Functional Properties of Protein Hydrolysates on Growth, Digestive Enzyme Activities, Protein Metabolism, and Intestinal Health of Larval Largemouth Bass (Micropterus salmoides)

Abstract

The present study was conducted to investigate the effects of dietary inclusion of protein hydrolysates on growth performance, digestive enzyme activities, protein metabolism, and intestinal health in larval largemouth bass (Micropterus salmoides). The experimental feeding trial presented in this study was based on five isonitrogenous and isolipidic diets formulated with graded inclusion levels of protein hydrolysates, and it showed that protein hydrolysates improved growth performance, reduced larval deformity rate, and increased the activity of digestive enzymes, including pepsin and trypsin. Gene expression results revealed that the supplementation of protein hydrolysates upregulated the expression of intestinal amino acid transporters LAT2 and peptide transporter 2 (PepT2), as well as the amino acid transporters LAT1 in muscle. Dietary provision of protein hydrolysates activated the target of rapamycin (TOR) pathway including the up-regulation of TOR and AKT1, and down-regulation of 4EBP1. Additionally, the expression of genes involved in the amino acids response (AAR) pathway, ATF4 and REDD1, were inhibited. Protein hydrolysates inhibited the transcription of some pro-inflammatory cytokines, including IL-8 and 5-LOX, but promoted the expression of anti-inflammatory cytokines TGF-β and IL-10. The 16S rRNA analysis, using V3-V4 region, indicated that dietary protein hydrolysates supplementation reduced the diversity of the intestine microbial community, increased the enrichment of Plesiomonas and reduced the enrichment of Staphylococcus at the genus level. In summary, protein hydrolysates have been shown to be an active and useful supplement to positively complement other protein sources in the diets for largemouth bass larvae, and this study provided novel insights on the beneficial roles and possible mechanisms of action of dietary protein hydrolysates in improving the overall performance of fish larvae.

Fish waste to sustainable additives: Fish protein hydrolysates alleviate intestinal dysbiosis and muscle atrophy induced by poultry by-product meal in Lates calcarifer juvenile

“…This was supported by a higher expression of both tnf-α and il-10 in PBM-FPH fed groups when compared to those fed PBM-based diet, and the results were comparable to fish fed the FM control diet. Dietary supplementation of FPHs provided a similar beneficial effect on inflammatory responses in the intestine of larval largemouth bass, manifested by the downregulation of pro-inflammatory cytokines ( 5-lox and il-8 ) and upregulation of anti-inflammatory cytokines ( il-10 ) ( 22 ). These authors reported that the presence of high amounts of free histidine and glycine in FPHs supressed the inflammatory response in largemouth bass.…”

“…These authors reported that the presence of high amounts of free histidine and glycine in FPHs supressed the inflammatory response in largemouth bass. Also, the inhibitory effects of anti-inflammatory cytokines on the expression of pro-inflammatory cytokines have been reported to be suppressed in the inflammatory response in some teleost fish ( 22 ).…”

“…Similarly, 10% of FPH supplemented with 80% of plant protein in the diet of Atlantic salmon, Salmo salar , resulted in a significant increase in growth performance and health ( 7 ). Supplementation of FPH also benefited the overall immunity of largemouth seabass, Micropterus salmoides, increased anti-inflammatory cytokines ( tgf-β and il-10 ), and reduced pro-inflammatory cytokines ( il-8 ), ( 22 ). In alternative protein studies, it is important to understand the interaction between intestinal mucosal barrier functions, microbiota, and anti-inflammatory cytokines in maintaining intestinal homeostasis.…”

Effects of Lysophospholipid Supplementation in Feed with Low Protein or Lipid on Growth Performance, Lipid Metabolism, and Intestinal Flora of Largemouth Bass (Micropterus salmoides)

“…Higher dietary lipid and protein contents in aquafeeds not only increase farming cost but also lead to waste and ammonia emissions. However, lower dietary lipid or protein contents could result in negative effects on fish growth performance [ 2 , 3 ]. Therefore, how to save cost and at the same time to maintain development quality has become an important and urgent issue.…”

“…Vitamin premix and mineral premix (Yuehai Brand®) by Guangdong Yuehai Feed Group Co. Ltd., Zhanjiang, China 2. Provided by Kemin AquaScience (Zhuhai, China) 3. Exchange rates are applied: $1 = ￥6:7089.…”