|dc.description.abstract||Three separate loads of beef heifers (n = 277 heifers) were transported to the Texas Tech Burnett Center in New Deal, TX to examine the effects of a yeast supplement (Levucell SB yeast; Lallemand Animal Nutrition, Milwaukee, WI) on health and performance of feedlot cattle. In Load 1, 91 beef heifers (average BW = 223.5 kg) were shipped 1,403 km from an order buyer facility in Meridian, MS. On arrival, cattle were weighed and processed and assigned randomly to one of two treatments (five pens per treatment) during a 35-d receiving period: 1) Control (C) = a 65% concentrate receiving diet; or 2) Yeast (Y) = a 65% concentrate receiving diet with Levucell SB yeast added to supply 0.5 g of yeast/(heifer•d). Diets were changed to 72% concentrate on d 21 to 35. Following processing, cattle were moved to their assigned pens and fed their respective diets ad libitum once daily at 0800. Cattle were observed daily for symptoms of bovine respiratory disease (BRD) and treated as needed when rectal temperature was > 39.7 °C. Loads 2 and 3 (93 heifers each; average BW = 223.5 kg and 226.1 kg respectively) were processed and assigned to treatments and pens as described for Load 1. Averaged over the three loads, feeding Levucell SB yeast did not affect the overall (P > 0.12) dry matter intake (DMI) or average daily gain (ADG) during the 35-d study. Although, numerical advantages in ADG for the Y treatment were evident from d 0 to 14 and 0 to 28, changes in ADG were inconsistent among the three loads. As with ADG, concentrate DMI for the various measurement periods did not differ between treatments, but a trend was evident for a slight increase from d 0 to 35 in concentrate DMI for the Y vs. C treatment for Loads 1 and 3, but not with Load 2. Because treatment effects on ADG and DMI were not significant, G:F did not differ between treatments. Within loads, no differences (P = 0.21 to 0.28) were noted for the percentage of cattle treated once or more for BRD; however, a consistently smaller proportion of the cattle in the Y treatment group were treated compared with those in the C group. Thus, averaged over the three loads, an increase (P = 0.04) in the percentage of C heifers treated once or more compared with Y heifers (24.0 vs. 13.78% respectively) was observed. An odds ratio of 1.99 for C vs. Y indicated that C heifers were approximately twice as likely to be treated once or more for BRD than were Y heifers.
From the results of the three loads of newly received heifers used in this experiment, the addition of 0.5 g/heifer daily of Levucell SB yeast to the diet of newly received cattle plus oral dosing of approximately 1 g/heifer at the time of arrival processing resulted in fewer heifers being treated for BRD. The feeding of Levucell SB yeast during the receiving period had limited effects on performance of the 277 heifers used in the experiment.||