AUTHOR=Zhang Shuze , Wang Chang’an , Liu Siyuan , Wang Yaling , Lu Shaoxia , Han Shicheng , Jiang Haibo , Liu Hongbai , Yang Yuhong 

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

JOURNAL=Frontiers in Nutrition

VOLUME=Volume 10 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2023.1008822

DOI=10.3389/fnut.2023.1008822

ISSN=2296-861X

ABSTRACT=This study aimed to investigate the effects of phenylalanine on the growth, digestive and absorptive capacity, antioxidant capacity, 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%, 3.01%) were fed to triplicate groups of 20 fish (initial mean body weight of 38.65 ± 0.62 g). Weight gain rate (WGR) and specific growth rate (SGR) 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). Serum superoxide dismutase (SOD) activity and liver peroxidase (CAT) activity both reached their maximum in the 2.03% group. Interleukin factors IL-1β and IL-6 both reached a minimum value in the 2.03% group and were significantly lower than the control group, while IL-10 reached a maximum value in the 2.03% group (P<0.05). The tight junction protein-related genes occludin, claudin-1, and ZO-1 all reached a maximum in the 2.03% treatment group and were significantly higher than the control group (P<0.05). There were also significant differences in intestinal villi length and muscle layer thickness among the groups (P<0.05). In conclusion, dietary phenylalanine effectively improved the growth, digestion and absorption capacity, antioxidant capacity, and intestinal health of O. mykiss. Using a quadratic curve model analysis based on WGR, dietary phenylalanine requirement of triploid O. mykiss fed a low fish meal diet (15%) was 2.13%.