Evaluation of dietary protein levels for the growing Aorichthys aor (Hamilton 1822)
Anita Bhatnagar, Sushma, Oshin Dhillon
Dietary protein is one of the major determinants of fish growth, especially for the carnivorous economically important species like Aorichthys aor (Hamilton), for which lack of proper nutritionally adequate diet is the major constraint. In order to determine protein requirements for optimum growth, four diets with varying protein levels (35-42%) using processed soybean as the main protein source were formulated and fed to the fingerlings of A. aor for 90 days. Growth performance, nutrient retention and carcass composition were estimated. Studies revealed significant (P<0.05) increase in growth performance, accumulation of protein, fat and energy retention in the fingerlings fed on a diet containing 40% protein in comparison with the fish fed on other diets containing low or high protein levels. Ammonia excretion and o-phosphate production significantly low in fish fed on 40% dietary protein. The optimum dietary protein was found to be in the range of 40% when full fat processed soybean (@ 266g kg-1 of diet) is used as the main protein source in practical diets especially when stocking rates are high. Development of diets, reducing the excretion of ammonia and phosphate in the holding water may help in achieving better growth and nutrient retention.