EVALUATION OF APPARENT DIGESTIBILITY COEFFICIENTS OF DIFFERENT DIETARY PROTEIN LEVELS WITH AND WITHOUT FISH MEAL FOR LABEO ROHITA

The apparent digestibility coefficients of three protein levels of reference diets (without fish meal) and test diets (with fish meal) were estimated for Labeo rohita. Three test diets (test diet-I, test diet-II and test diet-III) and three reference diets (reference diet-I, reference diet-II and reference diet-III) having 28, 30 and 32 % protein levels were prepared. Chromic oxide was used as an internal marker in the experimental diets for the evaluation of digestibility of protein levels. The differences in apparent digestibility for dry matter, crude protein, crude fat and gross energy of reference and test diets were highly significant (P<0.01). The apparent digestibility coefficients (ADCs) of dry matter were 32.10 ± 0.30 and 35.30 ± 0.30 % for reference and test diets-III. The ADCs of crude protein and crude fat were 77.92 ± 0.10, 69.23 ± 0.06 and 75.77 ± 0.05, 70.40 ± 0.22 % for reference and test diets-III, respectively. The values of ADCs of gross energy were maximum for reference diet-III (52.28 ± 0.25%) and test diet-III (48.65 ± 0.78%). The ADCs of dry matter were 19.80 ± 1.40 and 18.15 ± 0.05 % for reference and test diet-I. The ADCs of crude protein and crude fat were 73.93 ± 0.05, 68.43 ± 1.58 and 59.49 ± 1.13, 57.02 ± 2.42 % for reference and test diet-I respectively. The ADCs values of gross energy were for reference diet-I (42.43 ± 0.36%) and test diet-I (39.09 ± 1.35%). The better ADCs for dry matter, crude protein, crude fat and gross energy were at 32 % protein level