Injectable trace minerals in beef cattle

Abstract Text: Trace minerals (TM) support cattle growth, and mildly TM deficient cattle lose more weight during transit, have lesser ADG, and marbling scores. Trace mineral injection is a unique supplementation strategy, bypassing the gastrointestinal tract and rapidly improving TM stores. Ninety-eight weaned steers (256 ± 11.5 kg) were used to evaluate the impact of a multi-element TM injection prior to transit on performance, markers of the inflammatory and stress responses, and post-shipping growth performance. On d 0 of a 28 d preconditioning program, steers (n = 48 per treatment) received an injection (1 mL/45 kg BW) of TM (MM) or physiological saline (SAL). On d 28, all steers were weighed and divided within injection treatment (n = 24 per injection treatment) to be trucked for a 20 h transit stress period (SHIP), or returned to their pens without access to feed or water for 20 h (NS). The SHIP steers were unloaded on d 29 and all steers (SHIP and NS) 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 were assigned within treatments to receive a second injection (MM or SAL; 1 mL/68 kg BW), resulting in a 2×2×2 factorial design (n = 12 steers per treatment combination). The initial TM injection increased liver Cu, Se, and Zn concentrations (P ≤ 0.02), but did not affect ADG during preconditioning (P = 0.89), BW shrink as a result of transit (P ≥ 0.52), or plasma TM and inflammatory markers (P ≥ 0.18). Improving TM status through TM injection caused steers to have lesser ADG (P = 0.03) during the 14 d period after transit (d 29 through 43), but this was short-lived and did not affect growth during the growing period (d 5 through 112; P ≥ 0.40). Trace mineral injection had minimal effects on finishing performance and carcass characteristics. Unlike previous work, improving TM stores prior to a stressor did not improve subsequent cattle performance, likely because of the excellent TM status of the steers prior to the start of this study. As TM status of incoming feedlot cattle is generally unknown, TM injection may be a useful risk management tool to prevent lost performance due to TM deficiency. The greatest benefit of injectable TM is likely in cattle with less than adequate TM status.

Keywords: cattle, trace mineral, transit