Submitted to: American Society of Animal Science Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 9/30/1998
Publication Date: N/A
Citation: N/A Interpretive Summary:
Technical Abstract: Feedlot steers (n=167) of Bos indicus and Bos taurus breeding were fed 1 of 6 vit D3 treatments 8 consecutive d starting 10 d prior to slaughter. A total of 42 pens of 4 steers each were blocked into 7 categories according to average weight. The 6 vit D3 treatments consisted of either no supplemental vit d3, 1/2 million, 1 million, 2.5 million, 5 million, or 7.5 million IU/steer/d. Plasma Ca was measured during the 8 d supplementation period. After slaughter, tissue samples from the strip loin and liver were taken. Residues of vit D3 and 2 of its metabolites, 25-OHD3 and 1,25-OH2D3, were determined for liver and lean tissues via HPLC and radioactive enzyme techniques. Vit D3 feeding increased plasma Ca (P less than .05). At slaughter, plasma Ca concentrations were 8.7, 9.2, 9.4, 9.9, 10.1, and 10.4 mg Ca++/dl for 0, 1/2, 1, 2.5, 5, and 7.5 million treatments, respectively. Vit D3 treatments of 1 million IU/steer/d or greater increased vit D3 concentrations in strip loin and liver samples (P less than .05). Feeding 5 million IU/steer/d for 8 d resulted in the highest increase in vit D3 concentrations, which were 4x higher in the liver and a 7x increase in the strip loin vs. control (P less than .05). Cooking liver to 75 C resulted in a 10-30% reduction in vit D3 concentrations. Feeding 5 and 7.5 million IU/steer/d of vit D3 increased the metabolite 25-OHD3 concentrations in both liver and strip loin samples. The 6 treatments did not differ in 1,25-OH2D3 metabolite concentrations in liver and strip loin samples. Thus, vit D3 treatments of 1 million IU/steer/d or greater for 8 consecutive d will increase conc of vit D3 and treatments of 5 and 7.5 million IU/steer/d of vit D3 will increase the vit D metabolite 25-OHD3 conc in muscle and liver.