Reiling B A, Berger L L, Faulkner D B, McKeith F K, Nash T G
Department of Animal Sciences, University of Illinois, Urbana 61801, USA.
J Anim Sci. 1995 Apr;73(4):986-92. doi: 10.2527/1995.734986x.
Twenty-four prenatally androgenized (PA) heifers, born to testosterone propionate-implanted cows, and 27 control (C) heifers, born to nonimplanted cows, were bred, calved, and placed in drylot pens, with calf at side, to assess the effects of PA on feedlot growth and lactational performance of heifers used in a single-calf heifer (SCH) system. Lactating heifers were fed an 85% concentrate diet, calves weaned at 117 d postpartum, and heifers slaughtered at a constant compositional end point of 1.1 cm of s.c. fat. Preweaning, PA heifers gained 22.5% faster (P < .01) and were 17.3% more efficient (P < .01) than controls. Prenatal androgenization of the heifer, however, did not affect calf growth performance. All calves gained more than 1.4 kg/d and had an average weaning weight of 159 kg at 117 d of age. Combining heifer-calf weights, PA and C pairs gained 2.88 and 2.53 kg/d, respectively. Correcting for DMI of calves, PA improved (P < .01) efficiency of beef production 10.8%. Four percent fat-corrected milk yield of PA and C heifers averaged 7.96 and 7.60 kg/d, respectively, and the percentage of milk protein and fat did not differ. Accounting for average BW, milk production, and DMI, PA and C lactating heifers should have gained 1.27 kg/d; however, gains were 137 and 127% of those predicted, respectively. Overall, pre- and postweaning, PA heifers required 10 fewer (P < .04) days on feed, gained 23% faster (P < .01), and were 16% more efficient (P < .02) than C heifers. At slaughter, PA and C heifers averaged 853 and 865 d of age, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
24头产前雄激素化（PA）的小母牛，由植入丙酸睾酮的母牛所生，以及27头对照（C）小母牛，由未植入的母牛所生，进行配种、产犊，并被安置在干奶牛栏中，小牛在旁边，以评估PA对单犊小母牛（SCH）系统中使用的小母牛育肥生长和泌乳性能的影响。泌乳小母牛饲喂85%精料日粮，小牛在产后117天断奶，小母牛在皮下脂肪厚度达到1.1厘米的恒定成分终点时屠宰。断奶前，PA小母牛的生长速度比对照快22.5%（P < 0.01），效率高17.3%（P < 0.01）。然而，小母牛的产前雄激素化对小牛的生长性能没有影响。所有小牛每天增重超过1.4千克，在117日龄时平均断奶体重为159千克。将小母牛和小牛的体重相加，PA组和C组每天分别增重2.88千克和2.53千克。校正小牛的干物质采食量后，PA提高了牛肉生产效率10.8%（P < 0.01）。PA组和C组小母牛的4%脂肪校正乳产量平均分别为7.96千克/天和7.60千克/天，乳蛋白和脂肪的百分比没有差异。考虑到平均体重、产奶量和干物质采食量，PA组和C组泌乳小母牛每天应增重1.27千克；然而，实际增重分别是预测值的137%和127%。总体而言，断奶前后，PA小母牛比C小母牛在育肥期所需天数少10天（P < 0.04），生长速度快23%（P < 0.01），效率高16%（P < 0.02）。屠宰时，PA组和C组小母牛的平均年龄分别为853天和865天。（摘要截取自250字）
