Effects of Extended-release Eprinomectin on Replacement Heifer Performance and Reproductive Success

Abstract

This study evaluated the effect of extended-release eprinomectin on production parameters and reproductive success of yearling fall replacement heifers. Heifers were treated with an ivermectin (CONV) or an injectable extended-release eprinomectin (EPR). There were no differences between treatments at initial body weight (BW). However, subsequent body weights taken 7 months and 12-months post-treatment demonstrated heavier body weight, greater overall weight gain and a greater average daily gain for heifers treated with EPR. Heifers treated with EPR had greater pregnancy rates to AI and greater overall pregnancy rates than CONV. Also, a greater proportion of EPR heifers calved in the first 21 days of the subsequent calving season. Results from this study indicate improved performance and greater reproductive success for replacement heifers treated with extended-release eprinomectin.