Total sulphur amino acid requirement of the Indian major carp, Labeo rohita (Hamilton)

The quantitative dietary sulphur amino acid requirement of the Indian major carp, Labeo rohita (Hamilton), was determined by conducting a growth study. The experimental diets contained 400 g crude protein kg−1 from casein, gelatine and supplemental crystalline amino acids. Diets containing six graded levels of methionine (3.2, 6.5, 9.0, 11.5, 14 and 16.5 g kg−1) with a constant level of cystine (1.4 g kg−1) were formulated and fed to triplicate groups of Labeo rohita fingerlings twice a day to satiation for 60 days. The optimum dietary requirement for methionine was estimated using the break-point regression analysis at 11.5 g kg−1 of diet or 28.8 g kg−1 of dietary protein. Thus the total sulphur amino acid (Met + Cys) requirement was determined to be 12.9 g kg−1 of diet or 32.3 g kg−1 of protein. Higher survival, specific growth rate and food conversion efficiency values were observed for fish fed the diet containing optimum levels of sulphur amino acids.