Amino acid composition of carp ( Cyprinus carpio L.) with varying protein and energy supplies

Abstract

In two trials (A and B) carp ( Cyprinus carpio L.) received six different feed mixtures made by combining three different crude protein levels (trial A, 20%, 30% and 41% crude protein (CP); trial B, 41%, 46% and 51% CP), and two different energy levels (trial A, 16.9 MJ and 18.2 MJ digestible energy (DE)/kg feed DM; trial B, 18.3 MJ and 20.1 MJ DE/kg DM). The same highquality protein concentrate was added to each ration in the scaled amounts. The amino acid (AA) content was determined in the whole carcass at the beginning (nine carp per trial, mean live weight 170 g) and end of the growth period (six carp per treatment, mean live weight 900 g in trial A and 1130 g in trial B). The increase of the CP content in the feed up to 41% caused a significant increase in the content of essential and non-essential AA (in % carcass DM). In contrast, the gradual increase of the energy supply, accompanied by a constant CP supply, caused an obvious decrease in the AA content. The AA composition of the carp protein (g AA per 16 g N) was not influenced by the differing CP and energy supply nor by live weight (at the start of the trial as compared to the live weight at the end). The following values ( g AA 16 g N ) and relative values (only essential AA, in comparison to Lys = 100) were obtained as mean AA composition ( n = 70): Lys 6.55 (= 100); Met 2.11 (32); Cys 0.68 (10); Trp 0.81 (12); Thr 3.95 (60); Leu 6.87 (104); Ile 3.73 (56); His 2.82 (43); Arg 6.02 (90); Phe 3.78 (58); Val 4.25 (65); Ser 3.97; Asp 9.21; Glu 13.23; Pro 5.44; Gly 7.94; Ala 6.34; Tyr 2.28. Significant deviations in the AA pattern of the carp proteins, as compared to the recommended AA contents in feed proteins, are seen particularly in the AA Leu, Ile and Arg.