RESUMO
Decreased semen quality and fertility rate is a common feature in broiler breeder roosters. This decrease is associated with dysfunction of Sertoli cells and defective spermatogenesis. Guanidinoacetic acid (GAA), as a precursor of creatine, plays an important role in the proper functioning of Sertoli cells and energy metabolism in sperm. Twenty, 29-wk-old broiler breeder roosters (Ross 308) were randomly allotted to 4 treatment groups and fed diets supplemented with different levels of GAA, including 0 (GAA-0), 600 (GAA-600), 1200 (GAA-1200), and 1800 (GAA-1800) mg GAA/kg of diet for 26 successive weeks. During a 24-wk period, the seminal characteristics were weekly evaluated. At the end of experiment, sperm penetration and fertility rates were determined, using 68 artificially inseminated age-matched broiler breeder hens of the same strain (for 2 weeks). Semen concentration (P = 0.003), total sperm number (P = 0.005) and sperm forward motility (P = 0.01) were increased by GAA-1200 group. Also, sperm plasma membrane functionality was marginally affected (P = 0.06) in roosters received all levels of GAA. Sperm abnormality and plasma membrane integrity were not affected by dietary GAA. The highest number of sperm penetration holes was recorded for the GAA-1200 group (P = 0.08). Interestingly, fertility rate was increased by the feeding of all levels of GAA (P = 0.01). In conclusion, dietary GAA was associated with improvement in most of the rooster's seminal characteristics and fertility rate, suggesting a potential for using GAA to attenuate the age-related sub-fertility in commercial broiler breeder roosters.