Document Type : Original Article
Department of Fisheries and Aquatic Sciences, Faculty of Agriculture and Forestry, Cross River University of Technology PMB 102 Obubra, Cross River State, Nigeria
A study was conducted to evaluate the effect of replacement of cod liver oil (CLO) by soybean oil (SO) on the carcass composition, haematology and sensory qualities of the flesh of the Nile tilapia Oreochromis niloticus. Four diets (30% cp) containing 6% of added CLO and/or SO were formulated. Diet 1 contained 6% of added CLO, Diet 2 had 4% CLO and 2% SO, Diet 3 had 2% CLO and 4% SO and Diet 4 had 6% SO. The diets were fed to triplicate groups of ten tilapia fingerlings (mean weight 10.06 ± 1.02 g) for 56 days. Results at the end of the trial showed that carcass quality of the Nile tilapia fed soybean oil diets was not affected. The viscerosomatic index (VSI) of fish fed experimental diets decreased with increasing percentage of soybean oil in the feed, but the hepatosomatic index (HSI) showed a trend that is the reverse of VSI. The gonadosomatic index (GSI) of fish showed variation between treatments, with the control diet having the highest value. The values of the blood parameters (i.e. Hct, Hb, Esr, Wbc, and Rbc) of fish fed different diets showed variability among treatments, but fish fed the control diet had lower values than those fed other treatments. There was no significant difference in most of the organoleptic properties of the flesh (general appearance, colour, taste, juiciness), except in the texture and aroma of fish fed Diets 1 and 4 on the one hand, and those fed Diets 2 and 3 on the other (p < /em> < 0.05). The results indicate that soybean oil can replace up to 100% of fish oil in diets for the Nile Tilapia O. niloticus, without adverse effect on organoleptic properties.