Hufstedler G D, Gillman P L, Carstens G E, Greene L W, Turner N D
Department of Animal Science, Texas A&M University, College Station 77843-2471, USA.
J Anim Sci. 1996 Oct;74(10):2376-84. doi: 10.2527/1996.74102376x.
Forty crossbred wethers (average weight 30 kg) were implanted with zeranol (12 mg) at 30-d intervals and fed at two levels of intake in a 2 x 2 factorial arrangement of treatments to determine performance, carcass and bone characteristics, blood metabolites, and hormones. Restricted lambs were fed to gain one-half the BW gained by lambs with ad libitum feed access. Lambs with ad libitum and restricted access to feed were slaughtered after 98 and 154 d, respectively. Zeranol increased ADG (P = .047; 20%), gain to feed (P = .023; 17%), metacarpal length (P = .004; 6%) and weight (P = .013; 13%), and tended to increase carcass crude protein gain (P = .106; 63%) while reducing kidney pelvic fat (P = .001; 33%) and dressing percentage (P = .038; 3%). Restricted feed intake increased the percentage of carcass ash and metacarpal length and weight by 27% (P = .048), 5% (P = .006), and 10% (P = .045), respectively, while reducing quality grade scores (P = .022; 5%), gain to feed (P = .001; 49%), longissimus muscle area (P = .001; 28%), the percentage of kidney pelvic fat (P = .033; 13%), and daily fat gain (P = .001; 54%). Zeranol increased pituitary weight (P = .001; 166%), plasma glucose (P = .036; 13%), mean serum growth hormone (GH; P = .011; 52%), baseline GH (P = .048; 34%), GH pulse amplitude (P = .003; 59%), and IGF-I (P = .001; 53%) concentrations. The results indicate that continuous administration of zeranol from 60 d of age to slaughter increases GH release, which directs nutrient utilization such that a carcass with more desirable lean and fat deposition patterns is obtained when nutrient availability is adequate.
选用40只杂种阉羊（平均体重30千克），每隔30天植入12毫克玉米赤霉醇，并按照2×2析因设计的处理方式，以两种采食量水平进行饲养，以测定其生产性能、胴体和骨骼特征、血液代谢物及激素水平。限饲组羔羊的采食量为自由采食组羔羊采食量的一半。自由采食组和限饲组羔羊分别在98天和154天后屠宰。玉米赤霉醇提高了平均日增重（P = 0.047；提高20%）、增重耗料比（P = 0.023；提高17%）、掌骨长度（P = 0.004；提高6%）和掌骨重量（P = 0.013；提高13%），并使胴体粗蛋白增加量有提高趋势（P = 0.106；提高63%），同时降低了肾周脂肪（P = 0.001；降低33%）和屠宰率（P = 0.038；降低3%）。限饲提高了胴体灰分百分比、掌骨长度和重量，分别提高了27%（P = 0.048）、5%（P = 0.006）和10%（P = 0.045），同时降低了质量等级评分（P = 0.022；降低5%）、增重耗料比（P = 0.001；降低49%）、背最长肌面积（P = 0.001；降低28%）、肾周脂肪百分比（P = 0.033；降低13%）和日脂肪沉积量（P = 0.001；降低54%）。玉米赤霉醇增加了垂体重量（P = 0.001；增加166%）、血浆葡萄糖（P = 0.036；增加13%）、血清平均生长激素（GH；P = 0.011；增加52%）、基础GH（P = 0.048；增加34%）、GH脉冲幅度（P = 0.003；增加59%）和胰岛素样生长因子-I（IGF-I；P = 0.001；增加53%）的浓度。结果表明，从60日龄至屠宰持续施用玉米赤霉醇可增加GH释放，从而引导营养物质的利用，使得在营养供应充足时可获得具有更理想瘦肉和脂肪沉积模式的胴体。
