Rahnema S, Wu Z, Ohajuruka O A, Weiss W P, Palmquist D L
Department of Dairy Science, Ohio State University, Wooster 44691.
J Anim Sci. 1994 Jan;72(1):229-35. doi: 10.2527/1994.721229x.
Five lactating Holstein cows with ruminal and duodenal cannulas were used in a 5 x 5 Latin square to determine the site of mineral absorption and effects of sources and amount of dietary fat on apparent absorption. Cows were fed (DM, 17.4 +/- .8 kg/d) chopped alfalfa hay, alfalfa haylage, corn silage, and concentrate at 1:1:1:2 (DM) at 12-h intervals. Calcium salts of palm fatty acid distillate (CS) or animal-vegetable (AV) fat were 0% (control), 2.5% (low, L), or 5.0% (high, H) of the diet DM. After 2 wk of adaptation, duodenal and fecal grab samples were collected at 7-h intervals for 5 d and composited by animal. Calcium intake increased (P < .05) with high-fat diets (195 vs 170 g/d), whereas Mg intake remained unchanged (54.3 +/- 9.0 g/d). Apparent absorption, estimated by Cr2O3, was regressed on Ca or Mg intake (grams/day) and fatty acid (FA) intake (grams/day). Total absorption of Ca (grams/day) = -37.4 + .264 Ca (P = .07, R2 = .14). Ruminal absorption of Mg was independent of FA intake, and magnesium was secreted posterior to the duodenum. Total tract Mg absorption (grams/day) was described by -7.685 + .464 Mg -.0044 FA (P < .0005, R2 = .46). Fat intake decreased (P < .05) total tract Mg absorption, and Ca absorption was decreased by high fat compared with low fat intake (P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)
选用5头安装了瘤胃和十二指肠瘘管的泌乳荷斯坦奶牛，采用5×5拉丁方设计，以确定矿物质吸收部位以及日粮脂肪来源和含量对表观吸收的影响。每隔12小时给奶牛饲喂（干物质，17.4±0.8千克/天）切碎的苜蓿干草、苜蓿青贮、玉米青贮和精料，比例为1:1:1:2（干物质）。棕榈脂肪酸蒸馏物钙盐（CS）或动植物脂肪（AV）占日粮干物质的比例分别为0%（对照）、2.5%（低，L）或5.0%（高，H）。适应2周后，每隔7小时采集一次十二指肠和粪便抓取样本，持续5天，并按动物进行混合。高脂肪日粮组的钙摄入量增加（P<0.05）（195对170克/天），而镁摄入量保持不变（54.3±9.0克/天）。通过三氧化二铬估算的表观吸收量与钙或镁摄入量（克/天）以及脂肪酸（FA）摄入量（克/天）进行回归分析。钙的总吸收量（克/天）=-37.4+0.264钙（P=0.07，R2=0.14）。瘤胃对镁的吸收与脂肪酸摄入量无关，镁在十二指肠后方分泌。全肠道镁吸收量（克/天）可用-7.685+0.464镁-0.0044脂肪酸来描述（P<0.0005，R2=0.46）。脂肪摄入量降低了全肠道镁吸收量（P<0.05），与低脂肪摄入量相比，高脂肪摄入量降低了钙吸收量（P<0.05）。（摘要截选至250字）
