Department of Animal Science, Cornell University, Ithaca, NY 14853.
Papillon Agricultural Company Inc., Easton, MD 21601.
J Dairy Sci. 2017 Sep;100(9):7183-7197. doi: 10.3168/jds.2017-12773. Epub 2017 Jul 12.
The objective of this study was to determine the effects of feeding different supplemental sources of Ca and Mg in the peripartum period, and different dietary levels of Mg postpartum, on plasma mineral status, performance, and aspects of energy metabolism in transition dairy cows. Multiparous Holstein cows (n = 41) were used in a completely randomized design with a 2 × 2 factorial arrangement of treatments starting at 28 d before expected parturition. Main effects were source assignments (CS = common sources of supplemental Ca and Mg, or MA = a blend of common and commercial mineral sources with supplemental minerals primarily from a commercial Ca-Mg dolomite source; MIN-AD, Papillon Agricultural Company Inc., Easton, MD) beginning at 21 d before due date; cows were further randomized within source treatments to 1 of 2 levels of Mg supplementation (LM = formulated postpartum diet Mg at 0.30% of dry matter (DM), or HM = formulated postpartum diet Mg at 0.45% of DM) beginning within 1 d after parturition. Final treatment groups included the following: common source, low Mg (CS-LM, n = 11); common source, high Mg (CS-HM, n = 11); MIN-AD, low Mg (MA-LM, n = 10); and MIN-AD, high Mg (MA-HM, n = 9). Treatment diets were fed and data collected through 42 d in milk. Postpartum plasma Mg concentrations tended to be higher for cows fed HM and cows fed CS, but no effects were observed on peripartum plasma Ca concentrations. Peripartum plasma P concentrations were higher for cows fed MA. Dry matter intake (DMI) in the prepartum period was higher for cows fed MA (CS = 15.9 vs. MA = 16.8 kg/d) and postpartum DMI was higher in some groups depending on week. Plasma nonesterified fatty acid concentrations were lower for cows fed MA during both the prepartum and postpartum periods. A source by level interaction was observed for postpartum plasma β-hydroxybutyrate (BHB) concentrations such that cows fed CS-LM had numerically higher BHB and cows fed MA-LM had numerically lower BHB (geometric means; CS-LM = 7.9, CS-HM = 6.9, MA-LM = 6.3, and MA-HM = 7.3 mg/dL) than cows fed the other 2 treatments. Higher milk fat yield, milk fat content, and fat- and energy-corrected yield during wk 1 for cows fed MA resulted in source by week interactions for these outcomes. This study demonstrated that varying supplemental Ca and Mg sources and feeding rates had minimal effect on plasma Ca status despite differences in plasma Mg and P concentrations. Effects on DMI and plasma energy metabolites suggest an opportunity for strategic use of mineral sources in the transition period to promote metabolic health.
本研究旨在确定围产期不同补充钙和镁来源以及产后不同镁水平对围产后期奶牛血浆矿物质状况、生产性能和能量代谢方面的影响。采用完全随机设计，将 41 头经产荷斯坦奶牛分为 2×2 因子处理，从预计分娩前 28 天开始。主要处理为来源分配（CS=共同补充钙和镁来源，或 MA=共同和商业矿物质来源的混合物，补充矿物质主要来自商业钙镁白云石源；Papillon Agricultural Company Inc.，Easton，MD），从预产期前 21 天开始；在产后 1 天内，奶牛在源处理内进一步随机分为 2 个镁补充水平之一（LM=产后日粮中镁的配方为 0.30%干物质（DM），或 HM=产后日粮中镁的配方为 0.45% DM）。最终处理组包括以下几种：共同来源，低镁（CS-LM，n=11）；共同来源，高镁（CS-HM，n=11）；MIN-AD，低镁（MA-LM，n=10）；MIN-AD，高镁（MA-HM，n=9）。在 42 天的泌乳期内，奶牛一直饲喂处理日粮并收集数据。产后血浆镁浓度在饲喂 HM 和 CS 的奶牛中趋于较高，但围产期血浆钙浓度没有影响。产后血浆磷浓度在饲喂 MA 的奶牛中较高。产前干物质采食量（DMI）在饲喂 MA 的奶牛中较高（CS=15.9 比 MA=16.8 kg/d），产后 DMI 在某些组中因周而异较高。围产后期，饲喂 MA 的奶牛血浆非酯化脂肪酸浓度较低。产后血浆β-羟丁酸（BHB）浓度存在来源与水平的互作，这表明饲喂 CS-LM 的奶牛 BHB 浓度较高，而饲喂 MA-LM 的奶牛 BHB 浓度较低（几何平均值；CS-LM=7.9、CS-HM=6.9、MA-LM=6.3、MA-HM=7.3mg/dL），高于其他 2 种处理的奶牛。饲喂 MA 的奶牛在第 1 周的产奶量、乳脂率、脂肪和能量校正产量较高，这导致这些结果存在来源与周的互作。本研究表明，尽管血浆镁和磷浓度存在差异，但改变补充钙和镁的来源和喂养率对血浆钙状况几乎没有影响。对 DMI 和血浆能量代谢物的影响表明，在围产期有机会战略性地使用矿物质来源，以促进代谢健康。
