253 Evaluation of 4 implant strategies on feedyard and carcass parameters in calf-fed beef x dairy calves.

Abstract The objective of this experiment was to evaluate the effects on feedyard performance and carcass parameters of four different implant strategies imposed on beef x dairy calf-fed steers and heifers. There were 660 steers (169 kg) and 685 heifers (167 kg) that were predominantly Charolais x Holstein cross calves randomized to one of four implant strategies at d 0 and fed for an average of 382 d. Calves were fed in mixed pens by sex with equal number of treatments contained in each pen. The treatments consisted of ChOne (Synovex-Choice administered on d 100 followed by SynovexOne-Feedyard administered on d 200 to both sexes), ChPlus (Synovex-Choice administered on d 200 followed by Synovex-Plus on d 300 to both sexes), RevXSXH100 (Revalor-XS or Revalor-XH administered on d 100 by sex), or RevXSXH200 (Revalor-XS or Revalor-XH administered on d 200 by sex). No significant (P >0.05) interaction was noted between treatment and sex, therefore only interactive means are reported. No differences were noted for Morbidity (P >0.65), Mortality (P >0.78), or Realizers (P >0.41). There were 5 bullers reported during the duration of the trial and equally distributed across treatments. On d 200 ChOne and RevXSXH100 exhibited greater (P=0.001) body weights and improved ADG (P=0.001) following the administration of their respective implants on d 100 in comparison to the two treatments which did not receive an implant. By d 300 RevXSXH100 exhibited the heaviest body weight (P=0.03) with ChPlus being significantly lighter. No significant difference was found for ADG among the treatments (P=0.06). At harvest final body weights for RevXSXH100 and RevXSXH200 were heaviest (P=0.01), and lightest for ChPlus while ChOne was intermediate. Similarly, ADG followed this same pattern with RevXSXH100 and RevXSXH200 improving (P=0.02) ADG over ChPlus while ChOne was intermediate. Hot Carcass Weight was heavier (P=0.02) for the RevXSXH100 and RevXSXH200 vs ChPlus with ChOne again being intermediate. No difference in marbling (P=0.13) or quality grade distributions (P=0.18) were noted between treatments. These data tend to indicate delaying implanting with Revalor-XS or Revalor-XH for 100 or 200 d in a 382 d feeding period, in order to meet the FDA regulations on use of implants in long day fed Beef x Dairy cross cattle, can be a viable option in comparison to FDA approved reimplanting strategies in terms of Feedyard Performance, Carcass Performance, Cattle Economics, Labor, and Feedyard Efficiency.