Effects of supplemental vitamin D-3 on feed intake, carcass characteristics, tenderness, and muscle properties of beef steers

Research was conducted to determine the effects of supplemental dietary vit amin D-3 on DMI, carcass traits, Warner Bratzler shear (WBS) force, calpast atin activity, plasma minerals, pH (0, 3, 12, and 24 h after slaughter), wa ter-holding capacity (WHC), and sensory characteristics of three muscles. P re-slaughter vitamin D-3 treatments included no supplemental vitamin D-3, 6 x 10(6) IU (MIU) of vitamin D-3 for 4 d, or 6 MIU of vitamin D-3 for 6 d. Cattle were slaughtered and carcasses were chilled for 48 h before removal of steaks from the longissimus, gluteus medius, and biceps femoris muscles. Steaks were aged at 2 degreesC for 7, 14, or 21 d before cooking to a fina l internal temperature of 70 degreesC for WBS and sensory panel analysis. D ry matter intake was lower for steers supplemented with vitamin D-3 for 4 o r 6 d. Live and carcass weights were lower (P < 0.05) in steers supplemente d with vitamin D-3- Supplementing 6 MIU/6 d of vitamin D-3 decreased (P < 0 .05) WBS values of gluteus steaks (pooled over aging times). Longissimus st eaks from steers supplemented with vitamin D-3 for 6 d had lower (P < 0.05) WBS force values than these steaks from control steers or steers fed vitam in D-3 for 4 d at 7 d postmortem. Biceps femoris steaks from steers receivi ng vitamin D-3 for 4 d had higher WBS values than steaks from control steer s at 14 and 21 d postmortem. Feeding vitamin D: at 6 MIU for 6 d decreased (P < 0.05) the percentage of steaks that had WBS values greater than or equ al to 3.86 kg for all steaks. Feeding vitamin D-3 had no effect on palatabi lity traits evaluated by trained panelists. Blood Ca concentrations were gr eater (P < 0.05) when vitamin D3 was fed and with increased vitamin D3 feed ing time. Feeding vitamin D3 for 6 d (vs 4 d) delayed pH decline for all mu scle types after 0, 3, and 12 h postmortem. Water-holding capacity was incr eased (P > 0.02) after 0 h, 24 h, and 21 d postmortem when vitamin D-3 was fed and was greater at 0 and 24 h if vitamin D-3 was fed for 6 d rather tha n 4 d. These data suggest that supplementing 6 MIU of vitamin D-3 Will decr ease DMI and improve beef tenderness through increased blood plasma Ca conc entrations and WHC.