Utilização de características indicadoras de fertilidade na predição do potencial reprodutivo de fêmeas e machos Bos taurus e Bos indicus

Abstract

Were evaluated the influence of serum concentrations of the Anti-Mullerian hormone on the fertility of females and the detection of precocious puberty in males of different genetic groups (Bos taurus taurus and Bos taurus indicus). In addition, the size and functionality of reproductive structures (ovaries, testicles, vulva) were measured in order to verify possible relationships with fertility and precocity measures. In females, classes of vulvar width (small VWC ≤86mm and large VWC: >86mm), ovarian size score (small, medium and large), class of AMH (low: ≤0.81ng/mL and high: >0,81ng/mL) and AFC were determined in Brahman, Angus and Simental females. Reproductive efficiency indexes taken from the property database were related to the measurements taken. In males (Brahman and Simental), scrotal circumference (SC) was measured in three periods (pre-puberty, puberty and sexual maturity) using a flexible tape measure. AMH concentration was measured at pre puberty (9 months for Simental and 20 months for Brahman) and the animals were classified as low AMH (<2,28 ng/mL) and high AMH (≥2,28 ng/mL). The andrological evaluation was performed at puberty and sexual maturity with the objective of correlating the physical and morphological parameters of the semen with the measurements made. In zebu females compared to taurines, AFC (36.30±1.34 vs. 22.09±1.67), VWC (106.94±15.83 vs. 69.78±14.11 mm) and AMH (1.18±0.07 vs. 0.42±0.05 ng/mL) were higher. AFC (36.10±1.90 vs 22.78±1.64), AMH (1.17±0.07 vs. 0.48±0.007 ng/mL) and viable oocytes (18.86±1.76 vs 10.15±1.49) were higher (P<0.05) in the large VWC compared to the small VWC, respectively. The effects of VWC, AMH and reproductive efficiency indexes were not observed (P>0.05). In males, the EC was negatively correlated with the percentage of total defects (r=-0.5957; P=0.0246) and positively with the percentage of normal spermatozoa (r=0.595; P=0.0265). SC was higher (P = 0.0002) for animals of the low AMH class (34.78±78) compared to high (32.47±0.42). Males classified as low AMH obtained better (P<0.05) results (vigor: 3.92±0.20, swirling: 2.63±0.19, progressive motility: 77.55±3.80) in the andrological exam when compared to those with high AMH (vigor: 3.33±0.19, swirling: 2.06±0.19, progressive motility: 65.14±3.79). It was concluded that, in Brahman, Angus and Simental females, vulvar width was a good predictor of AFC and AMH concentrations in both genetic groups. The markers studied had a positive effect on the number of viable oocytes, therefore, they proved viable for donor selection under the conditions of this experiment. In males, the concentration of AMH associated with EC in the pre-puberty period were good predictors of sexual precocity in bulls of the Brahman and Simental breeds.