부산대학교 도서관

Three experiments were conducted to evaluate the effects of reduced levels of phytic acid in barley on heifer growth and diet digestibility in cows. In Experiment 1, eighty-four heifers (avg wt 366 kg) were fed chopped grass-alfalfa hay and 1.13 kg/d of one of four barley varieties: 1) Harrington (3.4 g/kg phytic acid), 2) 422 (2.6 g/kg phytic acid), 3) 635 (0.96 g/kg phytic acid), and 4) 955 (0.08 g/kg phytic acid) in a 56-d growth trial. All of the barleys contained similar levels of total P (avg 5.5 g/kg). Heifers fed Harrington had the lowest (P = 0.001) ADG (0.53 kg/d). Heifers fed 422 had lower (P = 0.001) ADG (0.59 kg/d) than heifers fed 955 (0.70 kg/d), with 635-fed heifers intermediate (0.64 kg/d). In Experiment 2, eighty heifers (avg wt 282 kg) were fed chopped grass-alfalfa hay and the same barley diets as in Experiment 1 for 56 d. Heifers fed Harrington and 955 had greater (P = 0.001) ADG (avg 1.01 kg/d) than heifers fed 635 and 422 (avg 0.86 kg/d). In Experiment 3, 32 pregnant crossbred cows individually fed chopped hay (6.28% CP) ad libitum in Calan gates were assigned to one of the same four barley diets as above. Cows were individually fed hay and 1.36 kg barley at 0700 daily, hay at 1600 and feed refusals were weighed to determine forage intake. There was no effect of barley variety on hay DM, OM, CP, NDF, or ADF intake or digestibility (P > 0.60). It appears that phytic acid levels in barley may have an effect on weight gain of heifers, but the mechanism of action is unclear. Key Words: Phytic acid, Barley, Beef cattle