Graduate Institute of Agriculture, National Chiayi University, Chiayi, Taiwan.
Poult Sci. 2010 Mar;89(3):558-63. doi: 10.3382/ps.2009-00429.
This study examined the effects of caponization and different exogenous androgen implantations on the growth performance and muscle characteristics of caponized male chickens. Male Single Comb White Leghorn chickens were caponized at 12 wk of age and selected at 16 wk of age for a 10-wk feeding period. Sixteen intact males and caponized (capon) chickens each were assigned for trial 1. Sixteen sham-operated male chickens (sham) and 64 capons were selected for trial 2, in which capons were randomly divided into cholesterol (CHOL), testosterone (TES), 5alpha-dihydrotestosterone (5alpha-DHT), or 19-nortestosterone (19-NorT) implantation at 16, 20, and 24 wk of age, with feeding to 26 wk of age. The result from trial 1 showed that caponization improved BW gain and feed conversion rate (P < 0.05) and decreased the comb length, height, and weight (P < 0.05). Breast muscle weight and gastrointestinal tract weight were higher in capons compared with intact males (P < 0.05). In trial 2, CHOL implantation decreased relative thigh muscle weight compared with the sham (P < 0.05), and only 19-NorT implantation increased relative thigh muscle weight to the compatible level with the sham (P > 0.05). 19-Nortestosterone and 5alpha-DHT implantations showed lower crude fat in the pectoral major muscle than CHOL (P < 0.05) and reached a compatible level with the sham (P > 0.05). All androgen implantation groups showed higher myofibrillar ATPase activity than CHOL (P < 0.05), and 19-NorT and 5alpha-DHT had the highest level (P < 0.05). Only 19-NorT implantation demonstrated higher shear value than CHOL (P < 0.05) to the compatible level with the sham (P > 0.05). Androgen implantation increased emulsifying capacity compared with CHOL (P < 0.05) and reached a compatible level with the sham (P > 0.05). Caponization decreased the blood TES concentration in male chickens, leading to changes in growth performance and muscle characteristics. After different androgen implantations in capons, 19-NorT showed the most effective results in increasing muscle quality and quantity, followed by the 5alpha-DHT and TES.
本研究探讨了去势和不同外源性雄激素植入对去势公鸡生长性能和肌肉特性的影响。12 周龄的雄性单冠白来航鸡去势，16 周龄时选择进行 10 周的饲养试验。试验 1 中，每组 16 只公鸡，其中 8 只为去势公鸡（capon），16 只为未去势公鸡（intact）。试验 2 中，每组 16 只假手术公鸡（sham），64 只为去势公鸡，其中 32 只为胆固醇（CHOL）、32 只为睾丸酮（TES）、32 只为 5α-二氢睾丸酮（5α-DHT）或 19-去甲睾丸酮（19-NorT）植入组，分别于 16、20 和 24 周龄时植入，26 周龄时结束饲养。试验 1 结果表明，去势可提高公鸡的体重增重和饲料转化率（P<0.05），降低鸡冠长度、高度和重量（P<0.05）。与未去势公鸡相比，去势公鸡的胸肌重量和胃肠道重量更高（P<0.05）。在试验 2 中，与假手术组相比，CHOL 植入组的大腿肌肉相对重量降低（P<0.05），仅 19-NorT 植入组的大腿肌肉相对重量增加到与假手术组相匹配的水平（P>0.05）。与 CHOL 相比，19-NorT 和 5α-DHT 植入组的胸大肌粗脂肪含量更低（P<0.05），并达到与假手术组相匹配的水平（P>0.05）。所有雄激素植入组的肌纤维 ATP 酶活性均高于 CHOL（P<0.05），19-NorT 和 5α-DHT 组的活性最高（P<0.05）。只有 19-NorT 植入组的剪切值高于 CHOL（P<0.05），达到与假手术组相匹配的水平（P>0.05）。与 CHOL 相比，雄激素植入可提高乳化能力（P<0.05），并达到与假手术组相匹配的水平（P>0.05）。去势降低了公鸡血液中的 TES 浓度，导致生长性能和肌肉特性发生变化。在去势公鸡中进行不同的雄激素植入后，19-NorT 对增加肌肉质量和数量的效果最显著，其次是 5α-DHT 和 TES。
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