Evaluation of long-acting implant programs for calf-fed Holsteins

Abstract

ABSTRACT Objective Our objective was to evaluate the relative efficacy of 3 implant programs on performance, carcass, and health outcomes in calf-fed Holstein steers. Materials and Methods Holstein steers (n = 14,360; initial BW: 147 ± 4.5 kg) were allocated to CS1CH (Synovex C at arrival, Synovex One Feedlot at d 101, and Synovex Choice at d 271; Zoetis Inc., Parsippany, NJ), DS1CH (Synovex One Feedlot at d 101 and Synovex Choice at d 272), or DXSCH [Revalor-XS (Merck Animal Health, Summit, NJ) at d 101 and Synovex Choice at d 273). Results and Discussion Steers in the CS1CH and DS1CH groups had greater ADG compared with those in DXSCH. Steers in the DS1CH group also had improved G:F compared with CS1CH and DXSCH. Steers in the CS1CH and DS1CH groups had greater proportions of Choice and Prime and lesser proportions of YG 1 and 2 carcasses compared with DXSCH. Initial buller treatment rates were lower in the CS1CH and DS1CH groups compared with DXSCH. Overall mortality was not different between the experimental groups. Implications and Applications Holstein steers implanted with a Synovex One Feedlot implant had greater G:F and improved QG distribution compared with steers given a Revalor-XS implant, when both were administered at 101 d on feed. Including a low-dose implant at arrival did not improve performance and was detrimental to feed conversion and buller rates. These results demonstrate that the payout pattern of long-acting implants affects performance, carcass characteristics, and health of Holstein steers.