Effects of intermittent fasting on growth, metabolism and stress resistance in freshwater crayfish ( Procambarus clarkii )

Intermittent fasting (IF) is a dietary pattern that involves consuming less food during specific periods or not consuming food at all during certain regular feeding periods. The feeding regimen of crayfish affects their growth quality and physiological conditions. In this study, a control group (C group) was fed every day, and three periodic IF groups F1, F2, and F4 were set up, with treatment of 1 day of feeding and 1 day of fasting (1:1), 2 days of feeding and 1 day of fasting (2:1), and 4 days of feeding and 1 day of fasting (4:1), respectively. Growth performance, stress resistant ability and metabolic changes were then evaluated to explore the effects of IF on crayfish. There was no death during the experiment. F2 group exhibited the highest molting rate and weight gain, which were significantly different from those of the other groups. Additionally, F2 group had the lowest feed coefficient, with a significant difference compared to C group ( P <0.05). Feed intake of feeding days of F2 group was significantly higher than that of C group ( P <0.01) and there was no significant difference between F1, F4 groups and C group ( P >0.05). 2:1 IF had a great impact on the growth and food intake of crayfish. Results of enzyme activities showed that IF had a certain effect on crayfish protein and starch digestion, but the impact on the improvement of immune and antioxidant capacity was not obvious. Metabolomics analysis of hepatopancreas showed that IF mainly regulated pyrimidines, nucleotides, nucleotide sugar metabolism, biotin and cofactor metabolism, starch and sucrose metabolism, and also made some changes in amino acids with neurotransmitter functions and in sex hormones. The findings suggest that IF promotes the molting and growth of crayfish, and may potentially stimulate cell proliferation, improve exercise ability, and affect gonadal development and reproductive status. This study provides insight into effects of IF on crayfish.