Impact of Castration and Zeranol Implants on Bullocks: I. Behavior, Growth and Carcass Traits

摘要

The effects of Zeranol implants on behavior, feedlot performance and carcass traits were studied using 95 young intact and 98 castrated bovine males. The intact males were heavier at slaughter, (515 vs. 468 kg; P<.005) had less backfat, (0.81 vs. 1.11 cm; P<.005), larger loin eye area, (89.0 vs 76.8 cm2; P<.005), more desirable USDA yield grades (2.11 vs. 2.92; P<.005), a higher percentage of edible lean cuts (81.5 vs. 80.5), and less bone and fat trim (16.4 vs. 18.9 kg) than steers. Steers exhibited more marbling, (small+ vs. slight) a higher USDA quality grade, and reached market condition 5 d earlier than the intact males. Castration had a much greater effect on mean carcass cutout than did implant treatment. Whereas implant treatment affected percentage of blade and top sirloin, castration increased yield of every primal and subprimal cut studied except for lean trim and sirloin tip. Behavior characteristics of implanted and control bulls and steers were also studied. Implantation made bulls and steers more docile. Libido measurements were also lower for the implanted bulls as compared to non-implanted intact males. These data confirm that castration and implants have significant effects on behavior, growth and carcass characteristics of young male bovines.