Walkden-Brown S W, Restall B J, Taylor W A
Department of Agriculture, University of Queensland, Australia.
Reprod Fertil Dev. 1994;6(6):727-36. doi: 10.1071/rd9940727.
Each month, for 15 months, the testes and epididymides were recovered from five Australian cashmere bucks selected at random from a group of mature bucks (initial n = 116) at pasture (location 29 degrees S, 153 degrees E). The extent of seasonal change in testicular and epididymal sperm reserves was determined and indirect methods for predicting these reserves were developed. 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, determined by homogenization, showed a very similar seasonal pattern, ranging from 13.8 x 10(9) in September to 36.2 x 10(9) in March. 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 (R2 = 0.72, P < 0.001), the elongated spermatid content of testicular parenchyma (mean, 127 x 10(6) g-1) exhibited significant seasonal variation with elevated values between February and June, suggestive of an increase in the efficiency of spermatogenesis. Daily sperm production, calculated by means of a spermatogenic time divisor for sheep, ranged from 2.76 x 10(9) in September to 7.23 x 10(9) in February. Scrotal circumference, scrotal volume and testicular length x diameter2 were identified as accurate predictors of testicular weight (R2 > or = 0.87) and sperm content (R2 > or = 0.70). The results demonstrate that: (a) 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 (b) indirect measures of testicular size are good predictors of testicular elongated sperm content. When the correct spermatogenic time divisor for goats is determined, such indirect measures may be used to predict daily sperm production.
在15个月的时间里，每月从一群在牧场（南纬29度，东经153度）放牧的成年公羊（初始数量n = 116只）中随机挑选5只澳大利亚绒山羊公羊，采集其睾丸和附睾。确定了睾丸和附睾精子储备的季节性变化程度，并开发了预测这些储备的间接方法。成对睾丸重量呈现出明显的季节性变化，从8月的137克到2月的269克。通过匀浆法测定的睾丸总延长型精子细胞含量呈现出非常相似的季节性模式，从9月的13.8×10⁹个到3月的36.2×10⁹个。成对附睾重量和精子含量也观察到了类似时间的季节性变化。虽然睾丸总精子细胞含量的变化在很大程度上是睾丸重量变化的结果（R² = 0.72，P < 0.001），但睾丸实质的延长型精子细胞含量（平均值为127×10⁶个/克）在2月至6月间呈现出显著的季节性变化，且数值升高，这表明精子发生效率有所提高。通过绵羊精子发生时间除数计算得出的每日精子产量，从9月的2.76×10⁹个到2月的7.23×10⁹个不等。阴囊周长、阴囊容积以及睾丸长度×直径²被确定为睾丸重量（R²≥0.87）和精子含量（R²≥0.70）的准确预测指标。结果表明：（a）绒山羊公羊的精子发生呈现出相当大的季节性变化，主要与睾丸质量的变化有关，但也与精子发生效率的变化有关；（b）睾丸大小的间接测量方法是睾丸延长型精子含量的良好预测指标。当确定了山羊正确的精子发生时间除数后，这种间接测量方法可用于预测每日精子产量。
