Age-related changes in scrotal circumference, testis size and sperm reserves in bulls of the tropically adapted Senepol breed
1993; Elsevier BV; Volume: 32; Issue: 3-4 Linguagem: Inglês
10.1016/0378-4320(93)90090-e
ISSN1873-2232
Autores Tópico(s)Animal Genetics and Reproduction
ResumoTesticular characteristics were measured in a random population of Senepol bulls representing three farms on St. Croix (17°N, 64°W), during a 5 year period. Bulls were maintained on native, tropical grass/legume pasture throughout all stages of development. Scrotal circumference (SC; 317 measurements, 267 bulls) increased in a curvilinear relationship (P < 0.001) with both age (r2 = 0.816) and body weight (r2 = 0.856) and reached a mean maximum SC of 42.4 cm at 6–7 years of age. There was a linear relationship (n=84; P<0.001) between SC and total testicular weight (r2=0.883), testis length (r2=0.800) and testis width (r2=0.969). Testicular weights and dimensions were highly correlated (P<0.001) with epididymal weights. Mean daily sperm production rate (14.1 × 109 spermatozoa g−1) did not differ between pubertal (n=5), postpubertal (n=5) and mature bulls (n = 5); however, total daily sperm production and epididymal reserves increased (P< 0.05) from 4.9 × 109 and 6.9 × 109 to 10.1 × 109 and 42.1 × 109 spermatozoa in pubertal and mature bulls, respectively. The data indicate that SC, testicular weight and sperm reserves of Senepol bulls more closely resemble those reported for Bos taurus than Bos indicus genotypes.
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