Studies on the methionine requirement of carp ( Cyprinus carpio L.)

Abstract

One hundred common carp in groups of five in four tanks/treatment were each fed five diets containing different amounts of methionine. The protein in the basal diet (T-I) was supplied by soya protein, gelatin and finely ground peas ( Pisum sativum), which contained 0.49 g methionine/100 g dry matter (DM). Diets T-II to T-V were supplemented with dl-methionine to 0.61, 0.79, 1.08 and 1.34 g methionine/100 g DM. The diets also contained 0.42 g cystine/100 g DM and 40.2% crude protein in the DM. The digestibility coefficient for the crude protein was 88%, and the diets contained 16.9 MJ digestible energy (DE)/kg DM. The diets were fed at 1.8% of live weight and the experiment lasted for 85 days. Growth rate, feed intake, protein content of the fillet, viscera and residual carcass, and the plasma concentrations of met, arg, leu and trp were all increased significantly by the addition of increasing dietary methionine. The fat content of the fish and the plasma concentrations of lys, his, ser, pro and asn were increased in the fish fed diets deficient in methionine. A met requirement of 0.855 g/100 g DM or 2.13 g/100 g crude protein or 0.51 g/MJ DE was calculated using the broken-line model based on final weight and protein deposition data.