Effects of dietary arginine levels on growth performance, body composition, serum biochemical indices and resistance ability against ammonia-nitrogen stress in juvenile yellow catfish ( Pelteobagrus fulvidraco )

This experiment was conducted to investigate the effects of dietary arginine levels on growth performance, body composition, serum biochemical indices and resistance ability against ammonia-nitrogen stress in juvenile yellow catfish (Pelteobagrus fulvidraco). Five isonitrogenous and isolipidic diets (42% protein and 9% lipid) were formulated to contain graded levels of arginine (2.44%, 2.64%, 2.81%, 3.01% and 3.23% of diet), by supplementing L-Arginine HCl. Seven hundred juvenile yellow catfish with an initial average body weight of 1.13 ± 0.02 g were randomly divided into 5 groups with 4 replicates of 35 fish each and each group was fed one of the diets. After 56 d feeding, fish were exposed to 100 mg/L of ammonia-nitrogen for 72 h. The results showed that weight gain (WG) and specific growth rate (SGR) in 2.64% and 2.81% groups were significantly higher than those in 3.23% group (P P P P > 0.05). After the fish were challenged to ammonia-nitrogen for 72 h, their cumulative mortality rate in 2.81% group was significantly lower than that in 2.44% group (P < 0.05). The results suggested that dietary arginine level at 2.81% could optimize anti-ammonia-nitrogen stress ability of juvenile yellow catfish and a level of 3.23% arginine seemed to depress the growth performance of fish and decreased their tolerance to the ammonia-nitrogen stress under current study. A quadratic regression analysis based on WG indicated that the optimal dietary arginine requirement of juvenile yellow catfish was estimated to be 2.74% of the diet (6.45% of dietary protein) under current culture conditions.