The nutritive values of yeast grown on hydrocarbon fractions for broiler chickens. Poultry Sci. 50: 1022-1029. by research and teaching institutions in the country. The American catalogue, prepared by Dr. Ralph Somes, University of Connecticut, is under r

ABSTRACT Samples of yeasts produced on different hydrocarbon feedstocks with variations in methods of processing were evaluated as sole protein sources in chick diets. Net Protein Utilization (NPU) and Nitrogen Efficiency Ratio (NER) values were determined as relative index of quality in comparison to an isolated soybean protein. All diets were supplemented with 0.3 % DL-methionine so as to place emphasis upon the value of the other essential amino acids. NPU values for the yeast samples ranged from 40.8 to 73.5 in comparison to a value of 85.5 for the soybean protein. NER values ranged from 4.91 to 15.55 for the yeasts in comparison to 19.70 for the soybean protein. A large portion of the nitrogenous fraction of the yeasts is not in the form of amino acids which tend to downgrade the value of these products when compared on the basis of total nitrogen. POULTRY SCIENCE 54: 1129-1133, 1975 SINGLE cell protein derived from bac-teria, yeast, algae and fungi have the potential to provide low-cost protein supple-ments for the alleviation of amino acid mal-nutrition and to become major constituents of animal feeds. Feeding trials have demon-strated that yeasts grown on hydrocarbon feedstocks are palatable, non-toxic, and sat-isfactory sources of protein when properly blended with other commonly used feedstuff s in diets for pigs, chicks and laying hen