EVALUATION OF RAPESEED MEAL AS AN ALTERNATIVE PROTEIN SOURCE IN THE DIETS OF GIFT TILAPIA CULTURED IN CAGES AT POONDI RESERVOIR, TAMIL NADU

Soybean meal (SBM) is a widely available protein source with nearly sufficient digestible protein, high energy content and good amino acid profile and used as a cost effective replacement feed ingredient to fish meal in aquafeeds. Increase in the use of soybean meal results in steady increase in its cost. Rapeseed meal is relatively less costly than soybean meal and the amino acid content is comparable well with that of soy bean meal.      

The evaluation of the efficiency of rapeseed meal (RSM) as an alternative protein source by replacing soybean meal (SBM) in the diets of GIFT strain of tilapia was carried out in cages installed at Poondi reservoir, Tamil Nadu. Five isonitrogenous (30% protein) and isolipidic (7% lipid) diets were formulated incorporating RSM protein by replacing SBM protein at 0 (control diet), 25, 50, 75 and 100% level (0RSM, 25RSM, 50RSM, 75RSM and 100RSM). Each diet was fed replicate groups of GIFT tilapia with a mean initial weight of 20.38 ± 0.0678 g for 60 days in cages. GIFT tilapia fishes fed with 75RSM diet attained maximum SGR (3.22), best FCR (1.03) and maximum PER (3.23). The fishes fed with 0RSM, 50RSM and 100RSM diets showed no significant difference (P > 0.05) in MWG, SGR, FCR and PER. It was concluded that, rape seed meal is an efficient fish feed ingredient that can be used to replace soybean meal in the diets of reservoir cage cultured GIFT tilapia without compromising growth, feed conversion ratio and whole body composition.