Greater Reproductive Performance in Holstein Dairy Cows with Moderate Length of Anogenital Distance at First Service Postpartum

 BACKGROUND: Previous studies have indicated negative association of anogenital distance (AGD) with fertility in dairy cows; however, the mechanism of inverse relationship is not completely understood. In this regard, post-partum uterine infections and their corresponding risk factors could diminish fertility of cows, yet there has been no research exploring the relationship between AGD and postpartum disorders. OBJECTIVES: The aim of this study was to investigate the relationship between AGD and postpartum reproduc-tive performance in dairy cows. METHODS: AGD of Holstein dairy cows of a commercial dairy herd (n = ۲۹۰) was measured in millimeter at the first postpartum examination (days ۲۸ to ۳۲ postpartum). The cows were classified into three categories based on the AGD length, including short (۲۰% of cows with lowest values), intermediate (۶۰% of cows with moderate values) and long (۲۰% of cows with highest values) AGDs. Additionally, data of postpartum reproductive variables were retrieved form the herd database. Data was analyzed using SAS software version ۹.۴. RESULTS: The rate of dystocia, twinning, retention of fetal membranes, puerperal metritis and clinical endome-tritis, calf birth weight, and days to first service did not differ among the various AGD categories (P>۰.۰۵). However, proportion of male offspring was lower in the short AGD cows than intermediate and long AGD cows (P<۰.۰۵). Furthermore, the first service conception rate was greater in the intermediate anogenital distance group than short and long anogenital distance groups (P<۰.۰۵). CONCLUSIONS: In conclusion, the present study showed suboptimal first postpartum conception rate in the cows with minimal and maximal length of anogenital distance and indicated that this inferior fertility was not mediated through alteration in the rate of postpartum reproductive disorders

Keywords:

Anogenital distance , Dairy Cows , Dystocia , fertility , Uterine infections