The present study aimed to establish the basic knowledge for the formulation of specific diets suitable for African catfish Clarias gariepinus in the framework program of the development of a sustainable aquaculture in Burkina Faso. Indeed, in this Western African country, the major problem for fish farming remains the inaccessibility to adequate ingredients such as fish meal (FM) and fish oil (FO) because of their high cost. So, our main objective was to formulate a diet based on locally available agro-industrial by-products, covering the nutritional requirements of African catfish. To determine the best sources of vegetable oils that can effectively replace fish oil in the diet of African catfish, four iso-protein (40% crude protein), iso-lipid (10% crude lipids) and iso-energetic (17 KJ.g-1) in which FO was completely replaced by four vegetable oils (desert date palm oil: DO, cottonseed oil: CO, crude palm oil: PO, shea butter: SB) identified among the most locally available. The best results in terms of specific growth performance (SGR = 4.39% d-1) and bioconversion of EFA to AGLPI (ARA content and higher fads2 and elovl5 gene expression) were obtained with the DO diet. Regarding the determination of the optimal rate of FM substitution and the selection of the best agro-industrial by-products that can effectively replace FM in the diet of African catfish, three vegetable ingredients (groundnut oilcake: TA; sesame oilcake: TS; and moringa leaves meal: MM) were tested. Blood meal was used as animal protein source in each diet. Several regimes in which FM was gradually replaced (0, 25, 50 and 100%) with agro-industrial by-products were formulated. Our results showed that FM can be replaced up to 50% by the selected agro-industrial by-products without any detrimental effect on growth-related parameters. Regarding the amino acid (AA) composition of fish, although the levels of essential amino acids (EAA) decreased (p <0.05) progressively with the incorporation of agro-industrial by-products in the experimental diets, the EAA requirements of the species were covered. Growth, feed utilization, protein efficiency (PER), and the digestibility of dry matter and proteins were better in fish fed TS diets than those containing high levels of MM. In addition, the results demonstrated that, despite the decrease in SGR at replacing 75% of the FM by VM, the fish fed TS had a relatively higher SGR values (3.58% d-1) and their PER values (3.37) were better compared that of the control fish. Given the price of TS in Burkina Faso, this diet would be an good economic alternative in a country without direct access to fishmeal. All in all, the characterized agro-industrial by-products in the present research could partially or completely replace FM and FO respectively in the diet of the African catfish Clarias gariepinus, both in terms of growth and its biochemical composition, but more investigations are needed in order to determine the long-term impact of high levels of these vegetable ingredients on the reproductive efficiency and the fish fillet quality for human consumption needs.
|la date de réponse||20 mars 2019|
|Sponsors||Academie de Recherche et d'Enseignement Supérieur (ARES)|
|Superviseur||Patrick KESTEMONT (Promoteur), Aboubacar Toguyeni (Copromoteur), FREDERIC SILVESTRE (Président), Robert Mandiki (Jury), C. Rougeot (Jury), Geneviève CORRAZE (Jury) & Aurore Richel (Jury)|