在低蛋白质饲料中补充必需氨基酸对大口黑鲈生长、体组成和免疫指标的影响

EFFECTS OF SUPPLEMENTING EAA TO LOWER PROTEIN DIETS ON GROWTH, BODY COMPOSITION AND IMMUNOLOGICAL INDEX OF LARGEMOUTH BASS(MICROPTERUS SALMOIDES)

为了研究在低蛋白质饲料中补充晶体必需氨基酸对大口黑鲈生长、体组成和免疫指标的影响,根据鱼体的必需氨基酸组成模式设计了7种等能的试验饲料。其中4种饲料(45CP、40CP、35CP和30CP)的粗蛋白质水平分别为45%、40%、35%和30%,另3种饲料(40AA、35AA和30AA)是在低蛋白质饲料(40CP、35CP和30CP)的基础上添加必需氨基酸,使它们的必需氨基酸含量与45CP(对照组)相一致。用上述饲料对初始体重为(10.13±0.01)g的大口黑鲈进行了89d的饲养试验。饲养试验在室内循环水养殖系统中进行,每种饲料设3个重复,每重复放养30尾鱼。方差分析显示:试验鱼的生长性能、饲料效率、全鱼和肌肉的粗蛋白质含量、成活率以及免疫指标均随着饲料蛋白质含量的降低而显著降低(P<0.05)。添加必需氨基酸的35AA和30AA的饲料效率和蛋白质保留率分别显著高于对应的未添加必需氨基酸的35CP和30CP组(P<0.05),但仍显著低于45CP组(P<0.05)。40AA的试验鱼血清溶菌酶活性和血清补体活性与45CP组差异不显著(P>0.05)。35AA和30AA组的头肾白细胞呼吸爆发活性显著高于35CP和30CP组(P<0.05)。30AA组的全鱼粗蛋白质含量以及肥满度显著高于30CP(P<0.05)。各组试验鱼的水分和灰分均无显著差异(P>0.05)。回归分析显示:在低蛋白质饲料中补充晶体必需氨基酸对大口黑鲈幼鱼的生长、饲料效率和蛋白质保留率所产生的影响与其引起增加了的饲料蛋白质水平而不是饲料的必需氨基酸水平正相关。研究表明,在低蛋白质饲料中补充的晶体必需氨基酸对大口黑鲈的生长、体组成和免疫指标产生的有益作用不及等量的以蛋白质为来源的必需氨基酸。

An 89-day growth trial was undertaken to evaluate effects of essential amino acid （EAA） supplementation to diets with lower protein levels on growth performance, body composition and immunological parameters in largemouth bass （Micropterus salmoides）. Seven isoenergetic diets were formulated according to the EAA profile of whole body of largemouth bass. Four diets of them contained crude protein concentrations of 45%, 40%, 35% and 30%, respectively （designated as 45CP, 40CP, 35CP and 30CP）. The other three diets （designated as 40AA, 35AA and 30AA） were formu-lated by adding EAA to three lower protein diets of 40CP, 35CP and 30CP to make their EAA levels consistent with that of 45CP （used as a control）. Triplicate groups of thirty juvenile largemouth bass with initial body weight of （10.13±0.01） g were reared in an indoor water-circulating system. It was showed by one-way ANOVA that growth performance, feed utilization, crude protein concentrations of whole body and muscle, immunological index and survival rate declined significantly among fish fed the diets with a reduction of dietary protein from 45%to 30%（P〈0.05）. Feed efficiency and protein retention in fish fed 35AA and 30AA were significantly higher than those of 35CP-and 30CP-fed fish （P〈0.05）, respectively. There were no significances in serum lysozyme activity and serum complement activity between 40AA-fed fish and 45CP-fed fish （P〉0.05）. Respiratory burst activity of head kidney leukocytes with 35AA-fed fish and 30AA-fed fish was significantly higher （P〈0.05）, compared to those of 35CP and 30CP, respectively. Crude protein concentrations of whole-body and condition factor of 30AA-fed fish were significantly higher than those 30CP-fed fish （P〈0.05）. Among all the treatments, moisture and ash of whole body and muscle of tested fish showed no significant differences （P＆gt;0.05）. It was suggested by regression analysis that the effects of supplementing EAA to lower protein diets on SGR, FE and PR in juvenile largemouth bass were positively related with increased levels of dietary protein rather than those of dietary EAA. This study indicates that crystalline EAA supplemented to lower protein diets for juvenile largemouth bass can cause improvement in growth performance, feed efficiency and immunological index but the improvement is inferior to what is caused by the same levels of EAA deriving from proteins.