Sexual maturity and fertility-related measures in young Nellore bulls receiving long-term dietary supplementation with rumen-protected polyunsaturated fatty acids

Abstract The objective of this study was to evaluate the effects of long-term supplementation with rumen-protected fatty acids (FA) on growth and reproductive parameters of young Nellore bulls in a grazing regime. Forty-eight young bulls were distributed into two groups: FA (supplemented with rumen-protected polyunsaturated FA); and control (control fat-free supplement). The animals were supplemented from 14.3 to 24.6 months of age and growth and reproductive parameters were evaluated at 28-day intervals. The semen was cryopreserved in the last collection and fresh and post-thaw semen samples were evaluated. Feeding FA did not affect (P > 0.05) growth, reproductive parameters (scrotal circumference, sperm concentration per mL of ejaculate, percentage of sperm defects, sperm quality and fertility in vitro ), or testicular ultrasonographic characteristics. However, thawed semen from bulls fed FA exhibited better quality (P  in vitro embryo production rates.