Effet de l'incorporation de farines de soja et de poisson dans l'aliment sur la croissance et les enzymes digestives de Penaeus vannamei

In order to improve the formulation of diets fed to reared Penaeus vannamei, the effects of soya bean and fish meals on the growth, survival, and the characteristics of the hepatopancreas and digestive enzymes of the species were studied. Four soya bean meal concentrations (0, 5, 15, 40%), four fish meal concentrations (0, 5, 15, 30%), two forms of soya bean meal and three fish meals of different geographical origin were tested. Experimental conditions were as follows: ten individuals were placed in each tank (0.5 m2 ) and two tanks were subjected to each treatment. Food was given twice a day (08-09.00 h and 19.00 h) at 10% of the initial weight each day. For biochemical analyses, nine individuals per treatment were used for the determination of the hepatosomatic ratio, proteins, proteases, amylases and trypsin. The results show that a high level of soya bean or fish meals in the diet strongly depresses growth without any apparent effect on the digestive enzymes or the hepatopancreas parameters. No effect of soya bean meal type or geographical origin of the fish meal was detected. The results suggest that the incorporation of both soya bean and fish meals in the diet should be restricted to low concentrations and only with the aim of diversifying the protein sources.