91 Late-Breaking: Towards sustainable alternatives to antibiotics. 2: The evaluation of an active dried yeast in the diets of finishing steers on feedlot performance rumen pH and liver health.

摘要

The objective of this study was to determine the effects of supplementing active dried yeast (ADY) on ruminal pH, feedlot performance, and liver health of feedlot cattle. Steers (n = 120) were blocked by weight and allocated to one of four pens in an automated intake feeding system. A re-sort on d 70 resulted in four final treatment assignments, following a Balaam’s design: steers fed control diet before and after the re-sort (CC; n = 30), steers fed control before and ADY after the re-sort (CY; n = 30), steers fed ADY before and control after the re-sort (YC; n = 30), and steers fed ADY (YY; n = 30). Sixty steers received indwelling rumen boli to monitor ruminal pH during dietary transition (d 56 to 106) from low to high concentrate. Ruminal parameters were analyzed as a repeated measures design. Feedlot performance traits (ADG, DMI, G:F, residual feed intake) were not affected by treatment (P ≥ 0.36). Mean ruminal pH was highest for CC and YC, intermediate for YY and lowest for CY (6.26, 6.23, 6.19 and 6.09, respectively; P = 0.0587). Acidosis bout prevalence and duration was greatest for the CY group (P = 0.0056). However, ruminal pH values of CC and YC steers drifted further from basal values than CY and YY steers during dietary transition (P = 0.0053). The number of days experiencing bouts (DEB) of acidosis was inversely related to performance traits ADG (P = 0.0340) and G:F (P = 0.0360). There was no treatment effect on liver abscesses prevalence (P = 0.3515) or severity (P = 0.3431). There was no relationship between DEB and liver abscess severity (P = 0.9008). There is evidence to suggest that the addition of ADY in the diets of beef cattle may aid in ruminal stabilization during dietary transition.