Using unessential sulfur amino acids to overcome methionine deficient diets on rice field eel (Monopterus albus)

Abstract An eight-week feeding trial was conducted using sulfur amino acids to overcome methionine deficient diets on rice field eel Monopterus albus (initial weight 25.12 ± 0.51 g). Six isonitrogenous and isoenergetic experimental formulations included 55% fish meal group (FM, a reference), 22% fish meal group (D0), and the rest four diets (22% fish meal) supplemented with 2 g/kg of taurine (DTau), methionine (DMet), cysteamine hydrochloride (DCsh) and cystine (DCys), respectively. Compared with FM, the growth performance of M. albus was markedly declined in D0 (P   0.05). Compared with FM, the highest amount of hepatic vacuoles was observed in D0, while the proportions of vacuoles were lower in DMet, DCsh and DCys groups than that in D0, dietary sulfur amino acids also have improved hepatic transaminase and the ability of amino acid metabolism. Compared with FM, muscular texture, density and diameters of muscle fibres were significantly decreased in D0 (P