Whole milk progesterone analysis used for pregnancy diagnosis in beef cattle

In Finland the routinely used method to determine milk progesterone level is based on whole milk analysis (Progesterone RIA-kit for Veterinary Diagnostic use, Farmos Group ltd.). The method is standardised for milk samples which are taken from the udder just after the cow has been milked. This kind of aftermilk sample contains a high percentage of fat and–as progesterone is lipidofil–also large, sexual-cycle correlated, variability in milk progesterone.     

Investigation of genotype x country interactions for growth traits in beef cattle

The importance of genotype x country interactions for weaning and birth weight and postweaning gain between Argentina (AR), Canada (CA), Uruguay (UY), and the United States (US) for populations of Hereford cattle was investigated. Three sample data sets of computationally manageable sizes were formed for each trait and pairwise combination of countries to investigate possible interactions. Parameters were estimated for each sample data set via an accelerated EM-REML algorithm and multiple-trait animal models that considered either weaning or birth weight as a different trait in each country. Direct and maternal (in parentheses) weaning weight genetic correlation estimates for AR-CA, AR-UY, AR-US, CA-UY, CA-US, and UY-US were 0.82 (0.80), 0.81 (0.72), 0.81 (0.79), 0.83 (0.78), 0.85 (0.82), and 0.86 (0.81), respectively. Direct and maternal (in parentheses) birth weight genetic correlation estimates were 0.92 (0.62), 0.97, (0.85), and 0.99 (0.97) for AR-CA, AR-US, and CA-US, respectively. Birth weight was not analyzed for UY due to small amounts of data. Postweaning gain in CA and US was 160-d gain, and in AR and UY 345-d gain was used. Across-country direct genetic correlations for postweaning gain were estimated for each pairwise country data set using a model that considered weaning weight as the same trait across each country, whereas postweaning gain was treated as a different trait in each country. Direct genetic correlation estimates for postweaning gain for AR-CA, AR-UY, AR-US, CA-UY, CA-US, and US-UY were 0.64, 0.80, 0.51, 0.84, 0.92, and 0.83, respectively. The overall results indicate that weaning and birth weights of Hereford calves can be analyzed as the same trait in all countries with a common set of heritabilities and genetic correlations, after adjustment for heterogenous phenotypic variances across countries. Postweaning gain in CA and US can be considered as the same trait and analyzed using a single set of parameters. Postweaning gain in AR and UY should be considered as a separate trait from postweaning gain in CA and US, and postweaning gain in AR and UY can be considered as the same trait and analyzed using a common heritability, after adjustment for phenotypic variance differences between the two countries.     

Constructing covariance functions for random regression models for growth in Gelbvieh beef cattle

Genetic parameters for a random regression model of growth in Gelbvieh beef cattle were constructed using existing estimates. Information for variances along ages was provided by parameters used for routine Gelbvieh multiple-trait evaluation, and information on correlations among different ages was provided by random regression model estimates from literature studies involving Nellore cattle. Both sources of information were combined into multiple-trait estimates; corrected for continuity, smoothness, and general agreement with literature estimates; and extrapolated to 730 d. Covariance functions using standardized Legendre polynomials were fit for the following effects: additive genetic (direct and maternal), and animal and maternal permanent environment. Residual variances at different ages were fitted using linear splines with three knots. Fit was by least squares. The order of polynomials was varied from third to sixth. Increasing the fit beyond cubic provided small improvements in R2 and increased the number of small eigenvalues of covariance matrices, especially for the additive effect. Parameters for a random regression model in beef cattle can be constructed with negligible artifacts from literature estimates. Formulas can easily be modified for other types of polynomials and splines.     

Evaluation of methods for computing approximate accuracies of predicted breeding values in maternal random regression models for growth traits in beef cattle

The objective of this study was to determine the suitability of 2 methods for computing approximate accuracies of predicted breeding values, in which accuracy was defined as the squared correlation between the predicted and true breeding value, when modeling growth traits in beef cattle using random regression (RR) models. The first method (Strabel et al., S-M-B) was designed for use with multitrait models; thus, its use with RR models requires the clustering of measurements into different traits. The second method (Tier and Meyer, T-M) was more general, because it accounted for random coefficients other than zeros and ones and thus it could be used directly when fitting RR models. To investigate the performance of both methods, their results were compared with the true accuracies using a balanced simulated data set. The largest difference between approximate and true average accuracies for direct effects was observed at 205 d when S-M-B was used (4.6% males and 8.8% females). With regard to maternal effects, the largest differences in average accuracies were observed at 205 d in males when S-M-B was used (31.8%) and at the same age in females but when using T-M (33.3%). In general, bias increased for direct effect accuracies in males at the tails of the accuracy range, but for females and for maternal effect accuracies in both sexes, bias increased as accuracy increased. When a population was simulated to create large numbers of progeny for base females that did not have individual records, much greater errors were observed in the regression of approximate values on the true ones. When both approximate methods were compared using a real beef cattle data set, a good agreement was observed, particularly for direct effect accuracies in sires [i.e., at 205 d, the regressions were 0.98 (direct) and 0.95 (maternal) with r(2) over 0.99]. The largest discrepancies for sires between the methods were observed at 205 d for direct (2.7%) and maternal (16.3%) effect accuracies. For dams, the largest differences between methods were also observed at 205 d, 9.3% (direct), and 15.2% (maternal). The differences between methods for nonparent cattle were greater than for dams for maternal effect accuracies but intermediate between sires and dams for direct effect accuracies. In spite of the less biased results provided by T-M, its use could be problematic when employed in evaluations of large populations due to its greater memory and computation requirements (e.g., 170 and 478% more than S-M-B for a population of 11 million).     

Leptin as a predictor of carcass composition in beef cattle

Our objective was to determine if serum concentrations of leptin could be used to predict carcass composition and merit in feedlot finished cattle. Two different groups of crossbred Bos taurus steers and heifers were managed under feedlot conditions near Miles City, MT. The first group consisted of 88 1/2 Red Angus, 1/4 Charolais, and 1/4 Tarentaise composite gene combination steers (CGC) harvested at the ConAgra processing facility in Greeley, CO. The second group (Lean Beef Project; LB) consisted of 91 F2 steers and heifers born to Limousin, Hereford, or Piedmontese by CGC F1 cows crossed to F1 bulls of similar breed composition and harvested at a local processing facility in Miles City, MT. Blood samples were collected approximately 24 h before harvest (CGC) or approximately 3 d before and at harvest (LB). No differences in serum concentrations of leptin were detected (P > 0.10) between Hereford, Limousin, or Piedmontese F2 calves nor between LB steers and heifers. Positive correlations (P < 0.01) existed between serum leptin and marbling score (r = 0.35 and 0.50), fat depth measured between the 12th and 13th rib (r = 0.34 and 0.46), kidney, pelvic, and heart fat (KPH) (r = 0.42 and 0.46), and quality grade (r = 0.36 and 0.49) in CGC and LB cattle, respectively. Serum leptin was also positively correlated with calculated yield grade for CGC steers (r = 0. 19; P = 0. 10) and LB cattle (r = 0.52; P < 0.01). Longissimus area was not correlated with serum leptin in CGC steers (r = 0.12; P > 0.10). However, a negative correlation existed between longissimus area and serum leptin in the LB cattle (r = -0.45; P < 0.01). Serum concentrations of leptin were significantly associated with carcass composition (marbling, back fat depth, and KPH fat) and quality grade in both groups of cattle studied and may provide an additional indicator of fat content in feedlot cattle.     

Estimates of covariances between reproduction and growth in Australian beef cattle

Estimates of covariance components between scrotal circumference, serving capacity, days to calving, and yearling and final weight were obtained for Hereford, Angus, and Zebu cross cattle in temperate and tropical Australia. Analyses were carried out by REML employing a derivative-free algorithm and fitting bivariate animal models. Aspects of modeling and computational requirements related to the use of this method are discussed. Estimates of heritabilities agreed closely with those from univariate analyses, being low for female reproductive performance and moderate to high for male reproduction and growth. Estimates of genetic correlation between male and female fertility traits were low but favorable, being -.25, -.28, and -.41 between scrotal circumference and days to calving for Herefords, Angus, and Zebu crosses, respectively. Genetic correlations between male reproductive traits and weights ranged from .24 to .52 for the temperate breeds and were higher (.65 to .69) for Zebu crosses. Phenotypic correlations between scrotal circumference and weights were similar for all breeds, ranging from .32 to .47, whereas serving capacity and weights were phenotypically unrelated. Estimates of correlations between days to calving and weights were less consistent. Phenotypically, there was little association between the two traits. Genetic correlations for Zebu crosses were negative and low to moderate (-.36 to -.66) and estimates for Angus were close to zero.     

Evaluation of three Brucella soluble antigens used in an indirect Elisa to discriminate S19 vaccinated from naturally infected cattle

An O-polysaccharide (O-chain) and a hot-water extracted polysaccharide (PS), both obtained from Brucella abortus 1119-3, and a B. melitensis 16M native hapten (NH) were evaluated by indirect enzyme linked immunosorbent assay (ELISA) on three groups of cattle sera. The sera tested were: (a) 75 sera from cows naturally infected with B. abortus; (b) 130 sera from non-infected and non-vaccinated cattle; and (c) 61 sera from non-infected heifers recently vaccinated with B. abortus Strain 19 (S19). Sensitivity (Se), specificity (Sp) and the capability to discriminate vaccinated cattle (ADV) were determined. Using PS antigen, Se was 100% and the Sp was 97.7%, while the highest Sp was obtained by using the O-chain (99.2% ). For the NH antigen, Se was 94.7% and the Sp was 90.0%. The ADV of the three antigens was approximately 85%. Statistical analysis showed significant differences between O-chain/PS and O-chain/NH antigens. The agreement among antigens determined by kappa coefficient was 0.899 for O-chain/PS, 0.845 for O-chain/NH and 0.795 for PS/NH.     

Evaluation in beef cattle of six deoxyribonucleic acid markers developed for dairy traits reveals an osteopontin polymorphism associated with postweaning growth

The objectives of this study were to 1) estimate the allelic frequencies in US beef cattle of 6 DNA markers reported to be associated with variation in dairy production traits; and 2) evaluate the association of these markers with beef production traits. Several genetic markers have been associated with milk yield or composition, including polymorphisms in secreted phosphoprotein 1 (SPP1; also called osteopontin), growth hormone receptor (GHR), casein S1 (CSN1S1), diacylglycerol O-acyltransferase 1 (DGAT1), peroxisome proliferator-activated receptor gamma co-activator-1alpha (PPARGC1A), and ATP-binding cassette subfamily G (white) member 2 (ABCG2). Allelic frequencies for these 6 markers, and their association with 21 phenotypes, were evaluated in 2 crossbred beef cattle populations that sample influential industry sires. Five of 6 markers were segregating in beef cattle populations; the exception was ABCG2. The SPP1 marker was associated with yearling weight (P = 0.025), live weight at slaughter (P = 0.016), postweaning ADG (P = 0.007), and HCW (P = 0.007) in a large, multisire population representing the 7 most populous beef breeds in the United States. Postweaning growth trait associations were confirmed in an independent population of similar construction, including sires from tropically adapted breeds. The SPP1 marker was associated with yearling weight (P = 0.034), live weight at slaughter (P = 0.011), and postweaning ADG (P = 0.015) and showed a trend toward association with HCW (P = 0.083) in this population. Whereas DGAT1, GHR, and CSN1S1 polymorphisms showed association with some traits in individual populations, the lack of consistent predictive merit between populations indicates they may not be suited for beef cattle selection. No significant associations were observed for the PPARGC1A marker and any of 21 recorded traits, indicating this marker had no apparent value in selection for the beef cattle traits tested in these populations. The SPP1 marker had consistent associations and effect sizes (10.5 to 11.5 kg of live weight at slaughter) in both populations, providing strong evidence for utility of the SPP1 marker for postweaning growth in beef cattle.     

重组微线体MIC10的牛弓形虫抗体间接ELISA检测方法的建立

为建立牛弓形虫抗体间接ELISA检测方法,根据弓形虫MIC10基因序列设计合成引物,应用PCR技术扩增MIC10基因,将其克隆至pET-22b载体,构建重组质粒pET-22b-MIC10,将其转化至E.coli BL21(DE3),经IPTG诱导,SDS-PAGE及Western-blot分析表明,该重组蛋白能与弓形虫阳性血清发生特异性反应。重组蛋白经NiNTA纯化,应用牛弓形虫阳性、阴性血清建立了ELISA检测方法,抗原最佳包被质量浓度为5mg/L,二抗稀释倍数为1∶20 000,封闭液为含5%脱脂奶粉的PBST溶液。该方法重复性好、特异性强、敏感性高,为牛弓形虫流行病学调查奠定基础。     

Evaluation of cytoplasmic genetic effects in beef cattle using an animal model

Mixed model techniques were used to evaluate the importance of cytoplasmic genetic effects on beef cattle performance. Birth weight (BWT), preweaning average daily gain (ADG), weaning weight (WT205), postweaning gain (PG), ultrasonic backfat thickness (FAT) and predicted milk yield (MILK) data were collected in two herds of Hereford cattle located at Plymouth and Raleigh, North Carolina. Cytoplasmic lines were determined based on the foundation female in the maternal lineage of each animal. An animal model was used to account for all nuclear genetic variation among animals within herds. Direct breeding values were estimated for all animals with records and their parents for all traits. For MILK, permanent environmental effects were estimated for animals with multiple records. For preweaning traits, maternal breeding values and permanent maternal environmental effects also were estimated. In all analyses, F-tests for cytoplasmic effects were not significant. Probability values approached significance (P = .15 to P = .10) only for PG and FAT at Plymouth. Assumptions regarding the ratios of genetic and environmental variances and covariances had no effect on F-tests. Results contrast with earlier analyses of the same data in which nuclear genetic effects were accounted for by including sire and maternal grandsire in the statistical model. This study failed to show that cytoplasmic genetic effects were important sources of variation in performance; residual additive genetic effects were confounded with cytoplasmic lines for these herds. Because cytoplasmic sources may be regarded as founder effects, further research is needed in other populations.     

A practical evaluation of five food additives likely to be used as growth promoters in broiler rations

An investigation is described which was designed to evaluate and compare five food additives. The investigation was carried out with about 2400 broilers and the food additives tested were virginiamycin, zinc bacitracin, a nitrofuran derivative, and two arsenical compounds. Only one treatment, one of the arsenicals, produced results economically superior to the control diet. This evaluation of the treatments relative to each other and to the control diet remained substantially similar, as far as the several production characters were concerned, in each of the two seasons in which the investigation was carried out, for each sex and for each of the two breeds of broiler used. The total weight and the weight per unit area of the wall of the small intestine was found to be higher among birds on the control diet than under each of the treatment diets.     

Effects of intake level on metabolic response to estrogenic growth promoters in beef steers

Effects of diethylstilbestrol (DES, 10 mg/d orally, Trial 1) or Synovex-S (SYN, 220 mg ear implant, Trial 2) on gain and N balance (g/d) were determined in steers that consumed 1.3, 2.7, 4.4 and 7.4 kg DM/d (Trial 1) and 1.3, 2.9, 4.3 and 6.6 kg DM/d (Trial 2). Each trial was a replicated 4 x 4 Latin square with four pairs of steers per trial (BW:322 kg, Trial 1; 278 kg Trial 2) and a control and growth promoter steer in each pair. Steers were fed a pelleted 75% concentrate diet containing 16.7% (DM basis). Each period consisted of 1 wk of intake adaptation, 5 wk of feeding and 1 wk in metabolism crates (2-d adjustment and 5-d collection). Steers were switched among DMI but not among promoter treatments. Intercept and slope, respectively, for the regression of BW gain (kg/d) on DMI (kg/d) were -.66 and .276 for control vs -.84 and .328 for DES steers and -.69 and .276 for control vs -.89 and .356 for SYN steers. Similar regression values for N balance (g/d) on DMI (kg/d) were -10.3 and 6.91 for control vs -17.2 and 9.10 for DES steers and -4.5 and 4.67 for control vs -7.6 and 5.85 for SYN steers. Across trials, slopes differed from zero (P less than .01), and promoter slopes differed from controls for gain (P less than .01) and N balance (P less than .10). During an extra period at the end of each trial, all steers were fed the high intake level for 6 wk, followed by N balance determinations the last 3 d of a 7-d fast.(ABSTRACT TRUNCATED AT 250 WORDS)     

肉牛生长性状和肉质性状全基因组关联分析的研究进展

全基因组关联分析(genome-wide association studies,GWAS)是研究家畜复杂经济性状和疾病遗传变异的有效方法,GWAS的核心是挖掘遗传变异与目标表型性状间的关系.随着牛全基因组测序工作完成,海量单核苷酸多态性(single nucleotide polymorphism,SNP)位点被标记...     

草地植物添加剂对肉牛生长性能的影响

通过对草地植物添加剂的最佳配方、最适量以及肉牛的最佳育肥方式对肉牛日增重、屠宰率、净肉率以及肉品质和风味的影响进行研究,旨在分析草地植物添加剂对肉牛生长性能的影响。结果表明,草地植物添加剂能促进肉牛的快速生长,提高肉牛的日增重,其中对于犊牛(C)、架子牛(S)和基础母牛(B)日增重效果最明显的分别是草地植物添加剂C3(44%松针+24%艾叶+12%黄芪+8%微量元素)(P0.01)、S3(48%松针+16%艾叶+8%大蒜+10%黄芪+18%微量元素)(P0.01)和B3(36%松针+14%艾叶+10%大蒜+12%黄芪+28%微量元素)(P0.01);草地植物添加剂的最适量的筛选试验表明,各年龄段的肉牛的草地植物添加剂的添加量占日粮的3.5%育肥效果最明显(P0.01);在北方冷季最佳的育肥方式为舍饲育肥。综上,在北方的寒冷季节养殖肉牛以占日粮3.5%的第3类(C3、S3、B3)草地植物添加剂配合舍饲增肥效果最明显。     

Rice mill feed as a replacement for broiler litter in diets for growing beef cattle

The efficacy of replacing broiler litter with rice mill feed was evaluated in four experiments. In Exp. 1, 40 predominantly Angus steers (initial BW = 277+/-18.2 kg) were fed four dietary treatments for 112 d (five steers per pen; two pens per diet). Dietary treatments (DM basis) were as follows: 1) 47% broiler litter:53% corn; 2) 60% rice mill feed:40% corn; 3) 50% rice mill feed:50% corn; and 4) 40% rice mill feed:60% corn. All diets, along with bermudagrass hay, were fed free choice. Daily gains were faster (P < 0.10) for the 50:50 and 40:60 diets (1.26 and 1.30 kg/d, respectively) than for the broiler litter diet (0.89 kg/d). Daily DMI was less (P < 0.10) by steers consuming rice mill feed-based diets than by those consuming broiler litter-based diets. In Exp. 2, 16 Angus x Charolais steers (initial BW = 277+/-22.7 kg) were fed the same four diets used in Exp. 1 while housed in individual metabolism stalls for determination of nutrient digestibility. Daily DMI was not different (P > 0.10) among diets. Nutrient digestibilities did not differ among diets (P > 0.10). In Exp. 3, 40 Continental cross steers (initial BW = 257+/-21.3 kg) were fed one of four dietary treatments for 112 d (five steers per pen; two pens per diet). On a DM basis, diets were as follows: 1) 47% broiler litter:53% soyhulls; 2) 70% rice mill feed:30% soyhulls; 3) 60% rice mill feed:40% soyhulls; and 4) 50% rice mill feed:50% soyhulls. All diets, along with bermudagrass hay, were fed free choice. Daily gains were less (P < 0.05) for the broiler litter diet than for the 60:40 and 50:50 diets (1.05, 1.16, and 1.28 kg/d, respectively), and steers fed the broiler litter diet consumed less DM than did steers fed the varying rice mill feed-based diets (P < 0.10). In Exp. 4, 16 Angus x Charolais steers (initial BW = 292+/-21.1 kg) were fed the same four diets as in Exp. 3 while housed in individual metabolism stalls for determination of nutrient digestibility. Daily DMI was less (P < 0.01) for the broiler litter diet (5.0 kg/d) than for the 70:30, 60:40, and 50:50 diets (7.8, 7.9, and 7.9 kg/ d, respectively). Digestibilities for DM, OM, and ADF did not differ (P > 0.10) among treatments; however, CP digestibility was greatest (P < 0.10) for the 60:40 diet, and NDF digestibility was least (P < 0.10) for the 70:30 diet. Rice mill feed can be used to replace broiler litter to formulate low-cost diets for stocker calves. Soyhulls and corn can be blended with rice mill feed to produce acceptable backgrounding diets for growing beef calves.     

壳聚糖对肉牛生长性能及营养物质消化率的影响

试验旨在研究壳聚糖(chitosan,CHI)对肉牛生长性能及营养物质表观消化率的影响。选择体重、月龄接近,健康无病的24头西门塔尔育肥公牛,随机分为3个日粮处理组,每组8头牛,饲养试验分前、中、后三期,每期28 d,共84 d。三组日粮分别是在基础日粮中添加0、500和1 000 mg/kg的壳聚糖配制而成。结果表明:试验全期500 mg/kg壳聚糖组的平均日增重(ADG)和日采食量(ADFI)最高、料肉比(F/G)最低;日粮添加500 mg/kg壳聚糖可提高肉牛干物质、蛋白质、能量和钙表观消化率。说明日粮中添加500 mg/kg壳聚糖可提高肉牛营养物质的消化率,进而促进肉牛的生长。