Yeast cell wall and live yeast products and their combination in broiler diets formulated with weekly ingredient variations.

A 6-week broiler study was conducted to evaluate whether subjecting the intestinal microflora of broilers to the effect of weekly variations in feed ingredients could be ameliorated by the inclusion of yeast-derived feed additives: a yeast cell wall extract (YCW), live yeast culture (LY) or their combination (YCW + LY). Recent changes in ingredient prices have motivated producers to formulate diets not necessarily based primarily on corn and soya bean meal. Intestinal microflora in birds can vary significantly based on the ingredient composition of their diet, and the make-up of the flora can influence overall bird performance. Within the three nutrient phases of this study, birds were fed either a traditional corn-soya ingredient profile or a variable-ingredient regimen, which had weekly changes in the ingredient composition. There were consistent ameliorative effects of the yeast treatments in both the corn-soya and the variable-ingredient groups throughout all 6 weeks, with the YCW + LY combination showing a reduced effect when compared to either product fed alone. The effectiveness of YCW and LY on ameliorating the effects of weekly ingredient variations appeared most effective during the starter and grower phases, but was less significant during the sixth week. Journal of Animal Physiology and Animal Nutrition