The objectives of this experiment were to evaluate the effects of feeding diets with 2 dietary cation-anion difference (DCAD) levels and supplemented with either cholecalciferol (CH) or calcidiol (CA) during late gestation on lactation performance and energetic metabolism in dairy cows. The hypothesis was that combining a prepartum acidogenic diet with calcidiol supplementation would benefit peripartum Ca metabolism and, thus, improve energy metabolism and lactation performance compared with cows fed an alkalogenic diet or cholecalciferol. Holstein cows at 252 d of gestation were blocked by parity (28 nulliparous and 51 parous cows) and milk yield within parous cows, and randomly assigned to 1 of 4 treatments arranged as a 2 × 2 factorial, with 2 levels of DCAD (positive, +130, and negative, −130 mEq/kg) and 2 sources of vitamin D, CH or CA, fed at 3 mg per 11 kg of diet dry matter (DM). The resulting treatment combinations were positive DCAD with CH (PCH), positive DCAD with CA (PCA), negative DCAD with CH (NCH), or negative DCAD with CA (NCA), which were fed for the last 21 d of gestation. After calving, cows were fed the same lactation diet. Body weight and body condition were evaluated prepartum and for the first 49 d postpartum. Blood was sampled thrice weekly prepartum, and on d 0, 1, 2, 3, and every 3 d thereafter until 30 d postpartum for quantification of hormones and metabolites. Lactation performance was evaluated for the first 49 d postpartum. Feeding a diet with negative DCAD reduced DM intake in parous cows by 2.1 kg/d, but no effect was observed in nulliparous cows. The negative DCAD reduced concentrations of glucose (positive = 4.05 vs. negative = 3.95 mM), insulin (positive = 0.57 vs. negative = 0.45 ng/mL), and insulin-like growth factor-1 (positive = 110 vs. negative = 95 ng/mL) prepartum. Treatments did not affect DM intake postpartum, but CA-supplemented cows tended to produce more colostrum (PCH = 5.86, PCA = 7.68 NCH = 6.21, NCA = 7.96 ± 1.06 kg) and produced more fat-corrected milk (PCH = 37.0, PCA = 40.1 NCH = 37.5, NCA = 41.9 ± 1.8 kg) and milk components compared with CH-supplemented cows. Feeding the negative DCAD numerically increased yield of fat-corrected milk by 1.0 kg/d in both nulliparous and 1.4 kg/d in parous cows. Minor differences were observed in postpartum concentrations of hormones and metabolites linked to energy metabolism among treatments. Results from this experiment indicate that replacing CH with CA supplemented at 3 mg/d during the prepartum period improved postpartum lactation performance in dairy cows.

本实验的目的是评估饲喂两种饮食中的阳离子阳离子负离子差异（DCAD）并在妊娠后期补充胆钙化醇（CH）或骨化二醇（CA）的饮食对奶牛泌乳性能和能量代谢的影响。假设是与产碱饮食或胆钙化固醇的奶牛相比，产前产酸饮食与补钙糖醇的结合将有益于围产期Ca代谢，因此改善能量代谢和泌乳性能。荷斯坦奶牛在妊娠252天时被胎次（28胎和51胎）和胎牛的产奶量所阻止，并随机分配给4种处理方法中的1种，按2×2阶乘排列，DCAD的水平为2（阳性， +130，和负值，-130 mEq / kg）和2种维生素D，CH或CA的来源，每11公斤日粮干物质（DM）饲喂3毫克。产生的治疗组合是在妊娠的最后21天喂养的CH阳性DCAD（PCH），CA阳性DCAD（PCA），CH CH阴性DCAD（NCH）或CA CA阴性DCAD（NCA）。产犊后，给母牛喂相同的泌乳日粮。在产前和产后前49天评估体重和身体状况。在产前每周三次，在产后第0、1、2、3和之后每3天采血一次，直到产后30天，以进行激素和代谢物定量。评估产后前49 d的泌乳性能。饲喂DCAD阴性的日粮会使同胎牛的DM摄入量降低2.1千克/天，但对未产牛无影响。负DCAD降低了葡萄糖浓度（正= 4.05，负= 3.95 m 得到的治疗组合是在妊娠的最后21天喂养的CH阳性DCAD（PCH），CA阳性DCAD（PCA），CH CH阴性DCAD（NCH）或CA CA阴性DCAD（NCA）。产犊后，给母牛喂相同的泌乳日粮。在产前和产后前49天评估体重和身体状况。在产前每周三次，在产后第0、1、2、3和之后每3天采血一次，直到产后30天，以进行激素和代谢物定量。评估产后前49 d的泌乳性能。饲喂DCAD阴性的日粮会使同胎牛的DM摄入量降低2.1千克/天，但对未产牛无影响。负DCAD降低了葡萄糖浓度（正= 4.05，负= 3.95 m 得到的治疗组合是在妊娠的最后21天喂养的CH阳性DCAD（PCH），CA阳性DCAD（PCA），CH CH阴性DCAD（NCH）或CA CA阴性DCAD（NCA）。产犊后，给母牛喂相同的泌乳日粮。在产前和产后前49天评估体重和身体状况。在产前每周三次，在产后第0、1、2、3和之后每3天采血一次，直到产后30天，以进行激素和代谢物定量。评估产后前49 d的泌乳性能。饲喂DCAD阴性的日粮会使同胎牛的DM摄入量降低2.1千克/天，但对未产牛无影响。负DCAD降低了葡萄糖浓度（正= 4.05，负= 3.95 m 在妊娠的最后21 d喂养CA阳性的DCAD（PCA），CH阴性的DCAD（NCH）或CA阴性的DCAD（NCA）。产犊后，给母牛喂相同的泌乳日粮。在产前和产后前49天评估体重和身体状况。在产前每周三次，在产后第0、1、2、3和之后每3天采血一次，直到产后30天，以进行激素和代谢物定量。评估产后前49 d的泌乳性能。饲喂DCAD阴性的日粮可使同胎牛的DM摄入量降低2.1千克/天，但未产牛无影响。DCAD阴性可降低葡萄糖浓度（阳性= 4.05，阴性= 3.95 m 在妊娠的最后21 d喂养CA阳性的DCAD（PCA），CH阴性的DCAD（NCH）或CA阴性的DCAD（NCA）。产犊后，给母牛喂相同的泌乳日粮。在产前和产后前49天评估体重和身体状况。在产前每周三次，在产后第0、1、2、3和之后每3天采血一次，直到产后30天，以进行激素和代谢物定量。评估产后前49 d的泌乳性能。饲喂DCAD阴性的日粮可使同胎牛的DM摄入量降低2.1千克/天，但未产牛无影响。负DCAD降低了葡萄糖浓度（正= 4.05，负= 3.95 m 产犊后，给母牛喂相同的泌乳日粮。在产前和产后前49天评估体重和身体状况。在产前每周三次，在产后第0、1、2、3和之后每3天采血一次，直到产后30天，以进行激素和代谢物定量。评估产后前49 d的泌乳性能。饲喂DCAD阴性的日粮会使同胎牛的DM摄入量降低2.1千克/天，但对未产牛无影响。DCAD阴性可降低葡萄糖浓度（阳性= 4.05，阴性= 3.95 m 产犊后，给母牛喂相同的泌乳日粮。在产前和产后前49天评估体重和身体状况。在产前每周三次，在产后第0、1、2、3和之后每3天采血一次，直到产后30天，以进行激素和代谢物定量。评估产后前49 d的泌乳性能。饲喂DCAD阴性的日粮会使同胎牛的DM摄入量降低2.1千克/天，但对未产牛无影响。负DCAD降低了葡萄糖浓度（正= 4.05，负= 3.95 m 此后每隔3 d直到产后30 d进行激素和代谢物定量。评估产后前49 d的泌乳性能。饲喂DCAD阴性的日粮会使同胎牛的DM摄入量降低2.1千克/天，但对未产牛无影响。负DCAD降低了葡萄糖浓度（正= 4.05，负= 3.95 m 此后每隔3 d直到产后30 d进行激素和代谢物定量。评估产后前49 d的泌乳性能。饲喂DCAD阴性的日粮会使同胎牛的DM摄入量降低2.1千克/天，但对未产牛无影响。负DCAD降低了葡萄糖浓度（正= 4.05，负= 3.95 m中号），产前胰岛素（阳性= 0.57 vs阴性= 0.45 ng / mL）和胰岛素样生长因子-1（阳性= 110 vs.阴性= 95 ng / mL）。治疗对产后DM摄入量没有影响，但是补充了CA的母牛往往会产生更多的初乳（PCH = 5.86，PCA = 7.68 NCH = 6.21，NCA = 7.96±1.06 kg），并产生更多的脂肪校正乳（PCH = 37.0，PCA = 40.1 NCH = 37.5，NCA = 41.9±1.8公斤）和牛奶成分（与补充CH的母牛相比）。饲喂负DCAD可以在数字上使原产母牛的脂肪校正乳的产量增加1.0 kg / d，而在同胎母牛中则增加1.4 kg / d。在治疗之间观察到与能量代谢相关的激素和代谢产物的浓度存在微小差异。