Andrological characteristics of Gyr (bos indicus) bulls]

Gyr bulls were ranked regarding their reproductive potential, following evaluations through the scorebased andrological classification system ( ACP). For the examinations, three animal age groups were considered: 18 to 24 month- old ( G1, n= 33), 25 to 31 month- old ( G2, n= 24), and 32 to 38 month- old ( G3, n= 12). Scrotal circumference was lower in G1, as compared to G2 and G3 ( P < 0.05). Percent motility and vigor were not affected by the age groups. Percent rates of major and total defects were higher ( P < 0.05) in G1 than in G2 or G3. No significant differences were observed when G2 and G3 were compared. Regarding ACP data, G1, G2 and G3 yielded, respectively, 25.7, 58.3 and 61.5% of adequate breeders; 11.4, 20.8 and 15.4% of bulls with undefined breeding capacity, and 57.1, 12.5 and 15.4% of inapt breeders or immature animals. Age group affected scrotal circumference and major and total defects, but did not influence motility or vigor. The highest proportion of adequate breeders was obtained with 24- month- old bulls and older.