Comparative analysis of serum anti-Müllerian hormone (AMH) levels in sheep: the role of genetic background and physiological status

Abstract. Anti-Müllerian hormone (AMH) serves as a reliable marker for ovarian reserve and reproductive potential in many species. However, there is limited information available on the factors influencing AMH levels in sheep. Thus, this study aimed to evaluate the effects of breed, age, body condition score (BCS), and parity on serum AMH concentrations in four commercial sheep breeds: Lacaune, Assaf, Île de France, and Merino. A total of 120 clinically healthy ewes aged between 19 and 34.5 months were included, with equal representation across breeds and lactation stages. AMH levels were measured using standardized laboratory techniques. Significant differences in serum AMH concentrations were observed among breeds (p<0.001). Île de France and Merino breeds exhibited significantly higher mean AMH levels (479.0 and 391.0 pg mL−1 respectively) compared to Lacaune and Assaf breeds (261.3 and 205.3 pg mL−1, respectively), suggesting a larger ovarian follicular reserve in these breeds. The range of AMH values was widest in Île de France sheep, indicating considerable intra-breed variability. No statistically significant effects of age, BCS, or parity on serum AMH concentrations were detected (p>0.05). These findings highlight the predominant influence of genetic factors on ovarian reserve in sheep as reflected by serum AMH levels. The elevated AMH concentrations in Île de France and Merino breeds may be linked to superior reproductive potential. Understanding breed-specific variations in AMH could support selective breeding programs aimed at enhancing sheep reproductive efficiency and productivity.