Urick J J, Pahnish O F, Knapp B W, Reynolds W L, Milmine W L
U.S. Department of Agriculture, Miles City, Montana.
J Anim Sci. 1989 Oct;67(10):2603-8. doi: 10.2527/jas1989.67102603x.
Data collected from steer and bull progeny, fed to a constant final feedlot weight over 11 yr, were used to estimate heterosis in post-weaning feedlot growth and carcass traits in two-way and three-way rotational crossing systems and a breed composite from crossing Hereford, Angus and Charolais breeds. Steer and bull progeny from matings of beef x Brown Swiss-cross sires and dams also were compared with the straight beef breeds and beef crosses. Growth traits evaluated were initial weight on test, 112-d weight, total feedlot average daily gain and total days from initial to final weight. Carcass traits included hot carcass weight, dressing percentage, rib eye area, 12th-rib fat thickness, kidney, pelvic and heart fat, yield grade and marbling score. Heterosis estimates for calves of all crossing systems were significant for initial and 112-d weight and for saving of days in the feedlot, but not for average daily feedlot gain. Heterosis estimates were small and nonsignificant for most carcass traits except for fat traits in specific crosses. Males from Hereford and Angus sires mated to Angus x Hereford dams had higher (P less than .10) backfat than did the parental average. Male progeny from Charolais ranked higher (P less than .10 to P less than .01) than calves from Hereford and Angus sires for most growth traits. Progeny from Charolais sires were more desirable (P less than .10 to P less than .01) for traits related to cutability, but they had less (P less than .05 to P less than .01) marbling than calves of Angus sires.(ABSTRACT TRUNCATED AT 250 WORDS)
从11年期间育肥牛和公牛后代的数据中收集信息，这些牛被饲养至相同的最终育肥体重，用于估计断奶后育肥生长和胴体性状的杂种优势，涉及两品种和三品种轮回杂交系统以及由海福特牛、安格斯牛和夏洛来牛杂交而成的品种组合。还将肉牛与瑞士褐牛杂交的公牛和母牛后代与纯种肉牛品种及肉牛杂交品种进行了比较。评估的生长性状包括试验初始体重、112天体重、育肥期总平均日增重以及从初始体重到最终体重的总天数。胴体性状包括热胴体重、屠宰率、眼肌面积、第12肋骨处脂肪厚度、肾、盆腔和心脏脂肪、产肉等级和大理石花纹评分。所有杂交系统犊牛的杂种优势估计在初始体重和112天体重以及育肥期天数节省方面均显著，但在育肥期平均日增重方面不显著。除特定杂交中的脂肪性状外，大多数胴体性状的杂种优势估计值较小且不显著。与安格斯×海福特母牛交配的海福特和安格斯公牛所产雄性后代的背膘厚高于亲本平均值（P<0.10）。在大多数生长性状方面，夏洛来公牛的雄性后代排名高于海福特和安格斯公牛所产犊牛（P<0.10至P<0.01）。夏洛来公牛所产后代在与可切割性相关的性状方面更优（P<0.10至P<0.01），但与安格斯公牛所产犊牛相比，其大理石花纹较少（P<0.05至P<0.01）。（摘要截选至250字）
