Two experiments were conducted to determine the effects of a fibrolytic enzyme pretreatment on growth performance, apparent total tract digestibility, and ruminal pH throughout the grower and early finisher period (Exp. 1), and to examine the impact of Saccharomyces cerevisiae supplementation on intake, performance, and indicators of gut health in the late finisher period (Exp. 2). Fifty-four steers were randomly assigned to a subgroup determining experimental treatment groups. In Exp. 1, steers were randomized to: control (CON1; no enzyme) or enzyme (ENZ; 0.75 ml kg-1 DM of feed) dietary treatments. Digestibility was improved (P≤0.05) in ENZ steers for DM, CP, NEg, and sugars, but did not affect (P≥0.12) DMI, ADG, or reticulo-ruminal pH. In Exp. 2, the treatments were: control (CON2; no yeast) or yeast (YST; 3.0 g animal-1 daily) supplemented diets. Rumen papillae were collected for mRNA expression of gut barrier function (OCLN, CLDN, ZO1, ZO2) and immune response (TLR2, TLR4, FCAR) genes and histological measurements. YST decreased (P<0.001) DMI by 31%, reduced variation in dry matter intake, and improved feed conversion ratios, but did not impact rumen health mRNA expression or histology measures (P≥0.07). Overall, ENZ improved the digestibility of some nutrients in the grower period, and YST improved feed efficiency, without impacting growth performance or gut health.
Dietary Supplementation of Mixed Yeast Culture Derived from Saccharomyces cerevisiae and Kluyveromyces maxianus: Effects on Growth Performance, Nutrient Digestibility, Meat Quality, Blood Parameters, and Gut Health in Broilers
