Effect of dietary phenylalanine on growth performance and intestinal health of triploid rainbow trout (Oncorhynchus mykiss) in low fishmeal diets

Abstract

This study aimed to investigate the effects of phenylalanine on the growth, digestive capacity, antioxidant capability, and intestinal health of triploid rainbow trout (Oncorhynchus mykiss) fed a low fish meal diet (15%). Five isonitrogenous and isoenergetic diets with different dietary phenylalanine levels (1.82, 2.03, 2.29, 2.64, and 3.01%) were fed to triplicate groups of 20 fish (initial mean body weight of 36.76 ± 3.13 g). The weight gain rate and specific growth rate were significantly lower (p < 0.05) in the 3.01% group. The trypsin activity in the 2.03% group was significantly higher than that in the control group (p < 0.05). Amylase activity peaked in the 2.64% treatment group. Serum superoxide dismutase, catalase, and lysozyme had the highest values in the 2.03% treatment group. Liver superoxide dismutase and catalase reached their maximum values in the 2.03% treatment group, and lysozyme had the highest value in the 2.29% treatment group. Malondialdehyde levels in both the liver and serum were at their lowest in the 2.29% treatment group. Interleukin factors IL-1β and IL-6 both reached a minimum in the 2.03% group and were significantly lower than in the control group, while IL-10 reached a maximum in the 2.03% group (p < 0.05). The tight junction protein-related genes occludin, claudin-1, and ZO-1 all attained their highest levels in the 2.03% treatment group and were significantly higher compared to the control group (p < 0.05). The intestinal villi length and muscle layer thickness were also improved in the 2.03% group (p < 0.05). In conclusion, dietary phenylalanine effectively improved the growth, digestion, absorption capacity, antioxidant capacity, and intestinal health of O. mykiss. Using a quadratic curve model analysis based on WGR, the dietary phenylalanine requirement of triploid O. mykiss fed a low fish meal diet (15%) was 2.13%.

Exploring the dietary strategies of phenylalanine: Improving muscle nutraceutical quality as well as muscle glycogen and protein deposition in adult grass carp (Ctenopharyngodon idella)

“…The results showed that dietary Phe enhanced the content of muscle fat and protein in grass carp. Similar results were found in triploid rainbow trout ( Zhang et al, 2023 ). Free amino acids (FAA) are considered taste-active compounds, participating in the Maillard reaction and imposing profound influences on the final flavor ( Reina et al, 2014 ).…”

“…Phenylalanine (Phe), as one of the EAAs in animals, is not only a precursor substance for protein synthesis but also participates in glycolipid metabolism in the organism as one of the ketogenic amino acids ( Guo et al, 2022 ). Previous studies have shown that an appropriate level of Phe could promote the growth of young grass carp ( Li et al, 2015 ) and triploid rainbow trout ( Oncorhynchus mykiss ) ( Zhang et al, 2023 ). Fish growth mainly involves the development of muscles ( Xiao et al, 2023 ).…”

“…Tyr phosphorylation can activate AKT signaling in cells ( Chen et al, 2001 ). A study demonstrated that Phe can lower cysteamine (Cys) levels in triploid rainbow trout ( Oncorhynchus mykiss ) ( Zhang et al, 2023 ). Cys could reduce the mRNA level of FOXO4 in the skeletal muscle of finishing pigs ( Blachier et al, 2015 ).…”

Multi-omics analysis of miRNA-mediated intestinal microflora changes in crucian carp Carassius auratus infected with Rahnella aquatilis

“…R. aquatilis is an emerging pathogen affecting both fish and humans, causing enteritis, septicemia, and death in severe cases ( 30 , 31 , 36 , 45 , 46 ), and has resulted in significant economic losses to fish farmers in China. Recent studies indicated that the thickness of the mucosal layer, muscular layer, and intestinal villus length was decreased after bacterial infection ( 47 , 48 ), and the pathological changes were basically consistent with those of the presently studied crucian carp infected with R. aquatilis . The enzyme activities of ALT, AST, and AKP were usually used in the disease-resistance immune and pathological damage ( 49 ).…”

Enhancing Growth and Intestinal Health in Triploid Rainbow Trout Fed a Low-Fish-Meal Diet through Supplementation with Clostridium butyricum

“…By optimizing feed formulations and supplementing effective additives, it is feasible to sustain optimal nutrition and growth in rainbow trout, even with reduced fish meal content. Previous nutritional assessments in our laboratory have shown that triploid rainbow trout can maintain normal growth and development with a fish meal inclusion level of 15% [15,16]. However, research into the effects of C. butyricum supplementation in low-fish-meal diets, particularly its impact on the immune response, intestinal inflammation-related gene expression, and microflora in triploid rainbow trout, remains scarce.…”