Cole N A, Hutcheson D P, McLaren J B, Phillips W A
J Anim Sci. 1984 Mar;58(3):527-34. doi: 10.2527/jas1984.583527x.
Two trials were conducted to determine the influence of preshipment zeranol implant and protein and urea levels of the feedlot receiving diet on the performance of yearling steers. In each trial, one-half of the steers were implanted with 36 mg of zeranol 30 d before shipment from El Reno, Oklahoma to Bushland, Texas. In trial 1, receiving diets were fed to 14 d and contained 10.6 (LP), 12.6 (MP), or 16.0% (HP) crude protein (DM basis). A fourth diet contained 10.8% protein with 7% of total N from urea (LPU). In trial 2, receiving diets were also fed for 14 d and contained 12.4 (MP) or 16.7 (HP) protein. Two other diets contained about 16% protein with either 15% HPMU) or 30% (HPHU) of total N from urea. After 14 d on the receiving diets, calves were fed a 70% concentrate intermediate diet for 7 d and were fed an 85% concentrate finishing diet until the end of both trials. Zeranol implants did not significantly affect marketing-transit weight changes, but increased (P less than .05) daily weight gains at all time periods in both trials. In trial 1 on d 14, steers fed the HP diet tended (P less than .10) to have faster gains and greater gain/feed than steers fed the LP and LPU diets, with steers fed the MP diet being intermediate.(ABSTRACT TRUNCATED AT 250 WORDS)
进行了两项试验，以确定装运前玉米赤霉醇植入以及饲养场接收日粮的蛋白质和尿素水平对一岁公牛生长性能的影响。在每项试验中，一半的公牛在从俄克拉荷马州埃尔里诺运往得克萨斯州布什兰之前30天植入36毫克玉米赤霉醇。在试验1中，接收日粮饲喂14天，粗蛋白含量分别为10.6%（低蛋白，LP）、12.6%（中等蛋白，MP）或16.0%（高蛋白，HP）（以干物质计）。第四种日粮含10.8%的蛋白质，其中7%的总氮来自尿素（低蛋白尿素日粮，LPU）。在试验2中，接收日粮同样饲喂14天，蛋白质含量分别为12.4%（MP）或16.7%（HP）。另外两种日粮含约16%的蛋白质，其中总氮的15%（高比例中等蛋白尿素日粮，HPMU）或30%（高比例高蛋白尿素日粮，HPHU）来自尿素。在饲喂接收日粮14天后，犊牛饲喂7天70%精料的中期日粮，并饲喂85%精料的育肥日粮直至两项试验结束。玉米赤霉醇植入对运输期体重变化无显著影响，但在两项试验的所有时间段均增加了（P<0.05）日增重。在试验1的第14天，饲喂HP日粮的公牛比饲喂LP和LPU日粮的公牛增重更快且料重比更高（P<0.10），饲喂MP日粮的公牛表现居中。（摘要截短至250词）
