 and 0.27 respectively and were higher than found in previous similar studies. The heritability of UMW was low, 0.06. The genetic and phenotypic correlations among the pre-weaning weight traits were positive and moderate. There was a positive genetic ( + 0.25) and phenotypic ( + 0.24) correlation between UFD and UMD. The phenotypic and genetic correlations between BW and W4 and the scanning traits (UFD, UMD and UMW) were close to zero, and the correlations of WW with UFD, UMD and UMW were positive. The results of this study clearly demonstrate the importance of maternal environmental effects for lamb weights up to weaning and also suggest that genetic improvement for carcass composition in some populations of extensively reared hill sheep could be achieved more rapidly than previously thought possible.