饲料中不同淀粉水平对中华绒螯蟹幼蟹生长、饲料利用的影响
EFFECT OF DIETARY STARCH LEVEL ON GROWTH, FEED UTILIZATION AND HEPATIC GLYCOGEN OF ERIOCHEIR SINENSIS
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摘要: 实验配制7种等氮(粗蛋白35%)、等脂(粗脂肪6%)的不同淀粉水平(4%、10%、16%、22%、28%、34%、40%)的饲料, 投喂中华绒螯蟹(Eriocheir sinensis)幼蟹初始均重(6.20.1) g 8周, 通过生长和生理指标评价中华绒螯蟹幼蟹对饲料碳水化合物的利用能力。为避免互相残杀, 河蟹采用静水单个养殖, 每种饲料40只河蟹。玉米淀粉作为实验饲料碳水化合物主要来源。实验结果表明: 饲料中34%-40%淀粉组的摄食率显著低于4%-16%组(P0.05)。随饲料中淀粉含量提高幼蟹的体重和壳长特定生长率也相应提高, 34%淀粉组体重特定生长率显著高于4%淀粉组(P0.05), 22%淀粉组的壳长特定生长率显著高于4%淀粉组(P0.05); 饲料中淀粉含量的增加显著提高了饲料效率, 且在40%淀粉组最高。饲料高淀粉可提高蛋白储积率, 蟹的肝体比在16%淀粉组最低, 而蜕壳率和成活率在该组最高。蟹体干物质、粗蛋白、粗脂肪和灰分在高饲料淀粉组较高。幼蟹胰蛋白酶活力在16%淀粉组最高(P0.05); 肝糖原含量随饲料淀粉水平升高呈线性(y=0.2268x+ 17.256, R2=0.9453, n=7, P0.05)上升。通过二次多项式回归可以得出河蟹获得最大特定生长率时饲料淀粉的含量为25.6%。Abstract: In order to investigate the utilization of dietary starch by Eriocheir sinensis,seven isonitrogenous (crude protein: 35%) and isolipid (crude lipid: 6%) diets that contained different starch levels (4%, 10%, 16%, 22%, 28%, 34% and 40%) were formulated. Different diets were fed to crabs for 8 weeks. In order to avoid cannibalism, 40 crabs were reared individually in 40 small plastic tanks (25 cm17 cm15 cm)with several holes on the bottom. The results showed that feeding rates of the crabs that were fed with 34%-40% dietary starch were significantly lower than those fed with 4%-16% dietary starch (P0.05). Dietary starch increased specific growth rates of body weight and carapace length. Specific growth rate of body weight reached to the highest at 34% dietary starch while specific growth rate of carapace length was the highest at 22% dietary starch(P0.05). Feed efficiency increased with increasing dietary starch. High dietary starch obtained higher protein retention. Hepatosomatic index of the crabs fed with 16% dietary starch was lower while molting frequency and survival werehigher. Crab body dry matter, protein, lipid and ash were higher at the group fed with higher dietary starch. Hepatopancreatic trypsin activity was higher at 16% dietary starch (P0.05). Liver glycogen content increased linearly with dietary starch (y=0.2268x + 17.256, R2=0.9453, n=7, P0.05). Quadratic regression between specific growth rate and dietary starch showed that optimal dietary starch content for maximum growth of juvenile mitten crab was 25.6%.