Effects of Concentration and Source of Trace Minerals on Performance, Immunity, Mineral and Lipid Metabolism, and Carcass Characteristics of Beef Steers

Two hundred seventy-nine steers were blocked by initial BW, stratified by estimated breed, and randomly assigned to pens and treatments within weight replication. Mineral treatments administered during the receiving phase consisted of Cu, Zn, Mn, and Co administered at the following levels: 1) two times the NRC (1996) recommendation from amino acid complex Availa-4® (Zinpro, Eden Prairie, MN); 2) at the NRC recommendation from Availa-4®, 3) three times the NRC recommendation from inorganic minerals, or 4) six times the NRC recommendation from inorganic minerals. Steers were gradually switched from a moderate to high concentrate corn-alfalfa diet. Finishing phase mineral treatments consisted of 1) mineral treatment from Availa-4® fed at NRC recommendations, 2) mineral treatment from Availa-4® fed at one and one-half times the NRC recommendation, 3) minerals from inorganic sulfate sources fed at one and one-half times the NRC recommendation, or 4) minerals from inorganic sulfate sources fed at three times the NRC recommendation. Eight pens from each treatment were harvested after being fed for a period of 198 or 230 d. Average daily feed intake was reduced (P<0.0001) in steers receiving the inorganic mineral supplementation at six times the NRC recommendation from d 0 to 28. Overall feed efficiency was improved (P<0.01) with the inorganic supplementation at three times the NRC recommendation compared with the organic treatment at the NRC-recommended level. Hepatic Cu stores increased (P<0.0001) with elevated concentrations of Cu in the diet. Overall antibody titer response to bovine rhinotracheitis (IBR) was not different (P>0.05) between treatments. Steers on the organic mineral treatment at one and one-half times the NRC recommendation had greater (P<0.05) C18:1 cis and C18:2 cis-9 trans-11 fatty acids in the longissimus than did steers receiving the inorganic mineral supplement at one and one-half times the NRC recommendation. These results indicate that trace mineral concentration and source had minimal effects on performance and immunity. However, it appears that mineral source may alter lipid metabolism in steers.