Pregnancy and lactation in beef heifers grazing tallgrass prairie in the winter: influence on intake, forage utilization, and grazing behavior.

摘要: Six ruminally and eight bifistulated (ruminal esophageal) Hereford x Angus heifers were used to determine effects of pregnancy early lactation on forage intake utilization under grazing conditions. Three three bred (pregnant/lactating; P/L; average calving date was February 11, 1989); remaining served as controls (C). The experiment consisted periods (P1 = 55 d before parturition; P2 12 P3 26 after parturition). All grazed the same 24-ha Flint Hills range pasture. Dehydrated alfalfa pellets supplemented at .5% BW/heifer daily prepartum .8% postpartum. Treatment period interactions noted (P less than .10) for OM intake, ruminal capacity, indigestible ADF (IADF) fill, time but not digestibility or IADF passage rate greater .10). In P1 P3, P/L had C heifers, whereas no differences in P2. Pregnant/lactating spent did more P3. Ruminal fill measured by water tended .14 .16, respectively) differ between two groups Digestibility unaffected physiological status, heifers. Only minor chemical composition diets selected groups. fermentation patterns shifted only slightly; largest when propionate acetate (mol/100 mol) summary, during just parturition, disappeared, capacity be lower Intake 16% postpartum period. Organic matter influenced even though rates