Walker S, Robison O W, Whisnant C S, Cassady J P
Department of Animal Science, North Carolina State University, Raleigh 27695-7621, USA.
J Anim Sci. 2004 Aug;82(8):2259-63. doi: 10.2527/2004.8282259x.
The objective of this study was to characterize correlated responses in testicular morphology and daily sperm production to divergent selection for testosterone production. Duroc boars from high and low lines (HTL and LTL, respectively) divergently selected over 10 generations for testosterone production in response to a GnRH challenge followed by random selection were used. Testicular tissues were sampled from all available males of generation 20 (HTL, n = 46; and LTL, n = 13). Volume densities for Leydig cells, seminiferous tubules, and Sertoli cells were estimated along with sperm production. The HTL boars had greater volume densities of Leydig cells than did LTL (P < 0.01). Volume density of seminiferous tubules tended to differ between lines (P < 0.07), but Sertoli cell volume densities did not differ (P < 0.27). Sperm production traits, adjusted for age, did not differ significantly between lines. Body, testicular, and epididymal weights were recorded for boars from HTL (n = 82) and LTL (n = 44) from generations 20 and 21. After adjustment for BW, average paired testicular weights for HTL and LTL were 417 and 457 g (P < 0.01), respectively. Epididymal weights, adjusted for BW, were heavier for HTL (P < 0.01) than for LTL. To demonstrate that the selection lines still differed for testosterone production, lines were evaluated in generation 21. Endogenous testosterone production of the HTL (n = 54) and LTL (n = 44) testosterone production line averaged 49.0 ng/mL and 27.8 ng/mL (P < 0.01), respectively. Plasma FSH concentrations did not differ between lines (P < 0.30). Selection for testosterone production in response to a GnRH challenge was an effective method of changing testosterone concentrations, testicular size, epididymal weight, and volume density of Leydig cells. However, daily sperm production per gram of testes was unchanged. Based on the results of this study, selection for testosterone production is not recommended as a method of increasing sperm production in pigs.
本研究的目的是描述睾丸形态和每日精子生成量对睾酮生成差异选择的相关反应。使用了来自高、低系（分别为HTL和LTL）的杜洛克公猪，这两个系在10代中针对GnRH刺激后的睾酮生成进行了差异选择，随后进行随机选择。从第20代所有可用雄性（HTL，n = 46；LTL，n = 13）采集睾丸组织。估计了睾丸间质细胞、生精小管和支持细胞的体积密度以及精子生成量。HTL公猪的睾丸间质细胞体积密度高于LTL公猪（P < 0.01）。生精小管的体积密度在品系间有差异趋势（P < 0.07），但支持细胞的体积密度无差异（P < 0.27）。调整年龄后的精子生成性状在品系间无显著差异。记录了第20代和第21代HTL（n = 82）和LTL（n = 44）公猪的体重、睾丸和附睾重量。调整体重后，HTL和LTL的平均双侧睾丸重量分别为417克和457克（P < 0.01）。调整体重后的附睾重量，HTL比LTL重（P < 0.01）。为证明选择系在睾酮生成方面仍存在差异，在第21代对品系进行了评估。HTL（n = 54）和LTL（n = 44）睾酮生成系的内源性睾酮生成平均分别为49.0 ng/mL和27.8 ng/mL（P < 0.01）。血浆促卵泡素浓度在品系间无差异（P < 0.30）。针对GnRH刺激的睾酮生成选择是改变睾酮浓度、睾丸大小、附睾重量和睾丸间质细胞体积密度的有效方法。然而，每克睾丸的每日精子生成量未改变。基于本研究结果，不建议将睾酮生成选择作为增加猪精子生成量的方法。
