不同糖脂比对建鲤幼鱼生长、体组成、消化及糖酵解能力的影响

本试验研究了饲料中不同糖脂比对建鲤幼鱼生长、体组成、消化及糖酵解的影响。试验共配制6组等氮等能的半纯合饲料,对应糖脂比分别为2.3,3.0,4.0,5.6,7.7和12.1。将鱼饱食投喂8周,每日投喂3次。试验结果表明,当饲料糖脂比从2.3升高至7.7时,增重率、特定生长率、蛋白质效率和蛋白保留率均显著升高(P < 0.05)；而当糖脂比进一步升高时,其均呈下降趋势,但差异不显著(P > 0.05)；饲料系数的变化趋势与其相反。建鲤幼鱼的脏体比以及全鱼、胴体和肝脏脂肪含量随着饲料糖脂比的降低均显著升高(P < 0.05),而全鱼、胴体和肝脏的蛋白质含量无显著差异(P > 0.05)。肠道淀粉酶活性随着糖脂比的升高显著升高(P < 0.05),而脂肪酶的变化趋势则相反(P < 0.05)。此外,血糖和胰岛素水平、肝糖原含量及肝脏葡萄糖激酶和丙酮酸激酶活性随饲料糖脂比的升高均显著升高(P < 0.05),血液中总胆固醇和甘油三酯含量则随着糖脂比的降低显著升高(P < 0.05)。根据二次回归模型得出,在等氮等能的饲料条件下,建鲤幼鱼最适宜的糖水平和脂肪水平分别为38.21%和4.69%,对应的糖脂比为8.14。

Effects of dietary carbohydrate-to-lipid ratios on growth,body composition, digestion and glycolysis of juvenile Jian carp (Cyprinus carpio var.Jian)

The object of this study was to evaluate the effects of dietary carbohydrate-to-lipid (CHO:L) ratios on growth performance, body composition, digestive activities and glycolysis of juvenile Jian carp (Cyprinus carpio var. Jian). Fish were fed six isonitrogenous and isoenergetic diets with different (CHO:L) ratios (2.3, 3.0, 4.0, 5.6, 7.7, 12.1) three times daily for 8 weeks. The results indicated that weight gain rate (WGR), specific growth rate (SGR), protein efficiency ratio (PER) and nitrogen retention efficiency (NRE) increased significantly (P < 0.05) when dietary CHO:L increased from 2.3 to 7.7, and then they nonsignificantly decreased (P > 0.05) as dietary CHO:L ratios increased from 7.7 to 12.1, while feed conversion ratio (FCR) showed the opposite variation trend. The values of viscerosomatic index (VSI) increased significantly (P < 0.05) as dietary CHO:L ratios decreased, so as the whole body, carcass and liver lipid. There were no significant differences in whole body, carcass and liver crude protein among dietary treatments (P > 0.05). Intestine amylase activities increased significantly (P < 0.05) as dietary CHO:L ratios increased, whereas Intestine lipase activities increased significantly (P < 0.05) as dietary CHO:L ratios decreased. Liver glycogen, blood glucose and insulin increased significantly (P < 0.05) as CHO:L ratios increased. Activities of glucokinase and pyruvate kinase were stimulated significantly (P < 0.05) by elevated levels of dietary carbohydrate. However, plasma total cholesterol and triacylglyceride levels increased linearly as dietary CHO:L ratios decreased(P < 0.05). Based on a second-order polynomial regression analysis of WGR against dietary CHO:L ratios, corresponding to a CHO:L ratio of 8.14, in a diet holding 350 g/kg of crude protein and 13.2 MJ/Kg of digestive energy, proved to be optimal for juvenile Jian carp. These results demonstrated that utilization of dietary lipid and carbohydrate was moderate in juvenile Jian carp, but the fish were a little more capable of utilizing carbohydrate compared with lipid.