Comparison of reproductive performance of dairy cattle following a post-partum vaccine protocol with two different multi-valent modified live vaccines

Abstract

More than 70% of dairy operations in the US vaccinate their cows, with increasing percentage as herd size increases (NAHMS 2014). There is evidence that vaccination in general improves the risk of pregnancy by about 5% compared to non-vaccinated animals (Newcomer et al.). Reports from the field indicate that the use of a particular modified live vaccine (Bovi-Shield Gold FP5 L5 HB) pre-breeding results in better reproduction than other modified live vaccines but there is no peer reviewed literature to support, or refute, that claim. The objectives of this study were to compare the effects of two modified live vaccines on reproductive performance in post-partum dairy cows (first service outcome {FSO}, pregnancy status at 150 days and time to pregnancy censored to 150 days).