Evaluation of Protein Digestibility and Nitrogen Fraction of Dried Food Waste for Swine Feedstuff

Abstract

The purpose of this study was to evaluate protein digestibility of dehydrated food waste manufactured by various methods for swine feed. Exp. 1. The effect of heating temperature (60°C, 80°C, 100°C, 130°C) and its duration (3hours, 8hours) on the nitrogen (N) digestibility of food wastes (TOFU cake, breads, rye bran, vegetables, TOFU and ABURA-AGE) was determined by in vitro method using pepsin and pancreatin. There was an interaction (P<0.001) between temperature and duration on in vitro N digestibility. Exp. 2. Relationship between in vitro N digestibility and N fractions based on Cornel net carbohydrates and protein system (CNCPS) was determined in various dehydrated food wastes (n=19). Dehydration methods applied were 1) dehydration by frying in oil under reduced air-pressure, 2) dehydration by fermentation at high temperature, and 3) dehydration by hot air. N digestibilities under these treatments were generally lower than those of conventional feedstuffs (n=17) such as corn, soybean meal, wheat bran, white fish meal etc. Food wastes that were dehydrated by frying in oil under reduced air-pressure contained high acid detergent insoluble protein (C fraction). The relationship between in vitro N digestibility and neutral detergent insoluble N fraction (B3+C fraction) showed negative correlation (r=-0.842, P<0.01). It is suggested that B3+C fraction can be used as parameter to predict the protein digestibility of dehydrated food wastes.