The effect of different dietary levels of an‐paraffin‐grown yeast on the growth and food intake of broiler chicks

Synopsis Sixteen groups, each of about 30 male or female Ross 1 chicks, were given pelleted diets containing 0, 5, 10 or 20% yeast in place of herring meal. The diets were given from 1 d of age for 4 weeks; from 4 to 8 weeks the birds were given a common broiler finisher diet. Replacing up to 10% herring meal by yeast did not significantly affect live‐weight at 4 weeks of age but food conversion efficiency was poorer with the diet containing 10% yeast. Birds given the diet containing 5% yeast to 4 weeks of age were significantly heavier at 8 weeks. The diet with 20% yeast significantly depressed growth at 4 and 8 weeks of age. The use of yeast in broiler finisher diets was investigated in a second experiment. Birds similar to those used in the first experiment were given diets containing yeast at levels of 0, 5, 10 or 20% from 4 to 8 weeks of age. Live‐weight at 8 weeks was not significantly affected by level of yeast in the diet; food conversion efficiency was significantly better with the 20% yeast diet. Blood plasma uric acid levels were not affected by the level of yeast in the diet.