Testicular and epididymal sperm content in grazing cashmere bucks: seasonal variation and prediction from measurements in vivo [goats]
1994
Walkden-Brown, S.W. (Queensland Univ., St Lucia (Australia). Dept. of Agriculture) | Restall, B.J. | Taylor, W.A. (New South Wales Agriculture, Wollongbar (Australia). Wollongbar Agricultural Inst.)
Each month, for 15 months, the testes and epididymides were recovered from 5 Australian cashmere bucks selected at random from a group of nature bucks at pasture. Paired testicular weight exhibited clear seasonal variation from 137 g in August to 269 g in February. The total elongated spermatid content of the testes showed a very similar seasonal pattern. Seasonal changes of similar timing were observed for paired epididymal weight and sperm content. Although changes in total testicular spermatid content were largely the result of change in testicular weight, the elongated spermatid content of testicular parenchyma exhibited significant seasonal variation with elevated values between February and June, suggestive of an increase in the efficiency of spermatogenesis. Scrotal circumference, scrotal volume and testicular length x diameter were identified as accurate predictors of testicular weight and sperm content. The results demonstrate: that cashmere bucks exhibit considerable seasonal variation in spermatogenesis associated primarily with changes in testicular mass but also with changes in the efficiency of spermatogenesis; and that indirect measures of testicular size are good predictors of testicular elongated sperm content. When the correct spermatogenic time divisor for goats is determined, daily sperm production may be predicted.
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