Effect of Dietary Alanine and Glycine Supplementation on Growth Performance, Body Composition and Apparent Nutrient Digestibility of Juvenile Grass Carp (Ctenopharyngodon idella)

Abstract

A 42-day growth trial was undertaken to estimate the effects of supplemented alanine and glycine on growth performance, feed utilization, and apparent digestibility of nutrients in juvenile grass carp (Ctenopharyngodon idella). Three diets were compared: 1) fishmeal (FM), 2) soybean meal (SBM) and 3) alanine and glycine supplemented (NEAA) where alanine and glycine were added to the soybean diet to achieve the desired alanine and glycine content in FM diet. Results showed that NEAA diet decreased the feed conversion ratio (FCR) by 15.3%, improved average final weight by 13.4%, and increased 14.0% of protein retention compared with the SBM diet (P<0.05). In grass carp fed the SBM diet muscle protein and lipid content were significantly higher than those fed the FM and NEAA diets (P<0.05). Serum AST, ALT, ALP activities of fish fed the FM diet were significantly lower than the SBM diet (P<0.05), and similar to the NEAA diet (P>0.05). Serum urea content from the NEAA diet was significantly lower than FM and SBM diets (P<0.05). In conclusion, while adding alanine and glycine to a plant based diet can improve the growth performance, liver function, and protein utilization of juvenile grass carp, it does not improve performance to the levels of an FM diet.