Effect of palm kernel on the nutrition of tilapia fingerlings (Oreochromis niloticus)

Objective. To determine the response of the productive indicators when including palm (Elaeis guineensis) kernel cake (PKC) in diets for the nutrition of tilapia fry (Oreochromis niloticus). Material and methods. Three hundred sex-reversed males of tilapia (4.89 +/- 0.09 g) were used and distributed according to a completely random design for 60 days, in three replicates per treatment (20 fish per replicate). The PKC was used to formulate five diets isoproteic (30.64%), isolipidics (7.38%) and isoenergetic (11.84 MJ kg(-1) of feed), control (T0), 5% (T5); 10% (T10); 15% (T15), and 20% (T20). Results. Fish fed T0, T5, and T10 treatments did not show statistical differences among groups (p > 0.05), but yes with the T15 and T20 in the overall nutrient digestibility, growth, and body composition. However, the inclusion of up to 20% PKC in the diet decreased the feed cost. There is a high dependency degree between the neutral detergent fiber (%) and the apparent dry digestibility (%) and apparent protein digestibility (%) (R-2 = 0.732 and R-2 = 0.774; p < 0.000), respectively. Conclusions. The palm kernel cake can be used up to 10% on tilapia fry diets without affecting apparent nutrient digestibility, growth, and whole-body nutritional contents. The progressive inclusion of PKC in the diets decreased the feed cost for more profitable tilapia culture.