Effects of Supplemental Lysine and Methionine on Growth Performance and Body Composition for Grass Carp (Ctenopharyngodon idella)

Problem statement: The utilization of crystalline amino acids was detected for growth performance and body composition of juvenile grass carp (Ctenopharyngodon idella). Approach: L-Lysine sulphate and Methionine Hydroxy Analog-Ca (MHA-Ca) were selected for determination. Two diets were formulated with or without amino acids supplementation. Each diet was assigned to 10 tanks in a completely randomized design for 8 weeks. Results: The results demonstrated that the final weight, Weight Gain (WG) and Protein Retention (PR) of the fish fed diet with supplemental lysine and methionine were significantly higher, while the Feed Conversion Ratio (FCR) were significantly lower in comparison with the reference group. The Condition Factor (CF) of the fish fed diet with lysine and methionine supplementation were significantly higher than the reference group (p<0.05). However, the Viscera Somatic Index (VSI), Hepato Somatic Index (HSI) and Intra Peritoneal Fat Ratio (IPFR) of the tested group were markedly lower (p<0.05). Whole body moisture and muscle protein content of the tested fish significantly increased, while the lipid level of whole body significantly decreased (p<0.05) with the supplementation of lysine and methionine. Conclusion: Results of the present investigation demonstrate significant improvement of growth and feed utilization of grass carp can be achieved by L-Lysine sulphate and MHA-Ca supplementation. WG and PR of the tested group improved 11.4% and 8.3% respectively, while FCR decreased 9.6% in comparison with the reference group (p<0.05).