Degree Type


Date of Award


Degree Name

Master of Science


Animal Science


Animal Nutrition


Our previous work has shown that feeding 5 million international units (IU) of vitamin D3 to beef steers can produce strip loin and top round steaks with greater tenderness. Our current experiment was designed to determine whether feeding two metabolites of vitamin D3, 25-hydroxyvitamin D3, and 1,25-dihydroxyvitamin D3, improves tenderness of strip loin, top round, and top blade steaks more effectively than does supplemental vitamin D3 without leaving a substantial amount of residual vitamin D3 and its metabolites in muscle. Thirty-three continental crossbred steers were allotted randomly to one of four treatment groups. The first group was fed a placebo, the second group received 5 million IU of vitamin D3, the third group received one dose of 125 mg of 25-hydroxyvitamin D3, and the fourth group received one dose of 500 [Mu]g of 1,25-dihydroxyvitamin D3. Blood samples were collected before treatment and at time of slaughter. Steaks from three different muscles were collected from each animal and aged for 8, 14, and 21 days. All steaks were assayed for tenderness by Warner-Bratzler shear force determination and by Western blot analysis. Concentrations of vitamin D3 in plasma were higher in vitamin D3-treated cattle (p<0.0001). Concentrations of plasma 25-hydroxyvitaniin D3 were increased in 25-hydroxyvitamin D3-treated cattle but were not as high as those in vitamin D3-treated cattle (p<0.0001). 1,25- Dihydroxyvitamin D3 concentrations were higher in 1,25-dihydroxyvitamin D3-treated animals when compared with all treatments (p<0.0001). Supplementing steers with vitamin D3 increased the concentration of vitamin D3 and 25-hydroxyvitamin D3 in the meat of all muscles sampled (p<0.0001). Supplementing steers with 25-hydroxyvitamin D3 increased the concentration of 25-hydroxyvitamin D3 in meat, but to an amount less than half that of cattle treated with vitamin D3. Warner-Bratzler shear force analysis showed that feeding 1,25-dihydroxyvitamin D3 did not significantly lower shear force values, but supplemental vitamin D3 and 25-hydroxyvitamin D3 produced steaks with lower shear force values (p<0.06). Analysis of Western blots showed that longissimus lumborum and semimembranous steaks from cattle fed supplemental vitamin D3 and 25-hydroxyvitamin D3 (but not steaks from cattle fed 1,25-dihydroxyvitamin D3), had greater proteolysis of troponin T to a 30-kDa component.


Copyright Owner

Monica Ruth Foote



OCLC Number


File Format


File Size

77 pages