Inclusion of sun dried brewer’s spent yeast to improves nutritive value, in vitro digestibility and rumen degradability of wheat straw

Abstract

Dry brewery spent yeast has high protein (43.5% CP) and metabolizable (14.3 MJ/kg DM) contents and it is an effective animal feed. Therefore, this study aims to evaluate the chemical composition, invitro digestibility, and in situ degradability of sun-dried brewer’s yeast and wheat straw. Liquid brewer's waste yeast (BSY) and water were mixed at ratios of 1:5 each, respectively. The mixed debris was immersed for 7 hours in a 200-litter plastic bucket. The material was placed in a fixed location and given time to allow the biomass (residues) to settle in the foundation of the materials. Water accumulated above the biomass was easily removed by tilting the container after the BSY had been soaked with water. After washing the floor to get rid of any dust, the biomass was poured over the area to dry. After three days of sun drying, the dried brewery yeast was collected and removed by using a scraper. The dry spent yeast (DY) and wheat straw (WS) was milled (1-2mm) and mixed uniformly. Six treatments were made with different rates (DY0, DY10, DY20, DY30, DY40, and DY50 for DY: WS at 0:100, 10:90, 20:80, 30:70, 40:60 and 50:50, respectively) on a dry matter (DM) basis. Three cannulated Boran-Friesian steers with average body weight (480 kg) and age(42 months) were used to incubate samples for 6, 12, 24, 48, 72, and 96 hours. The nylon bags were 6.5 by 14 cm and had a 50 µm pore. Ash, crude protein (CP), digestible organic matter in the dry matter, estimated digestible protein, and metabolizable energy contents were increased in proportion to dry yeast inclusion increased, while all fiber fractions were declined (P < 0.01). Chemical composition of wheat straw is improved by the addition of dry yeast (50%) and raising the concentrations of Ca, P, Cu, and Zn (P < 0.01) while lowering the other minerals (K and Fe). As dry yeast inclusion increased, the kinetics of DM, CP, and neutral detergent fiber (NDF) breakdown similarly accelerated (P < 0.01). Therefore, we advise limiting the use of wheat straw can be improved with the inclusion of dry brewery spent yeast. However, feeding experiments are needed to verify the context of animal performances and economic returns.