An evaluation on betaine and trimethylammonium hydrochloride in the diet of Carassius auratus: Growth, immunity, and fat metabolism gene expression

Abstract

A 6-week feeding trial was conducted to evaluate the effects of betaine power (B-30) and trimethylammonium hydrochloride (T-98) in practical diet on growth performance, immunity, and fat metabolism gene expression of Carassius auratus (initial body weight: 3.37 ± 0.03 g). Control group was fed the basal diet, while four other groups were fed the basal diet supplemented with 1.4 g/kg B-30 (L-B group), 2.8 g/kg B-30 (H-B group), 0.5 g/kg T-98 (L-T group), and 1.0 g/kg T-98 (H-T group). The results revealed a significant improvement in specific growth rates, feed conversion ratio, and weight gain rate with L-B and L-T groups compared to control group, as well as digestive enzyme activity (lipase, amylase and protease) and immunoenzyme activity (acid phosphatase, alkaline phosphatase, lysozyme, catalase from micrococcus lysodeikticu, total antioxidant capacity, and superoxide dismutase) (P < 0.05). Futhermore, the gene expression levels of lipoprotein lipase and liver lipase in L-B and L-T groups were significantly increased compared with the control group, while the gene expression levels of fatty acid synthase were significantly decreased (P < 0.05). These data suggested that supplementation of 1.4 g/kg betaine or 0.5 g/kg trimethylammonium hydrochloride can improve the growth performence, digestive capacity, immunity, and fat metabolism gene expression of C. auratus.