Arginine requirement and effect of arginine intake on immunity in largemouth bass, Micropterus salmoides

摘要

An 8-week feeding test was conducted to quantify the dietary arginine requirement of juvenile largemouth bass (LMB) (25?±?0.4?g). Six isonitrogenous and isolipidic (459?g crude protein and 122?g crude lipid kg?1 dry diet) diets were formulated to contain graded levels of arginine (17.0–30.1?g?kg?1 dry diet). Zein-coated crystalline amino acid mixtures were supplemented to simulate, except for arginine, the amino acid profile of the muscle protein of LMB. Each diet was randomly assigned to quadruplicate tanks of 35 fish reared in a flow-through system. Fish were fed to apparent satiation twice daily. Weight gain (WG) was significantly affected by dietary arginine level. Nitrogen retention was significantly lower in fish fed D17.0. Arginine retention significantly decreased with dietary arginine increased. Threonine, leucine and lysine concentrations in whole body were significantly affected by dietary arginine level. Serum lysozyme activity, serum protein and respiratory burst of head kidney leucocytes were significantly affected, while complement activity (CH₅₀) showed no difference among treatments. Based on broken-line analysis for WG against dietary digestible arginine level, the arginine requirement of LMB was 19.1?g?kg?1 of dry diet (41.6?g?kg?1 of crude protein).