Magnesium Sulfate; Zinc Propionate; Copper Propionate; Manganese Propionate; Potassium Chloride; Vitamin E Supplement; Cobalt Propionate; Sodium Selenite; Vitamin A Supplement; Vitamin D-3 Supplement; Vitamin B-12 Supplement; Riboflavin; d-Calcium Pantothenate; Choline Chloride; Niacin; Thiamine Mononitrate; Pyridoxine HCl; d-Biotin; Folic Acid; Dried Aspergillus oryzae Fermentation Extract; and Dried Fermentation Products of: Saccharomyces cerevisiae, Lactobacillus acidophilus, Lactobacillus casei and Enterococcus faecium. Inert Ingredients : Corn Oil; Calcium Silicate; Sodium Aluminosilicate; Polysorbate 80; and Sorbic Acid
Overall, there were no differences ( P ≥ ) between steers fed RAC and RAC+TM for any carcass characteristic variable measured. Back fat thickness was not different ( P = ) between steers fed RAC and steers fed RAC+TM. Several studies have reported feeding supplemental Zn may increase FT, although these reports were dependent on dosage level and type of Zn supplement. Greene et al. (1988) fed steers 360 mg Zn/d of supplemental Zn (control diets contained concentrations of 82 mg Zn/kg diet DM) from Zn methionine during a 114-d finishing period and reported FT was greater in steers supplemented with Zn when compared with steers not supplemented with Zn; however, steers supplemented with ZnO were intermediate and were not different from either treatment. Malcolm-Callis et al. (2000) observed steers during a 112-d finishing period supplemented with ZnSO 4 and reported FT was greater in steers supplemented with 100 mg Zn/kg DM (calculated Zn intake of 982 mg Zn·steer -1 ·d -1 ) compared with steers supplemented with 20 mg Zn/kg DM (calculated Zn intake of 201 mg Zn·steer -1 ·d -1 ) and 200 mg Zn/kg DM (calculated Zn intake of 1,910 mg Zn·steer -1 ·d -1 ). Furthermore, Malcolm-Callis et al. (2000) reported that when steers were supplemented with 30 mg Zn/kg DM from 3 different Zn sources (calculated Zn intake ranged from 638 to 843 mg Zn·stee r-1 ·d -1 ), FT was greater in steers supplemented with Zn amino acid complexes and Zn polysaccharide complexes when compared with steers supplemented with ZnSO 4 . In contrast, Spears and Kegley (2002) reported that steers supplemented with 25 mg Zn (ZnO or Zn proteinate)/kg DM (basal growing and finishing diets contained of 33 and 26 mg of Zn/kg of diet DM, respectively, from 3 different Zn sources, ZnO, Zn proteinate A, and Zn proteinate B) had increased FT compared to steers without Zn supplementation, but FT was not different among Zn sources. As mentioned previously, calculated Zn intake during the growing phase of that trial ( Spears and Kegley, 2002 ) was 217 mg Zn·steer -1 ·d -1 for steers not supplemented Zn and 390 to 404 mg Zn·steer -1 ·d -1 for steers supplemented Zn, and calculated Zn intake during the finishing phase was 232 mg Zn·steer -1 ·d -1 for steers not supplemented Zn and 445 to 470 mg Zn·steer -1 ·d -1 for steers supplemented Zn. Overall, many studies have shown Zn supplementation increased FT; however, this was not apparent in the present study.