Evidence for quadratic association between serum anti-Müllerian hormone (AMH) concentration and fertility in dairy cows

ABSTRACT In cattle, results of some but not other studies indicated there has been an association of circulating anti-Mullerian hormone (AMH) concentration with reproductive variables. Considering the inconsistency in results among previous studies, there was evaluation of associations between circulating AMH and reproductive performance in dairy cows, and to this end, the prevailing data of serum AMH concentration and reproductive variables were used (n = 172). Preliminarily, association of AMH concentration with reproductive indices were analyzed using linear and quadratic models. Subsequently, cows were categorized based on AMH concentrations in four equal quartiles, including cows with the least (Q1; n = 43), moderately lesser (Q2; n = 43), moderately greater (Q3; n = 43) and greatest (Q4; n = 43) AMH concentrations, and reproductive variables were compared among the respective AMH quartiles. Initially, assessments indicated reproductive variables were not linearly associated with serum AMH (P >  0.05); however, for all reproductive variables except days to first breeding service (DFS) there was a quadratic association with serum AMH (P