Natural liquid betaine dietary supplementation improves growth performance, immuno-antioxidant responses, and stress resistance in Nile tilapia subjected to acute ammonia challenge

Abstract This work investigated the effects of natural liquid betaine (NATURA BETAINE) dietary supplementation on physiological performance and alleviation of acute ammonia toxicity in Nile tilapia. Four diets supplemented with 0.0, 0.8, 1.6, and 2.4 mL of liquid betaine /kg diet, representing the experimental treatments B0, B800, B1600, and B2400, respectively, in triplicates were used. Each replicate included 15 Nile tilapia fingerlings (N = 180, initial weight: 9.5 ± 0.429 g). Fish were fed at the rate of 4% of their body weight twice daily for 60 days. At the termination of this feeding trial, the groups B0 randomly divided into two parts B0 − ve and B0 + ve [control negative, and positive, respectively based on ammonia exposure. Then the groups B0 + ve, B800, B1600, and B2400 were subjected to acute ammonia challenge for 72 h, using ammonium chloride at 0.07 g/L. After the 60 days feeding trial, fish received liquid betaine supplemented diets displayed greater growth performance and feed utilization compared to the control group (B0). Additionally, betaine supplementation enhanced serum amylase and lipase concentrations and hematobiochemical metrics. The high dose of liquid betaine (B2400) increased antioxidant enzyme activities and lowered malondialdehyde concentration with increasing serum lysozyme activity and IgM concentrations, and phagocytic activity, and index. At molecular level, betaine dietary supplementation induced upregulations in the mRNA copies of some growth-, immuno- and antioxidant-related genes. Following ammonia exposure, betaine supplementation, particularly the highest dose (B2400) enhanced the cumulative survival rate and mitigated the inflammation signs and tissue degeneration caused by the ammonia challenge in liver, intestine, and gill tissues. In conclusion, dietary supplementation of NATURA BETAINE (at 2.4 mL kg −1 ) enhanced growth performance, optimized physio-biochemical homeostasis, reinforced innate immune and antioxidant responses which may enhance resilience to ammonia stress by improving survival and reducing tissue damage in Nile tilapia, supporting its application as an effective feed additive in aquaculture.