Replacement of soybean meal in the diets of African catfish fingerlings using Avocado seed meal fortified with DL-Methionine

Abstract

This study evaluated the effects of the replacement of soybean meal with methionine fortified avocado seed meal on the biochemical, proximate composition and growth performance of African catfish, Clarias gariepinus. Five diets were formulated to contain 0%, 25%, 50%, 75%, and 100% of avocado seed meal fortified with (0%, 0.20%, 0.40%, 0.80%, 1%) methionine (Met) respectively, in the replacement for soybean meal. African catfish fingerlings (9g-10.5g) were stocked randomly into 15 glass tanks (75cm   X 60cm X 60 cm) at 15 fish per tank, and fed the experimental diets to apparent satiation twice daily for 56 days. Results indicated that the fish fed diet of 25% avocado seed meal fortified with 0.02% Met had the best growth performance in weight gain, feed conversion ratio (FCR) and specific growth rate (SGR), though not significantly (P>0.05) different from the values obtained from fish fed diet with 100% soybean meal and 50% of avocado meal fortified with 0.40% Met. Blood profile revealed that avocado meal fortified with Met significantly improved the pack cell volume, without significantly affecting red blood cells, white blood cells and haemoglobin concentrations. Carcass proximate composition expressed that dietary avocado and Met significantly improved the fat and total ash composition while the nitrogen free extract was significantly reduced. Carcass minerals 
showed that feeding fish with diets of avocado meal with Met significantly increased the Mg, Ca, P and Zn depositions in the fish. In summary, the study established that avocado seed meal fortified with 0.4% DL-methionine can effectively replace up to 50% of soybean meal in the diets of African catfish.