Effect of dietary lipid source on the growth performance and body composition of Oreochromis niloticus

The study evaluated the growth performance and body composition of Oreochromis niloticus fed isonitrogenous and isocaloric diets containing different types of lipids (corn oil, olive oil, cod liver oil and beef tallow) at 14% level for a period of 65 days. Significant (P 0.05) differences were observed in the body weight gain, specific growth rate (SGR), condition factor, feed conversion ratio (FCR), protein efficiency ratio (PER), net protein retention (NPR), apparent net energy retention (ANER) and hepatosomatic index (HSI) values. The diet containing a mixture of all the 4 dietary lipids in equal proportions (3.5g of each lipid per 100g of diet) produced the best results (SGR, 1.73%; condition factor, 2.95; FCR, 1.27; PER, 2.06; NPR, 29.30% and ANER, 20.21%) whereas the diet containing beef tallow showed the poorest performance (SGR, 1.50%; condition factor, 2.76; FCR, 1.53; PER, 1.73; NPR, 26.26% and ANER, 18.53%). The growth performance of fish fed on diet containing beef tallow was however, significantly (P 0.05) better than that of lipid free diet. The diets containing corn oil, olive oil, and cod liver oil did not show any significant difference in the growth performance of fish. The hepatosomatic index (HSI) value increased in fish fed diets containing lipids (maximum 1.55% in case of corn oil) as compared to those fed lipid free diet (1.3 1 %). No significant differences were observed in the feed consumption of fish fed different diets. The type of dietary lipid significantly affected the body composition of fish. The data on the body composition of fish is very much correlated with the growth performance data. The fish fed on diets containing lipids showed higher body fat and crude protein but lower moisture and gross energy contents as compared to those fed lipid free diet. The fish fed on diet containing beef tallow however showed similar body protein and ash contents as those fed lipid free diet. The results of the present study suggest that diet supplemented with a mixture of different types of lipids will produce the best growth response in Oreochromis niloticus.