饲料糖水平对点篮子鱼生长性能的影响

以鱼粉为蛋白源,糊精为糖源,配制等蛋白质(含量为35%)、等能量糖水平分别为5%,10%,15%,20%,25%,35%(标号分别为T1、T2、T3、T4、T5、T6)的6组配合饲料,对点篮子鱼(Siganus guttatus)投喂56d,研究了饲料中糖水平变化对体重为34.45±10.61 g点篮子鱼生长、体成分和生物学指标的影响。结果显示,随着饲料糖水平的增加,点篮子鱼的摄食率和生长率呈先增加后降低的趋势,特定生长率(SGR)与饲料糖水平之间适宜的二次方程:y=0.455 1+0.012 5x-0.000 3x2(R2=0.913 7),点篮子鱼饲料中糖的最适添加水平为20.83%;饲料系数(FCR)和肌肉中粗脂肪含量与饲料中糖水平变化成正相关;高糖组(T6)鱼的肝脏中粗脂肪含量显著高于低糖组(P<0.05)。综合实验结果认为:点篮子鱼饲料糖适宜添加量为15%～25%。

Effects of dietary carbohydrate on growth performance of Siganus guttatus

A 56-day feeding trial was conducted to investigate the optimum dietary carbohydrate requirement for S.guttatus with the initial weight(34.45±10.61) g.The fishmeal and dextrin were used as protein and carbohydrate respectively.Six isonitrogenous(35% crude protein) and isoenergetic experimental diets containing 5%(T1),10%(T2),15%(T3),20%(T4),25%(T5) and 30%(T6)of carbohydrate levels were used to feed triplicate groups of 20 fish.The specific growth rate(SGR) increased with carbohydrate at a low level(less than 15%) and decreased at a higher level.And the SGR of 35% carbohydrate level was significantly lower than that of other levels(P<0.05).Feed conversion rate(FCR) had a correlation with the increasing dietary carbohydrate levels.The feed intake of 25% carbohydrate level was significantly higher than that of other levels.Dietary carbohydrate concentration also had effects on body composition and biological indices.The whole body crude protein content accumulated slightly with the increase of dietary carbohydrate concentration except group T6.Liver crude fat and muscle crude fat increased significantly with the increase of dietary carbohydrate levels.Based on second-order polynomial regression model of SGR,y=0.455 1+0.012 5x-0.000 3x2(R2=0.913 7)the optimum dietary carbohydrate requirement for juvenile S.guttatus was 20.83%.The results suggested that the optimal dietary carbohydrate level for growth of S.guttatus may be set at between 15% and 25%,when the diets contained 35% protein.