Evaluation of certain substances as growth-promoting agents for the prawn Penaeus indicus

Seven substances, namely oxytetracycline (antibiotic), ethyloestrenol (synthetic steroid), thyroid (hormone), alfalfa extract (plant material), glucosamine (chemical), prawn shell (animal material) and testosterone (hormone), were selected for evalution as growth promoting agents to add in the diet of the prawn Penaeus indicus. These substances each was incorporated in a purified diet consisting of casein, starch, sucrose, cod-liver oil, cholesterol, vitamins, minerals and cellulose. The diets supplemented with testosterone, glucosamine, prawn shell and alfalfa extract, respectively at levels 2.5 mg, 0.8 g, 0.8 g and 2.0 ml per 100 g of diet, produced faster growth, higher survival and better food conversion ratio than the control diet did. Testosterone gave the best results, the other substances in the order of efficiency being glucosamine, prawn shell and alfalfa extract. The diets supplemented with oxytetracycline, ethyloestrenol and thyroid, respectively at levels 10 mg. 0.5 mg and 1.0 mg per 100 g of diet, gave no better result in growth, survival rate and food conversion ratio than the control. Presenting the details ot the evaluation results, the effect of these seven substances on the body composition of the prawns is discussed