Effect of palm kernel meal (Elaeis guineensis, Jacq, 1763) in the diet on digestive transit and some serum parameters in Nile tilapia (Oreochromis niloticus, Linnaeus, 1758)

Abstract

As part of the continuation of the thesis work on the valuation of palm kernel cake in the diet of Nile tilapia, a study was carried out from March 7th to April 12th, 2018 at the Aquaculture Research and Development Unit of the University of Lome in Togo. It aims to  evaluate the digestive use efficiency of palm kernel cake (PK) in Oreochromis niloticus. So, two lots of 180 male Oreochromis niloticus; juvenile of 57.14 ± 4.43 g and adults of 144.04 ± 7.65 g were each randomly distributed in 9 recirculate system concrete tanks of 600 L, at 20 fish per tank, filled to 250 liters of water. They were fed two weeks with three isoprotein diets (32% crude protein) in triplicate, distributed manually three times a day at 2% of the fish biomass; standard fish feed Raanan (RA) and two diets containing 30% PK untreated (R3) or cooked in water for one hour (R3C). After a 2 days fasting, some fish were fed once again to satiety (8am). Then a sample of 6 fish per lot was euthanized in a clove solution. After blood sampling, the fish were dissected at 0h, 1h, 4h, 8h, 12h and 24h after feeding to measure blood and intestinal parameters. The results obtained show that raw PK is an unpalatable fibrous ingredient but well valued once cooked with a digestive improvement allowing good absorption of food micronutrients in both juveniles and adults. This absorption led to changing in the serum protein level for growth of fish and nitrogenous excretion in the form of urea. The cooking slowed the transit of the food into the digestive tract of tilapia, this can improve zootechnical performance of fish.