The effect of castration age, method and implant regime on growth and carcass traits of male beef cattle

Abstract

In 1984–1985 and 1985–1986 groups of 136 and 127 male calves were used to assess the effects of multiple implants (Ralgro and Steeroid), castration time (early and late) and castration method (surgical and chemical) on growth to weaning and feedlot performance and carcass characteristics. Ralgro increased calf rate of gain to weaning (P < 0.05) and adjusted weaning weight (P < 0.01) but did not affect rate of gain during the feedlot period. Although Ralgro increased (P < 0.001) weight at slaughter, it took longer (P < 0.05) for implanted cattle to reach Canada A1 than unimplanted cattle. Steeroid did not affect rate of gain to weaning but did increase (P < 0.05) adjusted weaning weight. Steeroid increased (P < 0.05) rate of gain relative to unimplanted cattle during the growing period in the feedlot and cattle implanted four times from birth to slaughter gained more (P < 0.05) than cattle implanted twice (birth and weaning). For the entire feedlot period, bulls receiving Steeroid gained faster (P < 0.05) than unimplanted bulls with no difference (P > 0.05) between implant groups (two or four implants). Ralgro implants increased (P < 0.05) carcass weight, rib-eye area and cutability while Steeroid increased (P < 0.05) only carcass weight. However, when rib-eye area was adjusted for carcass weight, the effect of Ralgro was not significant (P > 0.05). Bulls had greater (P < 0.05) shipping weight, carcass weight, rib-eye area, dressing percent and cutability than steers. Age at castration (early or late) had no effect on feedlot performance or carcass traits while method of castration (surgical or chemical) had some effects (P < 0.05) on ADG, liveweight, carcass weight and rib-eye area. Key words: Castration, Ralgro, Steeroid, beef, growth, carcass