Johnston D J, Thompson J M, Hammond K
Animal Genetics and Breeding Unit, Armidale, New South Wales, Australia.
J Anim Sci. 1992 Sep;70(9):2688-94. doi: 10.2527/1992.7092688x.
Postweaning growth and carcass characters of 110 steers from a complete two-breed diallel of the Devon and Hereford breeds were examined under two environments. Additive and nonadditive effects were estimated using linear contrasts for several growth and carcass traits. Steers from each of the four breed groups were grown postweaning to slaughter in high- and low-nutrition environments. Weights were recorded every 2 mo. At slaughter, hot carcass weight, longissimus muscle area, kidney and channel fat, and subcutaneous fat at nine sites were measured. Heterosis for postweaning growth rate was 3.9% (P less than .01) and for slaughter weight 5.0% (P less than .01). Within the low-nutrition environment during periods of slow and fast growth, the Devons and Herefords performed differently. The growth rate of the steers differed in the two environments; however, heterosis for slaughter weight was of the same magnitude in both environments. No differences existed between the straightbreds or between the reciprocal crosses for slaughter weight. Crossbred carcasses were 7.4% heavier (P less than .01) than the straightbred carcasses; however, this effect was removed after adjustment for differences in slaughter weight. Heterosis for longissimus muscle area and carcass fatness were not significant after adjusting for carcass weight. Additive differences occurred for carcass traits. Devon carcasses had more kidney and channel fat (P less than .05) at a constant hot carcass weight and differences occurred in the partitioning of fat within the subcutaneous depot. No significant maternal effects were observed for the carcass traits measured. Crossbreeding increased carcass weight without altering composition, and relative performance was not affected by the diverse environments.
在两种环境下，对来自德文牛和赫里福德牛完整双品种轮交的110头阉牛断奶后的生长性能和胴体性状进行了研究。利用线性对比估计了几种生长和胴体性状的加性和非加性效应。四个品种组的阉牛在断奶后分别在高营养和低营养环境中饲养至屠宰。每两个月记录一次体重。屠宰时，测量热胴体重、背最长肌面积、肾周和肋间脂肪以及九个部位的皮下脂肪。断奶后生长速度的杂种优势为3.9%（P＜0.01），屠宰体重的杂种优势为5.0%（P＜0.01）。在低营养环境下，生长缓慢和快速时期，德文牛和赫里福德牛的表现不同。阉牛在两种环境下的生长速度不同；然而，屠宰体重的杂种优势在两种环境中大小相同。纯种牛或正反交组合的屠宰体重没有差异。杂种胴体比纯种胴体重7.4%（P＜0.01）；然而，在调整屠宰体重差异后，这种效应消失了。调整胴体重后，背最长肌面积和胴体脂肪含量的杂种优势不显著。胴体性状存在加性差异。在热胴体重恒定的情况下，德文牛的胴体有更多的肾周和肋间脂肪（P＜0.05），皮下脂肪库内的脂肪分配也存在差异。在所测量的胴体性状中未观察到显著的母体效应。杂交增加了胴体重而不改变组成，相对性能不受不同环境的影响。
