Effect of a multielement trace mineral injection before transit stress on inflammatory response, growth performance, and carcass characteristics of beef steers.

Weaned calves (n = 98; 256 ± 11.5 kg) were used to evaluate the impact of improving trace mineral (TM) status using a multielement TM injection 28 d before transit on markers of inflammatory and stress responses in response to transit and postshipping growth performance. On d 0 of a 28-d preconditioning program, calves received subcutaneous TM injection (MM; n = 48) containing 15, 10, 5, and 60 mg/mL of Cu, Mn, Se, and Zn, respectively, or physiological saline injection (SAL; n = 48). On d 28, steers were weighed, half of the steers from each treatment were transported for a 20-h transit stress period (SHIP; n = 24 per injection treatment), and half of the steers were returned to their pens for 20 h of feed and water restriction without transit (NOSHIP; n = 24 per injection treatment). The SHIP steers were unloaded on d 29 and all steers (SHIP and NOSHIP) were immediately weighed and sorted into new pens (n = 4 steers per pen) for the growing period. At the start of finishing (d 113), steers received a second MM or SAL, resulting in a 2 × 2 × 2 factorial (n = 12 steers per treatment combination). Samples of blood were collected on d 28, 29, and 34 and liver on d 22 and 40. The initial MM increased liver Cu, Se, and Zn concentrations of cattle (P ≤ 0.02) but did not affect ADG during preconditioning (P = 0.89) or BW shrink as a result of transit (P ≥ 0.52). Plasma Fe concentrations were decreased after the transit stress period in SHIP calves (P ≤ 0.05) relative to NOSHIP calves but recovered 5 d after transit, and serum IL-8 concentrations were greater in SAL-SHIP steers than MM-SHIP steers (P = 0.04). Altering TM status through MM caused steers to have lesser ADG (P = 0.03) during the 14-d period after transit (d 29 through 43) but did not affect growth during the growing period (d 5 through 112; P ≥ 0.40). Minimal effects on finishing performance and carcass characteristics were noted, but there was a 3-way interaction (P ≤ 0.02) in which SAL-NOSHIP-MM steers had the greatest yield grade (YG) and smallest ribeye area (REA) and SAL-SHIP-MM steers had the least YG and largest REA. Overall, a MM 28 d before transit or before feed and water restriction did not affect the inflammatory response or plasma TM concentrations but decreased ADG in the 14-d period after transit. Trace mineral injection had limited effects on overall growth performance and carcass characteristics, likely because steer initial TM status was well within the adequate range. [ABSTRACT FROM AUTHOR]