Afolayan R A, Pitchford W S, Deland M P B, McKiernan W A
Livestock Systems Alliance, The University of Adelaide, Roseworthy campus, Roseworthy, SA 5371, Australia.
Animal. 2007 Feb;1(1):13-20. doi: 10.1017/S1751731107257933.
Conformation scores can account for more than 20% of cattle price variation at Australian livestock sales. However, there are limited available references which define genetic factors relating objective live developmental traits to carcass composition. Weaning and post-weaning weight, height, length, girth, muscle (ratio of stifle to hip width) and fat depth of 1202 progeny from mature Hereford cows (637) mated to seven sire breeds (Jersey, Wagyu, Angus, Hereford, South Devon, Limousin and Belgian Blue) were examined for growth and development across ages. Crossbred Wagyu and Jersey were both lighter in weight and smaller in size (height, length and girth) than purebred Hereford and crossbred Angus, South Devon, Limousin and Belgian Blue. Within the five larger crossbreds, there were significant changes in relative weight from weaning to 600 days. Sire breeds differed in fat depth, with Angus being the fattest (9% on average fatter than Hereford and Wagyu), and Jersey 5% less fat than Hereford, followed by South Devon and Limousin (19% lower than Hereford) and Belgian Blue (39% lower than Hereford). Direct heritability ranged from 19 to 42% and was higher than the proportion of total phenotypic variance accounted for by maternal effects (which ranged from 0 to 17%) for most body measurement traits except for weight (38 v. 18%) and girth (36 v. 9%) traits at weaning, an indication of maternal effect on some body conformation traits at early ages. Muscularity (19 to 44%) and fat depth (26 to 43%) were moderately to highly heritable across ages. There were large differences for growth and the objective measures of body development between crossbreds with a degree of overlap among the progeny of the seven sire breeds. The variation between genetic (positive) and environmental (negative) correlations for dry versus wet season average daily gains in weight and fat, suggested the potential use of live-animal conformation traits for within breed selection of genetically superior animal in these traits across seasons.
在澳大利亚牲畜拍卖中，体型评分可解释牛价格差异的20%以上。然而，目前关于客观活体发育性状与胴体组成相关遗传因素的参考文献有限。对1202头来自成熟海福特母牛（637头）与七个父本品种（泽西牛、和牛、安格斯牛、海福特牛、南德文牛、利木赞牛和比利时蓝牛）交配所产后代的断奶及断奶后体重、身高、体长、胸围、肌肉量（膝关节与髋部宽度之比）和脂肪厚度进行了不同年龄阶段的生长发育研究。杂交和牛与杂交泽西牛在体重和体型（身高、体长和胸围）上均比纯种海福特牛以及杂交安格斯牛、南德文牛、利木赞牛和比利时蓝牛轻且小。在五个较大的杂交品种中，从断奶到600日龄相对体重有显著变化。父本品种在脂肪厚度上存在差异，安格斯牛最肥（平均比海福特牛和和牛肥9%），泽西牛比海福特牛脂肪少5%，其次是南德文牛和利木赞牛（比海福特牛低19%）以及比利时蓝牛（比海福特牛低39%）。直接遗传力范围为19%至42%，除断奶时体重（38%对18%）和胸围（36%对9%）性状外，大多数体尺性状的直接遗传力高于母体效应占总表型方差的比例（范围为0至17%），这表明在早期母体效应会影响一些体型性状。不同年龄阶段肌肉量（19%至44%）和脂肪厚度（26%至43%）具有中度到高度的遗传力。七个父本品种的后代中杂交品种在生长和身体发育客观指标方面存在较大差异且有一定重叠。干季与湿季体重和脂肪平均日增重的遗传（正）与环境（负）相关性之间的差异，表明活体体型性状在这些性状上跨季节进行品种内遗传优势动物选择方面具有潜在用途。
