THE EFFECTS OF A SUPPLEMENTAL PROBIOTIC-PREBIOTIC ON PERFORMANCE AND CARCASS CHARACTERISTICS OF NEWLY RECEIVED FEEDLOT CATTLE

Two hundred and fifty-eight (average BW = 250 ± 11.4 kg) crossbred steers were received at the Texas A&M AgriLife Research Feedlot in Bushland, TX. Steers (n = 240) were stratified by average initial BW (d-1, d-0) and allocated to 1 of 2 BW blocks in a randomized complete block design. Steers were offered 1 of 3 dietary treatments. The control treatment (CON) received a pellet without probiotic-prebiotic blend (P-PB). Treatment 2 received a pellet with P-PB from d 0 to 21 followed by the CON pellet from d 22 to 42 (P-PB21). Treatment 3 received the P-PB pellet from d 0 to 42 (P-PB42). Following the 42-d receiving period, the treatment pellets were removed and replaced with steam-flaked corn (SFC) for the remainder of the finishing period. If dry-matter intake (DMI) was < 6.35 kg/steer/d, the P-PB pellet was included at 8.75% of the diet. If DMI was ≥ 6.35 kg/steer/d, the P-PB pellet was included at 6.25% of the diet. Steer BW was measured on d 21 and d 42 of the feeding period. Continuous data were analyzed using the MIXED procedure of SAS, categorical data were analyzed using the GLIMMIX procedure. Pen was considered the experimental unit, block a random effect, and treatment a fixed effect. No treatment effects were observed from d 0 to d 42 for BW (P ≥ 0.91), average daily gain (ADG; P = 0.97), feed efficiency (P = 0.99), or dry matter intake (DMI; P = 0.95). No treatment differences were observed for percent morbidity or mortality (P ≥ 0.38) from d 0 to 42. Supplemented P-PB did not impact longissimus area (LM), fat thickness, marbling score, USDA Quality or Yield grade (P ≥ 0.24), while
dressing percent (DP; P ≤ 0.05) and hot carcass weight (HCW; P = 0.09) were greatest for CON. While results remained similar between treatments, there were no negative effects on cattle health and performance during the receiving period.