Yeast cell wall supplementation alters the performance and health of beef heifers during the receiving period1,2

A study was designed to determine the effect of feeding yeast cell wall (YCW) on performance of newly received crossbred heifers (n = 140; 225 ± 9.4 kg). Heifers were sorted by source (n = 2) and arranged in a completely randomized block design (35 pens; 7 pens per treatment; 4 heifers per pen). Heifers were separated into treatments [control (CON), YCW A (2.5 g/d per head), YCW AA (5.0 g/d per head), YCW B (2.5 g/d per head), or YCW C (2.5 g/d per head)] and fed for 56 d. Daily DMI and individual BW (every 14 d) were collected. On d 56, cattle from treatments CON, YCW A, and YCW C (21 pens; 7 pens per treatment; 4 heifers per pen) were fitted with vaginal temperature (VT) recording devices. On d 63 cattle were weighed and challenged with a s.c. dose (0.5 μg/kg of BW) of lipopolysaccharide (LPS). A final BW was collected and VT devices were removed after 14 d. A significant source × treatment interaction was detected, and data were separated accordingly. In source 1, YCW C heifers exhibited greater BW at d 42 and ADG from 0 to 42 d compared with all other treatments (P = 0.02 and P < 0.01). In source 2, an increased linear effect for YCW A was detected for BW, ADG, and G:F from d 0 to 14. Following the s.c. LPS challenge, source 1 YCW C heifers exhibited greater ADG (P < 0.01) and G:F (P = 0.01) compared with CON. In source 2, no significant differences in performance were observed after LPS (P > 0.62). There was an increase in VT in all treatments after LPS (P < 0.01), with YCW C maintaining greater VT after LPS than CON and YCW A (P < 0.05) for both sources. These results suggest that YCW supplementation can improve ADG and DMI during the receiving period and affect the physiological response to a mild endotoxin challenge during moderate to severe heat stress.