Available Energy of Yeast Grown on Various Carbon Sources by Growing Chicks

Abstract

Available energy of 4 yeasts grown on hydrocarbon in 4 different companies in this country and 2 yeasts grown on sulfite-pulp waste liquor in a company was estimated by bioassay procedure, using total 560 meat-type one-day-old chicks of both sexes. Cellulose, soybean oil, yellow corn and soybean meal were used as standard materials, of which metabolizable energy was 0, 9.21, 3.48 and 2.28kcal/g air-dry matter.Nitrogen-corrected metabolizable energy and digestibility of crude protein of these yeasts were also determined, collecting excreta for 2 days from 26 days of age.Available energy estimated on body weight gain per unit of feed taken, i. e. feed efficiency at 4 and 8 weeks of age, and metabolizable energy estimated by analyzing the excreta chemically were quite agreeable, suggesting the reliability of the procedures to determine both of available energy and metabolizable energy.The highest caloric value of 3.38kcal/g dry matter was obtained on Yeast A grown on hydrocarbon. The calolic value of yeasts grown on hydrocarbon was different among 4 samples, but the value was higher than that of the yeasts grown on sulfite-pulp waste liquor.Digestibility of crude protein of the yeasts grown on hydrocarbon was excellent and almost constant, being 84% in average.Highly significant correlation was observed between caloric value and crude protein content of 6 yeast on dry-basis, while the correlation was not significant between caloric value and gross energy content. The findings, as well as that of excellent digestibility of yeast protein, suggest that the protein content of yeast may be an useful indicator to evaluate nutritive value of yeast roughly.