Chan P S, West J W, Bernard J K
Department of Animal and Dairy Science, University of Georgia Coastal Plain Experiment Station, Tifton 31793-0748, USA.
J Dairy Sci. 2006 Feb;89(2):704-13. doi: 10.3168/jds.S0022-0302(06)72133-6.
Nine multiparous and 12 primiparous cows were fed diets containing an anionic salt supplement and moderate Ca (0.99%) or high Ca (1.50%) concentrations for 21 d prepartum to determine the effects of dietary Ca concentration on serum and urine electrolytes and on postpartum intake and milk yield. Blood samples were collected during 21 to 1 d prepartum, 0 to 2 d postpartum, and 3 to 21 d postpartum. Dietary cation-anion difference (DCAD) for prepartum diets was approximately -6 mEq/100 g of dry matter (Na + K - Cl - S). Immediately postpartum, cows were fed diets with positive DCAD with greater than 1.00% Ca concentration. Mean serum Ca concentrations 21 to 1 d prepartum, 0 to 2 d postpartum, and 3 to 21 d postpartum were 9.62, 8.41, and 9.38 mg/dL. There were no treatment effects on serum Ca concentration. Mean serum Ca concentration was higher for primiparous than multiparous cows (9.34 vs. 8.93 mg/dL) for the trial and at calving (8.77 vs. 8.13 mg/dL). Mean serum HCO(3)(-) and urinary pH, respectively, were 20.32 mEq/L and 5.67 prepartum, 25.82 mEq/L and 7.62 at calving, and 26.08 mEq/L and 8.25 postpartum. No differences due to treatment were observed for serum and urinary concentrations of HCO(3)(-), pH, Mg, Na, K, and Cl. Milk yield was similar for 0.99 and 1.50% Ca treatments (22.8 and 20.7 kg/d). Diets containing 0.99 or 1.5% Ca maintained serum Ca at adequate levels around parturition and resulted in similar dry matter intake and postpartum milk yield.
9头经产奶牛和12头初产奶牛在产前21天被饲喂含有阴离子盐补充剂且钙浓度适中（0.99%）或较高（1.50%）的日粮，以确定日粮钙浓度对血清和尿液电解质以及产后采食量和产奶量的影响。在产前21天至1天、产后0至2天以及产后3至21天采集血样。产前日粮的日粮阴阳离子差（DCAD）约为-6 mEq/100 g干物质（钠+钾-氯-硫）。产后立即给奶牛饲喂DCAD为正且钙浓度大于1.00%的日粮。产前21天至1天、产后0至2天以及产后3至21天的血清钙平均浓度分别为9.62、8.41和9.38 mg/dL。日粮处理对血清钙浓度没有影响。在整个试验期间以及产犊时，初产奶牛的血清钙平均浓度高于经产奶牛（分别为9.34和8.93 mg/dL以及8.77和8.13 mg/dL）。产前血清碳酸氢根（HCO₃⁻）平均浓度和尿液pH分别为20.32 mEq/L和5.67，产犊时分别为25.82 mEq/L和7.62，产后分别为26.08 mEq/L和8.25。未观察到日粮处理对血清和尿液中HCO₃⁻浓度、pH、镁、钠、钾和氯的影响。钙浓度为0.99%和1.50%的处理产奶量相似（分别为22.8和20.7 kg/天）。含有0.99%或1.5%钙的日粮在分娩前后将血清钙维持在适当水平，并导致相似的干物质采食量和产后产奶量。
