不同饵料蛋糖比对草鱼幼鱼生长性能、体组成和消化酶活性

摘要：【目的】研究不同蛋糖比對草鱼幼鱼生长性能、体组成和肠道消化酶活性的影响，为草鱼营养需求研究及饵料配制提供参考依据。【方法】采用单因素设计，以饵料蛋糖比为影响因素，共配制6组等脂等能饵料，对应的蛋糖比值分别为2.00、1.50、1.14、0.88、0.67和0.50。草鱼幼鱼饲养于室内循环养殖系统中，日投饵3次，试验周期8周。【结果】蛋糖比对草鱼幼鱼存活率无显著影响（P>0.05，下同）；末体重、增重率和特定生长率受饵料蛋糖比影响显著（P<0.05，下同），均随蛋糖比降低呈先升高后降低的变化趋势，在蛋糖比为0.88时达最高值；饵料系数同样受蛋糖比影响显著，且在蛋糖比为0.88时最低（1.72）。随着饵料蛋糖比的降低，草鱼幼鱼蛋白效率比、氮保留率、脏体比、肝体比和腹脂率均显著升高，但对全鱼、胴体的蛋白和灰分含量无显著影响。全鱼水分含量随饵料蛋糖比的降低显著降低，而脂肪含量显著升高；胴体水分和脂肪含量及肝脏脂肪含量的变化趋势与全鱼一致。肠道蛋白酶和淀粉酶活性随着饵料蛋糖比降低呈先升高后降低的变化趋势，脂肪酶活性则显著升高。【结论】草鱼幼鱼饵料中添加适量糖可节约蛋白质，且适宜蛋白质和糖水平分别为30.61%和29.54%，最适蛋糖比为1.04；过高的饵料糖水平能显著增加草鱼幼鱼内脏器官的相对重量，促进体脂过度沉积和糖原合成。

关键词： 草鱼；饵料；蛋糖比；生长性能；体组成；消化酶活性

中图分类号： S963.16 文献标志码：A 文章编号：2095-1191（2016）05-0753-06

Abstract：【Objective】The present experiment was conducted to investigate effects of dietary protein to carbohydrate （P/CHO） ratio on growth performance， body composition and digestive enzymes activities of juvenile grass carp（Ctenopharyngodon idella）， in order to provide reference basis for nutritional requirement of grass carp and its feed preparation.【Method】According to single-factor design， the dietary P/CHO ratio was used as influencing factor. Six isolipidic and isoenergetic feed were formulated， with various dietary P/CHO ratios（2.00， 1.50， 1.14， 0.88， 0.67 and 0.50）. Fish were raised in several indoor aquarium tanks， and fed 3 times daily for 8 weeks. 【Result】The results showed that， the dietary P/CHO ratio had no significant effect on survival rate（P>0.05， the same below）. However， the dietary P/CHO ratio had significant effect on final body weight， weight gain（WG） and specific growth rate（SGR）（P<0.05， the same below）， and those indexes were first increased and then decreased with decreases of P/CHO ratio， and up to the highest values at P/CHO ratio of 0.88， respectively. Likewise， the feed conversion rate（FCR） was affected significantly by P/CHO ratio， and the lowest FCR（1.72） was found at dietary P/CHO ratio of 0.88. The protein efficiency ratio（PER）， nitrogen retention efficiency（NRE）， viscerosomatic index（VSI）， hepatosomatic index（HIS） and intraperitoneal fat ratio（IPF） all were increased significantly with decreasing dietary P/CHO ratios. However， P/CHO ratio had no significant effect on whole-body and carcass protein and ash content. With decreasing dietary P/CHO ratios， whole-body moisture decreased significantly， while lipid content icreased significantly. The similar variation trends were also found in carcass moisture and lipid contents as well as liver lipid content. In addition， intestine protease and amylase activities increased first and then decreased with decreasing dietary P/CHO ratios， but lipase activities increased significantly. 【Conclusion】An increase in dietary carbohydrate has a protein-sparing effect， and the optimal dietary protein and carbohydrate contents for juvenile grass carp are 30.61% and 29.54%， respectively， with optimum dietary P/CHO ratio of 1.04. However， the excessive carbohydrate can increase weight of internal organs， and promote fatty deposits and glycogen synthesis.