Evaluation of methanol‐grown bacteria and hydrocarbon‐grown yeast as sources of protein for poultry: Performance of broilers during the finishing period

Three trials were carried out with male broilers during the 5‐ to 8‐week period, for the evaluation of two types of single‐cell protein (SCP) in practical‐type broiler finisher diets. The SCP tested were: Pruteen, produced from methanol‐utilising bacteria, and a Lavera‐type yeast which utilises the normal paraffins of heavy gas oil. 2. The inclusion of 90 to 100 g of either type of SCP/kg of the diet caused a 2 to 3% reduction in weight gain, a 3 to 5% decrease in food consumption, and up to a 2% improvement in food utilisation. The reduced growth rate could be fully explained by the decrease in food intake, with essentially no effect on food : gain ratio. 3 In diets containing Pruteen, arginine was second limiting after the sulphur amino acids. 4 An odd‐numbered fatty acid (17 carbons, unsaturation unknown) of Pruteen was not found in the carcass lipids of broilers fed on a diet containing 120 g Pruteen/kg.