D'Occhio M J, Schanbacher B D, Kinder J E
Biol Reprod. 1984 Jun;30(5):1039-54. doi: 10.1095/biolreprod30.5.1039.
Mature rams of Polled Dorset, Finnish Landrace, Rambouillet and Suffolk breeding were maintained in a temperature-controlled environment and exposed to two consecutive cycles of short (8L:16D) followed by long (16L:8D) days. Serum hormone concentrations were determined in weekly samples and in 24-h profiles characterized at the end of each lighting schedule (i.e., 12, 24, 36 and 48 weeks). In all four breeds, the pituitary-testicular axis was more active during short days as compared with long days and the magnitudes of changes in serum luteinizing hormone (LH), follicle-stimulating hormone (FSH) and testosterone concentrations were greater for the two most seasonal breeds, Finnish Landrace and Suffolks. In comparison to other breeds, Finnish Landrace rams had significantly (P less than 0.05) higher mean LH levels, showed the greatest number of LH peaks/24 h, and had the highest mean testosterone levels at the end of both periods of short days, while Rambouillet rams had significantly (P less than 0.05) lower testosterone. Rambouillets also showed the smallest changes in pulsatile LH and testosterone secretion and displayed the least number of LH peaks/24 h following short days. Serum FSH levels were significantly (P less than 0.05) higher in Finnish Landrace and Suffolk rams than in Polled Dorsets and Rambouillets after 12 weeks of short days. Breed differences in serum LH, FSH and testosterone were not apparent following long days. Prolactin levels in Rambouillet rams were significantly (P less than 0.05) lower than in the other breeds following both periods of long days. These results indicate that breed differences exist in mature rams with regard to hormone secretory profiles. Breed differences in serum gonadotropin and testosterone are only apparent during short days when the hypothalamo-pituitary-testicular axis in rams is considered most active. Likewise, breed differences in prolactin are noticeable only during long days when secretion of this hormone is enhanced. Breed differences in LH, FSH and testosterone secretion in rams during short days might be related to seasonality of mating and/or fecundity of breed types.
将无角陶赛特羊、芬兰长白猪、兰布莱绵羊和萨福克羊品种的成年公羊饲养在温度可控的环境中，使其经历两个连续的短日照（8小时光照：16小时黑暗）周期，随后是长日照（16小时光照：8小时黑暗）周期。每周采集样本测定血清激素浓度，并在每个光照周期结束时（即12、24、36和48周）对24小时激素变化情况进行分析。在所有四个品种中，与长日照相比，短日照期间垂体 - 睾丸轴更为活跃，对于两个季节性最强的品种——芬兰长白猪和萨福克羊，血清促黄体生成素（LH）、促卵泡生成素（FSH）和睾酮浓度的变化幅度更大。与其他品种相比，芬兰长白猪公羊在两个短日照周期结束时，平均LH水平显著更高（P < 0.05），每24小时出现的LH峰值数量最多，平均睾酮水平也最高，而兰布莱绵羊公羊的睾酮水平则显著更低（P < 0.05）。兰布莱绵羊在短日照后LH和睾酮脉冲分泌的变化也最小，每24小时出现的LH峰值数量最少。短日照12周后，芬兰长白猪和萨福克羊公羊的血清FSH水平显著高于无角陶赛特羊和兰布莱绵羊（P < 0.05）。长日照后，血清LH、FSH和睾酮的品种差异不明显。两个长日照周期后，兰布莱绵羊公羊的催乳素水平显著低于其他品种（P < 0.05）。这些结果表明，成年公羊在激素分泌模式方面存在品种差异。血清促性腺激素和睾酮的品种差异仅在短日照期间明显，此时公羊的下丘脑 - 垂体 - 睾丸轴被认为最为活跃。同样，催乳素的品种差异仅在长日照期间明显，此时该激素的分泌会增强。公羊在短日照期间LH、FSH和睾酮分泌的品种差异可能与交配的季节性和/或品种类型的繁殖力有关。
