Evaluation of Supplemental Protein Sources for Broiler Chicks

Two chick growth assays were completed to evaluate cottonseed meal, single-cell protein (torula yeast) and dehulled soybean meal in various combinations. In all cases, ground yellow corn supplied 4% of the total dietary crude protein (23%) with the balance coming from supplemental protein sources under study. To simulate conditions in those parts of the world where crystalline methionine and lysine are not readily available or economical, no amino acid fortification was carried out. As the sole source of supplemental protein, soybean meal was far superior to the rest, but equal protein contributions from soybean meal and cottonseed meal or from soybean meal, cottonseed meal and single-cell protein resulted in weight gains similar to those obtained with soybean meal alone. Equal protein contributions from cottonseed meal and single-cell protein resulted in gains and gain/feed ratios considerably greater than those occurring when either of these ingredients was fed alone. With soybean meal-cottonseed meal combinations, chicks gained similarly when fed soy-cottonseed protein ratios of 1:0, 5:1, 2:1, 1:1 or 1:2, but gain/feed declined linearly as cottonseed protein replaced soy protein in the diet.