Calkins C R, Clanton D C, Berg T J, Kinder J E
J Anim Sci. 1986 Mar;62(3):625-31. doi: 10.2527/jas1986.623625x.
This study was conducted to assess the impact of implanting intact beef males with protein anabolic agents at varying intervals throughout life. Ninety-six intact males were assigned to three implant treatments: 1) not implanted, 2) implanted at 9 wk of age, weaning and at 56-d intervals thereafter with a 36-mg zeranol implant or 3) estradiol implant at 9 wk of age and 68 d post-weaning. During the 118-d, post-weaning growing period, eight animals per treatment (one replication) were castrated. After a 114-d finishing period, cattle were slaughtered (average age of 13 to 14 mo). Feedlot performance, carcass and palatability data were obtained. Average daily gains and feed efficiency did not differ (P greater than .05) between zeranol and estradiol-implanted intact males. Regardless of implant treatment, steers had lighter carcass weights (P less than .05) and higher (P less than .01) quality grades than intact males. Implanting either intact males or steers with zeranol or estradiol resulted in higher (P less than .05) numerical yield grades. Quality grades were higher in zeranol-implanted cattle than the non-implanted or estradiol-implanted cattle. Intact males implanted with zeranol were similar in carcass fatness to zeranol-implanted steers. No differences (P greater than .05) in tenderness or connective tissue were detected. Implanting intact males early and throughout life with zeranol made them similar to steers in fatness, while estradiol implantation had few effects on carcass and palatability traits of intact males or steers.
本研究旨在评估在整个生命周期内不同间隔给未阉割的公牛植入蛋白质合成代谢剂的影响。96头未阉割的公牛被分配到三种植入处理组：1）不植入；2）9周龄断奶时植入，之后每隔56天植入一次36毫克的玉米赤霉醇植入剂；3）9周龄时植入雌二醇，断奶后68天再次植入。在断奶后的118天生长期间，每组处理选8头动物（一个重复）进行去势。经过114天的育肥期后，牛被屠宰（平均年龄13至14个月）。获取了饲养场性能、胴体和适口性数据。玉米赤霉醇和雌二醇植入的未阉割公牛之间的平均日增重和饲料效率没有差异（P>0.05）。无论植入处理如何，阉牛的胴体重都较轻（P<0.05），品质等级高于未阉割的公牛（P<0.01）。给未阉割的公牛或阉牛植入玉米赤霉醇或雌二醇会使产量等级数值更高（P<0.05）。植入玉米赤霉醇的牛的品质等级高于未植入或植入雌二醇的牛。植入玉米赤霉醇的未阉割公牛的胴体脂肪含量与植入玉米赤霉醇的阉牛相似。在嫩度或结缔组织方面未检测到差异（P>0.05）。在早期及整个生命周期给未阉割的公牛植入玉米赤霉醇，使其脂肪含量与阉牛相似，而植入雌二醇对未阉割公牛或阉牛的胴体和适口性性状影响较小。
