新型蛋白源替代饲料中鱼粉对星斑川鲽(Platichthys stellatus)幼鱼氨基酸组成的影响

THE EFFECTS OF NEW PROTEIN SOURCES SUBSTITUTE FISHMEAL ON THE AMINO ACID COMPOSITIONS OF JUVENILE STARRY FLOUNDER PLATICHTHYS STELLATUS

以新型蛋白源(大豆浓缩蛋白、脱酚棉籽蛋白、喷雾血球蛋白粉)分别替代基础饲料(D0)中17%(D17)、35%(D35)、52%(D52)和69%(D69)的鱼粉,配制5种等氮等能的饲料,饲喂星斑川鲽幼鱼[初始体重(75.6±0.18)g]60d,以考察鱼粉替代对星斑川鲽幼鱼氨基酸组成的影响。结果表明,试验组肌肉Arg和His含量显著增大(P<0.05),Thr含量差异不显著(P>0.05),其它必需氨基酸(EAA)含量均显著降低(P<0.05);试验组全鱼EAA总量无显著性差异(P>0.05)。D69组肝脏天冬氨酸氨基转移酶(AST)和天冬氨酸氨基转移酶/丙氨酸氨基转移酶(AST/ALT)显著低于其它各组(P<0.05);血清AST及AST/ALT随鱼粉替代量的增加显著增大(P<0.05)。本试验条件下,当替代饲料中35%的鱼粉时,饲料EAA消化率及试验鱼肌肉和全鱼氨基酸组成均无显著性差异,替代比例进一步加大,会对试验鱼肝脏生理功能产生影响。

Starry flounder Platichthys stellatus is a type of large carnivorous fish and their diet requires high level of protein. Using juvenile fish with initial body weight of （75.6±0.18）g, we tested the effects of different fishmeal substitutes on the starry flounder. Five isonitrogenous and isoenergetic diets were formulated by adjusting amino acid level using three different protein sources （soy protein concentrate, dephenolized cottonseed protein, spray-dried blood protein）, crystalline Lysine and Methionine. D0 with 58% defatted fishmeal as the control group, and added the fishmeal substitutes at four levels of 17% （D17）, 35% （D35）, 52% （D52）, 69% （D69） to the fish diet. Five groups in triplicate were divided randomly for the following 60-day feeding experiment. We found that the D17 and D35 groups were not significantly different from the control group in the digestibility of essential amino acids （EAA） （P0.05）, although their EAA contents were significantly higher than those in the D52 and D69 groups （P0.05）. Compared with the control group, except arginine, histidine and threonine, the contents of other EAA in the fish muscles decreased significantly （P0.05）, although the total contents of the EAA did not exhibit significant difference in whole fish （P0.05）. Furthermore, the contents of valine and methionine declined markedly （P0.05）. In the D69 treatment group, liver AST and AST/ALT ratio were significantly lower than other groups （P0.05）, whereas serum AST and AST/ALT ratio increased dramatically with increasing substituting protein. Our results showed that there was no significant difference on apparent digestibility of EAA in diets, muscle and whole fish EAA contents when up to 35% of the fishmeal was substituted by the alternative protein sources, but the liver function of the experimental fish was affected at higher alternative protein levels.