Effects of dietary choline chloride on growth performance, antioxidant properties, and intestinal function of juvenile bighead carp (Aristichthys nobilis)

To investigate the effects of choline chloride on growth performance, antioxidant properties, and intestinal function of juvenile bighead carp (Aristichthys nobilis), fish with an average weight of 1.77g were fed with different dietary choline chloride supplementation concentrations: 0 g/kg (control), 2 g/kg, 4 g/kg, 6 g/kg, 8 g/kg and 10 g/kg for 66 days. The results indicated that dietary choline chloride supplementation at 6 g/kg improved the weight gain rate (WGR) and specific growth rate (SGR) (P<0.05). Dietary choline chloride supplementation (approximately 4-10 g/kg) decreased serum in serum triglycerides, total cholesterol and glucose levels of juvenile bighead carp (P<0.05). Malondialdehyde level was significantly lower than the control group when choline chloride supplementation ranged from 6 to 10g/kg. When choline chloride supplementation was at 6 g/kg, the activities catalase and superoxide dismutase were significantly higher than the control group (P<0.05). The levels of choline chloride supplementation (approximately 6-10 g/kg) increased the activity of intestinal digestive enzymes and enhanced the intestinal digestibility of juvenile bighead carp (P<0.05). In addition, choline chloride levels did not affect the abundance of intestinal microbiota. And the composition of the dominant phylum genera was similar, at the phylum level, there were Ascomycetes, Actinobacteria, and Thick-walled Bacteria. At the genus level, there are Gemmobacter, ZOR0006 , Peredibacter and Mycobacterium, respectively. Overall, choline chloride supplementation (4-10 g/kg) could significantly improve the growth performance, antioxidant capacity, and digestive enzyme activity of juvenile bighead carp. Furthermore, broken-line regression analysis has identified 6.51 and 6.62 g/kg as the optimal levels of dietary choline chloride for juvenile bighead carp based on growth performance.