Pitchford W S, Deland M P B, Siebert B D, Malau-Aduli A E O, Bottema C D K
J Anim Sci. 2002 Nov;80(11):2825-32. doi: 10.2527/2002.80112825x.
Mature Hereford cows (766) were mated to 97 sires from seven breeds (Jersey, Wagyu, Angus, Hereford, South Devon, Limousin, and Belgian Blue), resulting in 1,215 calves born over 4 yr (1994 to 1997). These cattle comprised Australia's 'Southern Crossbreeding Project." Heifers were slaughtered at an average of 16 mo with hot standard carcass weight of 219 kg and 9 mm fat over the rump. Steers were slaughtered at an average of 23 mo with carcass weight of 319 kg and 13 mm fat over the rump. Meat and fat samples were taken from the carcass on the day after slaughter for subsequent laboratory analysis of i.m. fat content and fatty acid composition. Data were analyzed using uni- and bivariate animal models containing fixed effects of cohort, management group, birth month, and sire breed. March-born calves had fat with a 0.5 degrees C lower melting point, 0.6% higher total monounsaturated fatty acids, and 0.7% higher fatty acid desaturation index than calves born in April. Steers born in 1997 were the only cohort finished on pasture, and they had much more yellow fat than the other cohorts. Four heavy breed crosses (Angus, South Devon, Limousin, and Belgian Blue) averaged 284 kg carcass weight, followed by purebred Hereford (268 kg), Wagyu (244 kg) and Jersey (236 kg). Angus had the greatest fat depth (14.3 mm), ahead of Hereford and Wagyu (11.9 mm), Jersey (10.7 mm), South Devon and Limousin (9.9 mm) and Belgian Blue (8.0 mm). Jersey, Wagyu, and Angus had themost i.m. fat (4.6%), followed by Hereford and South Devon (3.8%), and Limousin and Belgian Blue (3.1%). The highly marbled Jersey and Wagyu had softer fat (6% lower fat melting point) than the other breeds. Angus were more highly marbled, similar to Jersey and Wagyu, but had harder fat similar to the leaner breeds. Heritabilities for all traits were low to moderate (16 to 36%). Genetic correlations between fatty add composition and carcass traits were not significant, indicating little evidence of antagonisms between traits that would prevent genetic progress in both production and quality.
766头成年海福特母牛与来自7个品种（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）的97头公牛交配，在4年（1994年至1997年）间产下了1215头小牛。这些牛组成了澳大利亚的“南十字杂交项目”。小母牛平均在16月龄时屠宰，热标准胴体重219千克，臀部脂肪厚度9毫米。阉牛平均在23月龄时屠宰，胴体重319千克，臀部脂肪厚度13毫米。屠宰后次日从胴体上采集肉和脂肪样本，用于后续肌肉内脂肪含量和脂肪酸组成的实验室分析。数据采用包含群体、管理组、出生月份和父本品种固定效应的单变量和双变量动物模型进行分析。3月份出生的小牛的脂肪熔点比4月份出生的小牛低0.5摄氏度，总单不饱和脂肪酸含量高0.6%，脂肪酸去饱和指数高0.7%。1997年出生的阉牛是唯一在牧场育肥的群体，它们的脂肪比其他群体的更黄。四个重型品种杂交牛（安格斯牛、南德文牛、利木赞牛和比利时蓝牛）的平均胴体重为284千克，其次是纯种海福特牛（268千克）、和牛（244千克）和泽西牛（236千克）。安格斯牛的脂肪厚度最大（14.3毫米），领先于海福特牛和和牛（11.9毫米）、泽西牛（10.7毫米）、南德文牛和利木赞牛（9.9毫米）以及比利时蓝牛（8.0毫米）。泽西牛、和牛和安格斯牛的肌肉内脂肪含量最高（4.6%），其次是海福特牛和南德文牛（3.8%），以及利木赞牛和比利时蓝牛（3.1%）。大理石花纹丰富的泽西牛和和牛的脂肪比其他品种更软（脂肪熔点低6%）。安格斯牛的大理石花纹更丰富，与泽西牛和和牛相似，但脂肪硬度与较瘦的品种相似。所有性状的遗传力都较低到中等（16%至36%）。脂肪酸组成与胴体性状之间的遗传相关性不显著，表明几乎没有证据表明这些性状之间存在拮抗作用，从而会阻碍生产和品质方面的遗传进展。
