长吻鮠幼鱼日粮中常量营养物质适宜需求量的研究

Optimal macronutrient composition of formulated diets for juvenile longsnout catfish Leiocassis longirostris Gunther

按照Cornell法设计常量营养物质——蛋白质、脂肪和碳水化合物在日粮中的不同水平配比,以研究初始体质量为(2.0±0.1)g的长吻鮠Leiocassis longirostric Gunther幼鱼日粮中常量营养物质的适宜需求量。日粮中蛋白质、脂肪和碳水化合物水平分别设置为33%～51%、3%～18%和24%～33%(干质量,质量分数)。将1 920尾试验长吻鮠幼鱼养殖于室内水泥池中的64个网箱内,每个网箱随机放30尾鱼。试验共设计21种试验日粮,其中20种日粮(每种日粮设3个平行)分别随机投喂60个网箱中的试验鱼;1种中心组日粮设4个平行,投喂4个网箱中的试验鱼,试验共进行60 d。结果表明:除日粮蛋白质水平为33%的组长吻鮠幼鱼的成活率明显下降外(P<0.05),其余日粮中3种常量营养物质的含量对幼鱼的成活率均没有显著影响(P>0.05);当日粮蛋白质水平≤48%时,幼鱼的特定生长率随日粮蛋白质水平的上升而明显增加,当日粮蛋白质水平为33%～36%时,幼鱼的特定生长率显著降低(P<0.05);除日粮脂肪水平为6%的组外,日粮脂肪水平为9%的组幼鱼特定生长率显著高于其他日粮脂肪水平组(P<0.05),但当日粮脂肪水平≥15%后,鱼体和肝脏的脂肪含量显著上升(P<0.05);日粮中不同的碳水化合物水平对长吻鮠幼鱼的特定生长率没有显著影响(P>0.05),但当日粮碳水化合物水平为33%时,鱼体碳水化合物含量和肝脏糖原含量显著增加(P<0.05)。本研究表明,长吻鮠幼鱼日粮蛋白质、脂肪和碳水化合物3种常量营养物质的适宜需求量分别为45%、9%和≤30%,日粮总能为20.0 MJ/kg。

A three component mixture design （comell design） was used to investigate the optimal composition of macronutrients including protein from 33% to 51%, fat from 3% to 18% and carbonhydrate from 24% to 33% in dry weight for juvenile longsnout catfish Leiocassis longirostris Gunther with initial body weight of （2.0±0.1）g. A total of 1 920 test fish were randomly stocked into 64 cages displaced in an indoor tank with a tiny running water system at a rate of 30 individuals per cage. In the 60 cages, the fish were fed 20 diets with triplication, and 1 group diet with tetraplication for 60 days. The results showed that no significant effect of the dietary macronutrient composition on fish survival was observed except for the significant decline at 33% dietary protein （P〈0.05）. There was a positive effect of increasing dietary protein levels on the growth at the dietary protein level of over 48%, while dietary protein levels from 33% to 36% resulted in growth depression si^ificantlv （P〈O. 05）. Besides dietary lipid 6%, the fish fed the diet containing lipid 9% showed significantly better growth than the fish fed the diet containing other lipid levels （ P〈0.05 ）. There was significantly higher lipid contents in body or liver of the fish fed the diet containing lipid level of over 15% （P〈0.05）. There was no significant effect of dietary carbohydrate levels on the growth of the fish （P〉O. 05）, and the glycogen contents were found to be increased in whole body and liver of the fish fed the diet containing carbohydrate level of 33% （P〈O. 05）. It can be concluded that the opfimal dietary macronutrient requirement appears to be protein 45%, carbohydrate 30%, lipids 9%, and gross energy20.OMJ/kg.