161 Anti-Müllerian hormone concentration as a predictor of puberty in male Brahman and Simmental bulls

This study aimed to investigate whether the pre-pubertal scrotal circumference (SC) and anti-Müllerian hormone (AMH) concentration indicate sexual precocity in Brahman and Simmental bulls using a total of 53 bulls (Brahman, n = 27; Simmental, n = 26). The SC was measured at three periods: pre-puberty (Brahman 19.99 ± 0.20 months and 9.13 ± 0.17 months in Simmental), puberty (Brahman 21.42 ± 0.20 months and 18.26 ± 0.17 months in Simmental), and post-puberty (Brahman 33.34 ± 0.55 months and Simmentals 24.07 ± 0.17 months). The AMH concentration was measured at pre-puberty, and the classes were formed based on the frequency distribution of AMH concentrations: low AMH <2.28 ng mL⁻¹ and high AMH ≥2.28 ng mL⁻¹. The SC was negatively correlated with the percentage of total defects (r = −0.5957; P = 0.0246) and positively correlated with the percentage of normal sperm (r = 0.595; P = 0.0265). There was a high correlation between the SC assessment periods (pre-puberty, puberty, and sexual maturity) in both breeds (Brahman: r = 0.8776; P = 0.0005; Simmental: 0.7483; P = 0.0002), demonstrating the high repeatability of the measurement. The SC at puberty was higher (P = 0.0002) in animals of the low AMH class (34.78 ± 0.78 cm) than in those of the high AMH class (32.47 ± 0.42 cm). Males classified as having low AMH concentration had better results on andrological assessment (vigor: 3.92 ± 0.20; sperm mass movement (turbulence): 2.63 ± 0.19; progressive motility: 77.55 ± 3.80) than those classified as having high AMH concentration (vigor: 3.33 ± 0.19; turbulence: 2.06 ± 0.19; progressive motility: 65.14 ± 3.79). It can be concluded that AMH concentration correlated with SC at pre-puberty is a good predictor of sexual precocity in Brahman and Simmental bulls.