Effects of casein coating on utilization of dietary amino acids by fingerling carp and channel catfish.

Abstract

A six week feeding study was carried out to elucidate the effects of casein coating on the utilization of crystalline amino acids (AAs) which had been supplemented to diets for carp and channel catfish fingerlings. The experimental diets were formulated to have similar essential amino acid (EAA) profiles, twtal AA contents, and other compositions to those of the control diet (25% casein and 10% gelatin). Both carp and catfish responded to the pH adjustment AA diet to a certain extent; coating the whole AA mixture with casein or the addition of 7.65% casein (total amount used to coat the mixture) to the AA mixture with pH adjustment improved growth and feed efficiency (FE) significantly in carp and almot four-fold in catfish. Addition of individually coated EAAs to gelatin instead of the uncoated EEAs improved growth and FE about four-fold in carp and almost three-fold in catfish. Also, addition of 2.5% casein (total amount used to coat the AAs) to gelatin with the uncoated EAAs improved growth and FE about three-fold in carp, but this treatment showed no significant effect in catfish. None of these treatment groups showed a performance comparable to that of the control groups. However, data from this study suggest that, in both species, utilization of an AA mixture could be improved by adding a certain amount of casein as well as couating the mixture with casein. Efficiency in utilization of EAAs supplemented to gelatin can be enhanced further by coating them individually with casein rather than by simply akking 2.5% casein.