Anti-Müllerian Hormone as a Marker for Castration Status and Fertility in Bulls and Oxen

Anti-Müllerian hormone (AMH) has been established as an indicator of castration status and fertility in several species. However, its applicability in postpubertal bulls and oxen has not yet been thoroughly investigated. This study examined 73 bulls aged between 12 and 107 months and 37 oxen older than 12 months. Blood serum samples were collected from all animals for AMH measurement using a commercial chemiluminescent immunoassay. Additionally, testosterone concentrations were assessed in 32 oxen and 71 bulls using mass spectrometry. In bulls, correlations between AMH levels and sperm concentration, motility and morphology were analysed. The AMH concentration in oxen (median: 0.01 ng/mL) was significantly lower (p < 0.001) than in bulls (median: 4.69 ng/mL). While reduced sperm motility had a significant impact on the AMH concentration (p = 0.02), this was not the case for sperm morphology (p = 0.31). In addition, in bulls with normal semen parameters, AMH concentration showed a negative correlation with age (p = 0.01). In conclusion, AMH (≤ 0.01 ng/mL) serves as a reliable marker for distinguishing oxen from bulls, even in older animals. To our knowledge, this is the first study evaluating AMH as a fertility-associated biomarker in postpubertal bulls.