APPARENT DIGESTIBILITY COEFFICIENTS OF DIFFERENTLY PROCESSED POULTRY AND FISH OFFAL MEALS FOR AFRICAN CATFISH Clarias gariepinus (Burchell, 1822) JUVENILES

Résumé

Wastes from poultry and fish processing plants whose disposal presently raises a major environmentalconcern may be a source  of animal protein in fish diet, if properly processed. This study was carried out to determine the apparent digestibility coefficients (ADCs) of nutrients in differently processed poultry and fish offal for Clarias gariepinus. A reference diet (R) was formulated to contain 40% crude protein. Test diets contained 70% reference diets and 30% of test ingredients, with chromicoxide as the inert marker. The  test diets were poultry offal paste with wheat offal as carrier (P1), ovendried poultry offal  (P2),autoclaved poultry offal (P3), autoclaved fish offal (F1), oven-dried fish offal (F2) and fish offal paste with wheat offal (F3). A total of 315 African catfish, Clarias gariepinus juveniles (average weight; 5.50±0.50 g) were randomly distributed into 21 plastic tanks of dimension 0.42m x 0.29 m x 0.25m at 15 fish per tank. Diets R, P1, P2, P3, F1, F2 and F3 were fed to triplicategroups of fish twice daily at 5%  body weight for 8 weeks and excess feed siphoned out 30 minutes after each feeding. Faecal collection was done 8 hours after every feeding and pooled for eachtreatment for chemical analysis.  Apparent Digestibility Coefficients of nutrients varied significantly across treatments (p<0.05). ADC of crude protein was highest in F3, fish offal paste/wheat offal (78.63%) and lowest in F1, Autoclaved fish offal (65.83%). ADC lipid was highest in F3 (81.37%) followed by F2, oven dried fish offal (80.54%) and F1 (73.94%). ADC of phosphorus was highest in F2 (97.27%) followed by F3 (86.71%) and least in F1 (81.27%). The result of this study reveals that fish offal subjected to oven drying and the one blended with wheat offal showed high nutrient digestibility and therefore, can be utilized as protein source in the diets of Clarias gariepinus.