The use of vitamin D-3 to improve beef tenderness

An experiment was designed to test the hypothesis that short-term oral admi nistration of dietary vitamin D-3 to beef cattle before slaughter would inc rease beef tenderness through greater calcium-activated calpain activity in postmortem aged skeletal muscle. Thirty continental crossbred steers were allotted randomly to three treatment groups housed in one pen. One group se rved as a control; two other groups were administered boluses with either 5 x 10(6) or 7.5 x 10(6) IU of vitamin D-3 daily for 9 d. Cattle were slaugh tered 1 d later. The longissimus lumborum was excised from each carcass 72 h postmortem and steaks removed at 3, 7, 14, and 21 d postmortem. The semim embranosus muscle (top round) was excised from each carcass 72 h postmortem and steaks removed at 7, 14, and 21 d postmortem. Blood plasma calcium con centration of cattle treated with 5 or 7.5 x 10(6) IU of vitamin D-3 was hi gher (P < .05) than that of controls. Strip loin and top loin steaks from c attle fed supplemental doses of vitamin. D-3 had lower (P < .05) Warner-Bra ttier (W-B) shear values at 14 d postmortem but were not significantly diff erent from controls at 3, 7, or 21 d (strip loins) or 7; or 21 d (top round s). No significant difference in strip loin steak tenderness was observed b y sensory panel at 14 d postmortem (P < .17) between steaks from control an d vitamin D-3-treated steers. At 14 d postmortem, strip loin and top round steaks from cattle fed 5 x 10(6) IU of vitamin D-3, but not from those give n 7.5 x 10(6) IU, showed more proteolysis (P < .05) than did steaks from co ntrol cattle, based on Western blotting analysis. Therefore, the use of sup plemental dietary vitamin D-3 given daily for 9 d before slaughter did impr ove tenderness (lower W-B shear values) of 14-d postmortem aged beef. Incre ased proteolysis seems to be the mechanism of tenderization.