Effect of fungal fermentation on proximate composition and <i>in vitro</i> performance of agrowastes used in animal feed

Abstract

Large quantities of agricultural wastes generated annually from the processing of agricultural produce are disposed of indiscriminately in the environment, thus contributing to environmental pollution. Value addition to cassava (Manihot esculenta Crantz) peels, and a mixture of yam (Dioscorea spp.) and plantain (Musa paradisiaca) peels, which accumulate during manual peeling will help reduce this environmental impact in addition to being a source of income. The effects of fungal fermentation on their proximate composition and suitability for use as enriched animal feed were thus investigated in this study. Cassava peel and yam-plantain peel mixture were each o fermented with Aspergillus niger and Trichoderma spp. at 32 ^oC at moisture content of 52% and 60% respectively for a week and the potential of the biomass was investigated in feeding trials of Wistar rats over a four-week period. After sacrifice, their sera and vital organs were analysed for key enzymes and metabolic products. It was observed that Aspergillus niger-fermented cassava peel (FCP) was the best treatment with increased protein content (from 6.73% to 19.3%) due to microbial biomass. While the carbohydrate content decreased following fermentation, the calorific value remained similar to that of the raw peel. No mortality was recorded in the experimental rats fed the FCP and standard commercial feed (CF) while 100% mortality was th observed by the 4^th week in the control group fed unfermented cassava peel (UCP). Organ-body weight ratio and some biochemical parameters e.g. cholesterol, high density lipoprotein (HDL), urea of FCP-fed rats were similar to those of the CF group. Lower amounts of some markers e.g. aspartate transaminase (ALP) and alanine transaminase (AST) were observed relative to UCP group. This research demonstrates the potential of microbially-detoxified food waste to replace commercial feed as a cheap alternative with minimal undesirable physiological effects in the animal models.

Keywords: Fungal Fermentation; Plantain Peel; Yam Peel; Food Wastes; Aspergillus niger; Wistar Rats