The objective was to determine if delivery method of organic trace minerals and Saccharomyces cerevisiae yeast culture product influence growth performance, feed efficiency, and hepatic trace mineral measures in newly-weaned steers. Crossbred steers (n = 192; 256 ± 14 kg) were used in a 49-d receiving experiment. Within 36h of weaning, steers were weighed, allotted to 24 pens (n = 8 steers/pen; 8 pens/treatment) and randomly assigned to treatments: traditional receiving diet (Con); traditional receiving diet plus the “stress-pack” directly in the diet (Force); traditional receiving diet plus a low-moisture, cooked molasses block fortified with the “stress-pack” (Tub). “Stress-pack” was offered the first 28 d of the 49-d. Biopsy samples were collected from a subsample of steers (n = 14 steers) on the day of weaning and subsequent samples were collected from the same steer (n = 1 steer/pen) on d 14, 28 and 49 for hepatic trace mineral concentration determination. A treatment × day interaction (P≤0.01) for hepatic Cu concentration was noted. Force had greater hepatic Cu (P≤0.05) compared to Tub and Con for the entire period. Tub had greater hepatic Cu compared to Con on d 14 and 28 (P < 0.05), but was similar to Con on d 49 (P>0.10). Force tended (P=0.08) to have greater DMI compared to Tub from d 1 to 14. From d 15 to 28, steers offered “stress-pack” had greater DMI (P=0.01) and tended (P=0.07) to have greater ADG compared to Con by 12.5%. From d 29 to 49, “stress-pack” steers had greater DMI (P=0.01) and Force consumed 6.9% more DM compared to Tub (P=0.01). Cumulative DMI (P=0.01) and ADG (P=0.05) was greater for Force compared to Tub by 5.4% and 9.4%, respectively. Application of “stress-pack” in diets offered to newly-weaned cattle enhanced production responses, but delivery method influences DMI and daily gain.

The objective of this study was to determine if supplementing encapsulated butyric acid and zinc (BZ) in lambs abruptly transitioned to a finishing diet has effects on growth performance, efficiency of dietary net energy utilization, and carcass traits following a 59.5 d finishing period. Polypay wethers (n = 32; initial shrunk BW = 39 kg ± 4.8 kg) were grouped by initial shrunk BW and assigned to dietary treatment (CON: 0 g BZ/kg diet DM; BZ: 2 g BZ/kg diet DM) in a randomized complete block design (RCBD) with pen (n = 16) as experimental unit. Wethers were abruptly transitioned from growing diet (based upon grass hay, dried distillers grains plus solubles, and a soybean meal based pellet; 1.65 Mcal/kg NEm, 0.95 Mcal/kg NEg) to finishing diet (based upon whole corn, soybean hulls, and a soybean meal pellet; 2.02 Mcal/kg NEm, 1.33 Mcal/kg NEg) upon study initiation. Lambs were harvested at the South Dakota State University meat lab and empty body measures and carcass traits were recorded. Growth performance was calculated on a shrunk live basis (BW × 0.96). Data were analyzed as an RCBD with fixed effect of treatment and random effect of block. No differences (P ≥ 0.15) were observed for final shrunk BW, ADG, DMI, feed conversion efficiency, observed-to-expected (O:E) DMI, O:E NEm, O:E NEg, EBW, dressed yield, or HCW. Percentage of boneless closely trimmed retail cuts (BCTRC) and red meat yield (RMY) were decreased (P = 0.03) for BZ vs. CON. Body wall thickness was increased (P = 0.02) for BZ vs. CON. Supplementing wethers BZ during an abrupt transition to a finishing diet had no effects on growth performance, efficiency of dietary net energy, or empty body measures and had minor effects on body wall thickness, percentage BCTRC, and RMY.