Protein accretion in some fish species is affected by dietary lipids, starch and their interactions, but this aspect of nutrition is largely unknown in largemouth bass (LMB). Therefore, we designed six experimental diets with three starch levels (5%, 10%, and 15%; dry matter basis) and two lipid levels (10% and 12.5%; dry matter basis) to evaluate the effects of dietary starch and lipid levels on the protein retention, growth, feed utilization, and liver histology of LMB. There were three tanks (18 fish per tank, ~ 4.85 g per fish) per dietary treatment group and the trial lasted for 8 weeks. Fish were fed to apparent satiation twice daily. Results indicated that increasing the dietary starch level from 5 to 15% reduced (P < 0.05) absolute feed intake (AFI; − 9.0%, − 15% and − 14% on days 14–28, 28–42, and 42–56, respectively) and weight gains (− 4.4% and − 6.5% on days 42 and 56, respectively) of LMB. Increasing the dietary lipid level from 10 to 12.5% reduced (P < 0.05) AFI (− 9.7%, − 11.7% and − 11.9% on days 14–28, 28–42; and 42–56, respectively), weight gains (− 4.2%, − 5.9% and − 6.9% on days 28, 42 and 56, respectively), and survival rate (by a 5.6% unit) of LMB. The retention of dietary protein and some amino acids in the body was affected by dietary starch or lipid levels and their interactions. The viscerosomatic index (VSI), hepatosomatic index (HSI), and intraperitoneal fat ratio (IPFR) increased with increasing the dietary starch level from 5 to 15%. Compared with 10% lipids, 12.5% lipids in diets increased IPFR but had no effect on VSI or HSI. The concentrations of glucose in serum increased with increasing the dietary starch level from 5 to 15% at 4 to 24 h after feeding, with the effect of dietary lipids being time-dependent. Compared with a 5%-starch diet, fish fed a diet with 10%- or 15%-starch exhibited an enlarged and pale liver with excessive glycogen. Based on these findings, we recommend dietary lipid and starch levels to be 10% and < 10%, respectively, for juvenile LMB to maximize the retention of dietary protein in their bodies.

中文翻译：

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膳食淀粉和脂质水平对大嘴鲈（Micropterus salmoides）的蛋白质保留和生长的影响。

某些鱼类的蛋白质增生受到饮食中脂质，淀粉及其相互作用的影响，但是大口黑鲈（LMB）的营养这一方面在很大程度上是未知的。因此，我们设计了六种实验饮食，分别以三种淀粉水平（5％，10％和15％；以干物质为基础）和两种脂质水平（10％和12.5％；以干物质为基础）来评估膳食淀粉和脂质的影响LMB的蛋白质保留，生长，饲料利用率和肝脏组织学水平。每个饮食治疗组有3个储水箱（每储水箱18条鱼，每条鱼约4.85克），试验持续了8周。每天两次对鱼进行明显的饱食。结果表明，将膳食淀粉水平从5％提高到15％（P <0.05）绝对采食量（AFI;在14-28、28-42和42-56天分别为9.0％，-15％和-14％）和体重增加（在几天内为-4.4％和-6.5％ LMB（分别为42和56）。饮食脂质水平从10增加到12.5％减少了（P <0.05）AFI（分别在第14-28、28-42和42-56天分别为-9.7％，-11.7％和-11.9％），体重增加（分别为-4.2％，-5.9％和-6.9％ LMB的生存率（分别为28、42和56）和生存率（按5.6％的单位）。膳食淀粉和脂质水平及其相互作用会影响人体中膳食蛋白质和某些氨基酸的保留。随着饮食淀粉水平从5％增加到15％，内脏指数（VSI），肝素指数（HSI）和腹膜内脂肪比率（IPFR）增加。与10％的脂质相比，日粮中的12.5％的脂质可增加IPFR，但对VSI或HSI没有影响。饲喂后4至24小时，血清中葡萄糖的浓度随着膳食淀粉水平的增加从5％增加到15％而增加，膳食脂质的作用是时间依赖性的。与5％淀粉饮食相比，饲喂淀粉含量为10％或15％的鱼，肝脏肿大，苍白，糖原过多。基于这些发现，我们建议幼年LMB的饮食脂质和淀粉水平分别为10％和<10％，以最大程度地保留其体内的饮食蛋白。