Bielli A, Pedrana G, Gastel M T, Castrillejo A, Moraña A, Lundeheim N, Forsberg M, Rodriguez-Martinez H
Department of Anatomy and Histology, Centre for Reproductive Biology, Swedish University of Agricultural Sciences (SLU), Uppsala.
Anim Reprod Sci. 1999 Jun 28;56(2):93-105. doi: 10.1016/s0378-4320(99)00027-5.
The present study was conducted: (a) to determine the degree of seasonal variation in testis stereology in Corriedale rams between autumn and winter; (b) to test the hypothesis that testis stereology of Corriedale rams grazing native pastures during autumn and winter would differ from those of Corriedale rams grazing sown pastures and supplemented with grain during the same period; and (c) to determine whether Sertoli cell numbers differ in adult rams between the breeding season (autumn) and the following non-breeding season (winter). Twenty experimental animals were studied. Six rams (autumn control group, C-A) that had been grazing on native pasture (stocking rate = 2-3 animals ha(-1)) were castrated at the beginning of the experiment (March, early autumn). Seven rams (winter control group, C-W) continued to graze on native pasture at the same stocking rate until the end of the experiment (August, late winter). Another seven rams (treated group, T) grazed on improved pasture (stocking rate = 1-2 animals ha(-1)) and were supplemented with 1 kg grain ram(-1) day(-1) until the end of the experiment. Live weight, scrotal circumference, serum testosterone concentration and selected testicular stereological parameters were measured. The treatment did not impede the winter reduction in testicular activity and reduced its magnitude slightly (group T) compared with controls (group C-W). Sertoli cell numbers were higher in autumn (group C-A) than in winter, both on native (group C-W) and sown pastures (group T). Diminishing Sertoli cell numbers between autumn and the following winter suggest the occurrence of that Sertoli cell death during this period. The results indicate that, although the reproductive activity of Corriedale rams is moderately seasonal, a restricted change in grazing and grain supplementation can only modify it to a limited extent.
(a) 确定秋季至冬季期间考力代公羊睾丸组织形态学的季节性变化程度；(b) 检验以下假设：秋季和冬季在天然草场上放牧的考力代公羊的睾丸组织形态学与同期在人工草场上放牧并补饲谷物的考力代公羊不同；(c) 确定成年公羊在繁殖季节（秋季）和随后的非繁殖季节（冬季）之间支持细胞数量是否存在差异。对20只实验动物进行了研究。6只公羊（秋季对照组，C-A）在实验开始时（3月，初秋）被阉割，它们一直在天然草场上放牧（载畜率 = 2 - 3只/公顷）。7只公羊（冬季对照组，C-W）以相同载畜率继续在天然草场上放牧，直至实验结束（8月，冬末）。另外7只公羊（处理组，T）在改良草场上放牧（载畜率 = 1 - 2只/公顷），并每天每只补饲1千克谷物，直至实验结束。测量了体重、阴囊周长、血清睾酮浓度以及选定的睾丸组织形态学参数。与对照组（C-W组）相比，处理措施并未阻碍睾丸活动在冬季的下降，只是使其下降幅度略有减小（T组）。在秋季（C-A组），无论是在天然草场（C-W组）还是人工草场（T组），支持细胞数量都高于冬季。秋季至次年冬季支持细胞数量减少表明在此期间发生了支持细胞死亡。结果表明，尽管考力代公羊的繁殖活动具有一定的季节性，但放牧和补饲谷物的有限变化只能在一定程度上对其进行改变。
