An Evaluation of eprinomectin extended-release injectable (LongRange®) on the performance of yearling cattle on pasture in western Canada

Abstract

During the pre-shipment handling procedures at each of 2 feedlots of origin, mixed-breed beef steers were weighed, stratified into weight blocks, and simultaneously randomized within weight block to 1 of 2 experimental groups (LONG or IVER) prior to shipment to pasture. Animals in the LONG group (1523 animals) received a subcutaneous injection of eprinomectin extended-release injectable at a dosage of 0.45 mg/lb (1.0 mg/kg) body weight (BW) in the loose skin in front of the shoulder at allocation. Animals in the IVER group (1524 animals) received topical ivermectin applied along the top line from withers to tail head at a dosage of 0.23 mg/lb (0.5 mg/kg) BW at allocation. Animals from both experimental groups were commingled within weight block and originating feedlot after allocation and remained in these commingled groups for the duration of the study. The average days on trial was 156.6 days for the LONG group and 156.7 days for the IVER group. There was a significant increase observed with respect to weight gain (absolute difference 23 lb [10.4 kg], P<0.001) and average daily gain (difference 11.19%, P<0.001) in the LONG group compared to the IVER group. There was an economic advantage of CAD $7.66/animal in the LONG group compared to the IVER group.