Growth performance and body composition of Oreochromis niloticus fed different levels of maize grain.

Growth performance and body composition of Oreochromis niloticus fingerling (average initial weight 7.69  0.25 g) fed isoenergetic diets containing 25.0, 29.5, 34.0, 38.5 and 43.0 percent of maize grain for a period of 98 days were studied. Although, no significant differences were observed in the feed consumption of fish on different diets, the weight gain as well as the specific growth rate (SGR, as percentage of body weight gain per day) of fish decreased (p0.05) with the increasing level of maize grain in the diets. The feed conversion ratio (FCR, Kg feet consumed per Kg weight gain) for different diets differed (p0.05) and the best FCR value (1.68) was observed for diet containing 25 per cent maize grain. The protein efficiency ratio (PER, as g liveweight gain per g protein consumed) and net protein retention (NPR, as [increase in carcass protein/protein fed] x 100) values did not differ (p 0.05) with the increasing level of maize grain. The dry matter, fat and gross energy contents of fish carcass in the experimental groups decreased significantly as compared to initial body composition (fish slaughtered at the beginning of the experiment). The dry matter and fat contents increased with increasing level of maize grain. The level of maize grain however, did not affect (p0.05) the crude protein, ash and gross energy contents of fish carcass. The role of carbohydrate level in fish diet is discussed