The Effects of Different Implant and Feed Additive Strategies on Performance and Carcass Characteristics in Finishing Heifers: A Review

Abstract

Data from 14 trials were pooled to determine the effects of nine different implant strategies for finishing heifers. The nine implant strategies involved single implant programs and reimplant programs with estrogen and androgen combinations. Feed intake, average daily gain, feed to gain, days on feed, dressing percentage, fat thickness, percentage choice, and percentage yield grades 4 and 5 were analyzed for the nine implant strategies for heifers. Average daily gains were significantly (P < .05) improved with reimplantation and as higher levels of estrogen and androgen was incorporated into the strategies. Feed to gain was improved (P < .05) by inclusions of reimplantation of estrogen and androgen combinations. Heifers were fed to heavier weights when androgens were included in the implant strategy. The percentage choice was reduced (P < .05) when estrogen plus androgen was used twice in the implant program when compared with single implant strategies. No differences for percentage yield grades 4 and 5 were detected in the nine implant strategies. Feeding of melengestrol acetate did not show an interaction with the nine implant strategies. Although there are complications with pooling data, the pooled analysis illustrated that heifers responded positively to implants containing androgen and estrogen.