Effects of Graded Methionized Yeast on the Growth, Nutrient Utilization, and Hematobiochemistry of Hybrid C. gariepinus x H. longifilis (Hetroclarias)

Abstract

Sacharomyces cerevisiae contains about 45% protein but lacks some essential amino acids like methionine. Methionine promotes the growth of yeast and inhibits autophagy. We methionized yeast for 48hrs at 28°C and thereafter used it in the formulation of novel diets for hybrid African catfish `heteroclarias`. The diets varied in the inclusion of methionine: Sacharomyces cerevisiae as follows; F1, 0:250; F2, 200:50; F3,150:100; F4, 100:150; F5, 50:200, and F6, 250:0. Hybrid catfish were stocked at 20 fish per aquaria, subjected to 12D:12L photoperiods and were fed ad libitum for 86 days. Hybrids that received feed F5 (200gyeast:50g Meth), had the highest SGR, 2.86±0.05 % day-1, lowest FCR F2, 1.04±0.08, highest weight gain 264.96±0.73g, highest PER 5.92±0.07 and highest DFI of 2.95±01g day-1. Conversely the hybrid fed diets F2 (200gMeth:50g yeast), had the lowest SGR of 0.97±0.01% day-1, highest FCR of 2.53±0.01, lowest weight of 35.03±7.52g, lowest PER 0.80±0.02 and lowest DFI of 0.47±0.02g day-1. All analyzed hematobiochemical indices were optimal for catfish fed F5 (200gyeast:50g Meth) and poorest for those fed F2(200gMeth:50g yeast). Results suggest that 50g kg-1 methionine inclusion and methionization of yeast is optimal and yields best growth, nutrient utilization and hematological parameters in diets of hybrid African catfish.