Apparent digestibility coefficients of differently processed poultry and fish offal meals fed to the african catfish, <i>clarias gariepinus</i> (burchell, 1822) juveniles

Abstract

Waste from poultry and fish processing plants whose disposal presently raises a major environmental concern may be a source of animal protein in fish diet, if properly processed. This study was carried out to determine the nutrient composition and apparent digestibility coefficient (ADC) of nutrients in differently processed poultry and fish offal in diets fed to Clarias gariepinus. The test ingredients were autoclaved poultry offal (P1), oven-dried poultry offal (P2), poultry offal paste with wheat offal as carrier (P3), autoclaved fish offal (F1), oven-dried fish offal (F2) and fish offal paste with wheat offal (F3). A 35 % crude protein (CP) reference diet (R) was formulated. Test diets contained 70 % reference diets and 30 % of test ingredients, with chromic oxide as the inert marker. Triplicate groups of C. gariepinus (5.50 ± 0.50 g) were fed diets for 8 weeks. CP content in ingredients was significantly high (p<0.05) in P2 (56.88 ± 0.00 %), with the lowest values recorded in F3 (35.00 ± 0.03 %) and P3 (31.50 ± 1.20 %). Linoleic and arachidonic acids were recorded in all fish offal meals, while only oven-dried poultry offal meal had arachidonic acid. ADC of nutrients varied significantly across treatments (p<0.05). ADC of CP was significantly highest in P2 (83.36 ± 0.49 %) and least in P1 (56.06 ± 0.36 %). ADC of phosphorus increased from 74.31 ± 0.55 % in P3 to 99.57 ± 0.75 % in P1. The result of this study revealed that nutrient digestibility by C. gariepinus was best in oven-dried meals compared to treatment methods.