Phenotypic analysis of abortion incidence in Iranian Holstein cows

This study was performed to investigate the incidence of abortion based on different definitions and, the effect of climate and herd size on abortion as well as its phenotypic trend. Using calving records collected from 16 dairy herds from years 2004 through 2014. Incidence rate and analysis of affecting factors on abortion were done using the FREQ and GENMOD procedures of SAS software, respectively. According to the definition of abortion as death and expulsion of fetus between 60-260 d, 100-260 d or 150-260 d of pregnancy, overall abortion incidence was 15.5%, 11.25% and 6.6%, respectively. Herd size, climate, parity, year and season of calving as well as the interaction of calving year × season and climate × calving year were associated with abortion (P