Anti-Mullerian hormone and its relationship to ovulation response and fertility in timed AI Bos indicus heifers.

This study evaluated the association between plasma anti-Mullerian hormone (AMH) concentration and fertility in Nelore (Bos indicus) heifers submitted to timed artificial insemination (TAI). At the onset of the synchronization protocol, heifers (n = 289) received a subcutaneous P4 ear implant (3 mg) and 2 mg of oestradiol benzoate. Eight days later, the P4 implant was removed and 0.5 mg of oestradiol cypionate, prostaglandin (0.265 mg, i.m.) and equine chorionic gonadotropin (300 UI, i.m.) was administered, and TAI was performed 48 hr after ear implant removal. Ovarian ultrasound evaluations were performed to measure number of ovarian follicles, dominant follicle size and ovulation response. Pregnancy diagnosis was performed by ultrasound 30 days after AI. Heifers with greater circulating AMH had more antral follicles, a smaller dominant follicle near timed ovulation and lower ovulation response to the timed AI protocol compared to heifers with lower circulating AMH. Although AMH and pregnancy outcome had a quadratic-shaped pattern, AMH was not significantly associated with fertility. In conclusion, heifers with lower AMH had larger follicles towards the end of the synchronization protocol and greater ovulation responses, whereas greater circulating AMH was unrelated to conception success.

Effects of inbreeding on growth and slaughter trails of rabbits / Efeito da endogamia em características de crescimento e abate de coelhos

Data from 1,512 Californian and 1,370 New Zealand White rabbits were analyzed by least squares procedures to study the effect of inbreeding of individuals, a covariate in the mathematical model, on body weights from weaning to slaughter and dressing percentage. Both linear and quadratic regression coefficients of inbreeding of rabbits were important for weights at several ages. Inbreeding of rabbits did not affect their performances at weaning and 5 weeks of age, but had an important effect on body weights measured from 6 to 11 weeks of age, with increases of performance from F=0 up to F=10% and reductions after that level. The effect of inbreeding was small on the weights observed at slaughter, and the trend was of reduction of weights when F increased. The same trend was observed for dressing percentage.

Os pesos individuais semanais da desmama ao abate de 2.882 coelhos, sendo 1.512 da raça Califórnia e 1.370 da raça Nova Zelândia Branca foram analisados pelo método dos quadrados mínimos para verificação dos efeitos da endogamia, uma covariável no modelo matemático, no desempenho desses animais. Tanto os efeitos lineares quanto quadráticos da endogamia dos coelhos foram importantes para pesos individuais a diversas idades. A endogamia dos coelhos não afetou seu desempenho à desmama (realizada em média aos 28 dias) e nem às cinco semanas de idade, mas afetou significativamente os pesos corporais de 6 a 11 semanas, com aumentos de pesos para endogamia variando de 0 a 10% e diminuições do desempenho após este nível. Nas características de carcaça e abate, o efeito foi pequeno, com uma tendência geral de decréscimo com o aumento do coeficiente de endogamia, o mesmo sendo verificado com o rendimento de carcaça. Estes resultados demonstram a importância do controle dos níveis de endogamia em coelhos, pois, mesmo quando mantidos abaixo dos 10%, podem afetar significativamente o desempenho produtivo.