Poultry fat as a main fat source in a mixture to replace fish oil in diets for Oreochromis niloticus

The present work aimed to test poultry fat as the main fat source to replace fish oil in tilapia Oreochromis niloticus diets. For this purpose, a blend of poultry fat (71 %), kernel fat (PKF) (25 %) a rich source of lauric acid (12:0), and microalgae oil (4 %) rich in DHA and EPA was used to replace the fish oil. The isoproteic and isolipidic diets (37.5 % crude protein and 8 % crude lipids) contained four levels of the fat mixture in replacement of fish oil, 0, 1.65, 3.32 and 5 % in the total diet and were used to feed tilapia juveniles (6.04 ± 0.13 g) four times a day in triplicate groups. Six weeks later, all fish were individually weighted, and a strong correlation was found using a polynomial regression analysis showing a lower feed conversion ratio using a higher poultry fat mixture (r2=0.933), whereas a higher growth was registered (r2=0.762). The fatty acid analysis in the hepatopancreas showed no sign of lauric acid contained in the PKF and also indicated a significant reduction in oleic and linoleic acids, which were the main energy sources, whereas a substantial accumulation of palmitic acid 16:0 was observed. Further, the hepatosomatic index was significantly positive at higher amounts of poultry fat mixture (r2=1), revealing the capacity to maintain a higher weight in the hepatopancreas, despite there being no clear differences among the histology analyses obtained from the different dietary treatments. This study concluded that poultry fat can substitute fish oil from tilapia diets with a clear positive relationship with the overall performance of tilapia O. niloticus.