328 Effects of Supplemental Zinc Concentration and Source on Performance and Biomarkers of Immune Status in Receiving Steers

Abstract Weaned Angus-crossbred steers (n = 72; 626 ± 54 lbs) were enrolled in a 42-d receiving study evaluating trace mineral (TM) source and concentration on growth performance, immune, TM status. Steers housed pens of 6, equipped with GrowSafe bunks to determine individual feed disappearance. Dietary treatments 24 steers/treatment) included: 1) from an organic (Availa4; Zinpro Corp., Eden Prairie, MN) at 7 g∙steer-1∙d-1; for 42 d (ORG); 2) ORG entire plus AvailaZn provide 1,000 mg Zn∙steer-1∙d-1 first 14 (ORG+Z); 3) inorganic sources match (ING) 42-d. Cattle weighed -1, 0, 14, 41, 42. Data analyzed using Proc Mixed fixed effect treatment steer as experimental unit. Initial BW was covariate performance. Final overall ADG did not differ (P ≥ 0.19). However, DMI tended 0.06) G:F greater 0.04) ORG+Z than ING, intermediate. Plasma Zn increased 0 while (Day; P 0.02) unaffected by (p value). Based repeated measures, plasma Cu ING ORG+Z, intermediate concentrations decreased over time 0.01). Frequency total circulating NK CD8 T cells measured 0.07). Markers activation (CD16, CD44 CD8) differed ≤ 0.05). In this study, supplementation improved efficiency received weaned beef influenced markers immune function.