为研究饲料糖水平对吉富罗非鱼幼鱼生长性能和肝代谢功能的影响,实验配制等蛋白、等脂肪含量的8种不同糖水平(10%、15%、20%、25%、30%、35%、40%和45%)饲料,每个糖水平设3个重复,饲养周期49 d,结果显示:(1)饲料糖水平对吉富罗非鱼幼鱼的增重率、成活率、饲料系数和肝体比均有显著影响(P<0.05)。饲料糖水平为35%时,罗非鱼增重最快;饲料糖水平为40%时饲料系数最低。(2)随着饲料糖水平的升高,鱼体肌糖原、粗脂肪含量逐渐升高,鱼体肝糖原含量先增加后下降。(3)饲料糖水平对各组鱼血清谷草转氨酶、谷丙转氨酶、血清磷酸果糖激酶活性、总蛋白和总胆汁酸浓度均有显著影响(P<0.05),且随着糖水平的升高,呈上升趋势;而鱼体肝酯酶和脂蛋白脂酶活性则是先上升后下降。(4)饲料糖水平35%时,肝脏组织出现少量细胞脂滴空泡状现象;饲料糖水平40%和45%时,肝脏组织切片有明显的细胞脂滴空泡状、核偏移和细胞质消失现象。肝脏脂滴空泡状面积率与组织脂肪含量具有显著的正相关,与肝脏组织的脂肪肝病变程度成正比。结果表明,吉富罗非鱼苗种饲料以29.10%～35.00%的糖水平较利于吉富罗非鱼幼鱼生长及后期的脂肪肝病预防。

This study was to investigate the effect of dietary carbohydrate levels on juvenile tilapia(Oreochromis niloticus)growth performance and liver metabolism functions.Eight groups of 1 200 tilapias,in triplicate,with initial body weight of(0.36±0.01)g were fed eight experimental diets(similar protein and lipid contents but carbohydrate levels were 10%,15%,20%,25%,30%,35%,40%,45%,respectively).After 7 weeks feeding,the results showed that:(1)dietary carbohydrate level had significant effects on weight gain rate,survival rate,feed conversion ratio and hepato-somatic index(HSI)in tilapia juvenile(P<0.05).The growth rate of the fish fed the diet of 35% carbohydrate level was the highest among the treatments,and the feed conversion ratio of the fish fed the diet of 40% carbohydrate level was the lowest.(2)With increasing of dietary carbohydrate,the muscle glycogen and crude fat content gradually increased.However,the glycogen content rose initially and then declined.(3)The activities of serum alanine aminotransferase,aspartate aminotransferase,phosphofructokinase,and the concentrations of serum total protein and total bile acid were all significantly increased with the elevated levels of carbohydrate(P<0.05).However,the activities of liver esterase and lipoprotein lipase rose initially and then declined.(4)Liver tissues displayed a few lipid vacuolations in hepatocyte cells at 35%.At the carbohydrate level over 40%,liver histological sections showed a large number of hepatocyte lipid droplets vacuolar degeneration,nuclear migrations and cytoplasm disappearances.The lipid vacuolation areas in liver histological sections basically tallied with the lipid content of the liver,which were consistent with the severity of fatty liver.In conclusion,according to the observation of growth and prevention of late fatty liver disease,the most appropriate proportion of carbohydrate in the fish diet is around 29.10%-35.00%.

国家自然科学基金项目(31260640);国家“十二五”科技支撑计划(2012BAD25B04);广西 “十二五”重大科技专项(1123010);广西科技攻关项目(0992014-2)