Growth and testicular development in Bunaji bulls
1981
Osinowo, O.A. (National Animal Production Research Inst., Shika Zaria (Nigeria)) | Molokwu, E.C.I. | Osori, D.I.K. (Ahmadu Bello Univ., Zaria (Nigeria). Faculty of Veterinary Medicine)
The relation of testicular development to body growth was investigated in 20 Bunaji bull calves over a period of 10 months. For the entire period highly significant correlations existed between age and body weight (r=0.87), age and heartgirth (r=0.84), heartgirth (x) and body weight (y)(r=0.95). The regression equation between the latter pair of variables was y=-288.68 + 3.5x. The correlation coefficients between scrotal circumference (SC) and age, SC and body weight, and SC and heartgirth were 0.88, 0.88 and 0.86 respectively. The relationship between SC and paired testes weight (TW) when the bulls were slaughtered was described by the regression equation TW=-408.57 + 25.6 (SC), r=0.94. Testicular size (weight or volume) closely paralleled testicular development (seminiferous tubule diameter or gonadal sperm/spermatid reserve). Spermatogenesis had commenced in the bulls by 13 months (age of youngest bull at slaughter). However, consistently large gonadal and epididymal sperm reserves were only found in bulls aged 17 months and above
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