Grace N D, Pearce S G, Firth E C, Fennessy P F
AgResearch Grasslands, Palmerston North, New Zealand.
Aust Vet J. 1999 Mar;77(3):177-80. doi: 10.1111/j.1751-0813.1999.tb11230.x.
To determine the changes in Ca, P, Mg, Na, K, S, Cu, Fe and Zn concentrations of milk during the lactation in pasture-fed Thoroughbred mares and then calculate the dietary mineral requirements of the sucking foal and the lactating mare.
Milk was sampled on days 1, 3, 7, 14, 21, 28 and at various times between 55 to 65, 85 to 95 and 135 to 150 days after parturition from 21 pasture-fed mares. The concentrations of macro- and micro-elements in the milk were determined by inductively coupled plasma emission spectrometry.
Concentrations (mg/L) of these elements were highest in colostrum (Mg 302, Na 561, K 955, S 1035, Cu 0.76, Fe 0.79 and Zn 5.5) except for Ca (1245) and P (895), which where highest on day 7. The mean milk mineral element concentrations (mg/L) over days 55 to 150 were Ca 843, P 543, Mg 47, Na 120, K 590, S 219, Cu 0.19, Fe 0.34 and Zn 2.1. The mean plasma element concentrations (mg/L) over the same period were Ca 120, P 77.1, Mg 17.0, Na 3110, K 168, S 983, Cu 1.1, Fe 1.5 and Zn 0.49. Concentration gradients between plasma and milk were observed and, in the case of Ca, P, Mg, K and Zn, their concentrations in milk were greater than those in plasma, while a reverse situation was observed for Na, S, Cu and Fe.
With the exception of Ca and P, the highest concentrations of mineral elements were observed in the colostrum. The nursing foal should have access to good pasture or creep feed, because the intakes of Ca, P and Cu from milk may be less than optimum to meet the daily mineral element requirements.
测定在牧场饲养的纯种母马泌乳期内牛奶中钙、磷、镁、钠、钾、硫、铜、铁和锌的浓度变化，然后计算吮乳幼驹和泌乳母马的日粮矿物质需求量。
从21匹牧场饲养的母马中，在产后第1、3、7、14、21、28天以及产后55至65天、85至95天和135至150天的不同时间采集牛奶样本。通过电感耦合等离子体发射光谱法测定牛奶中常量和微量元素的浓度。
除钙（1245）和磷（895）在第7天最高外，这些元素的浓度（mg/L）在初乳中最高（镁302、钠561、钾955、硫1035、铜0.76、铁0.79和锌5.5）。在55至150天期间，牛奶矿物质元素的平均浓度（mg/L）为钙843、磷543、镁47、钠120、钾590、硫219、铜0.19、铁0.34和锌2.1。同期血浆元素的平均浓度（mg/L）为钙120、磷77.1、镁17.0、钠3110、钾168、硫983、铜1.1、铁1.5和锌0.49。观察到血浆和牛奶之间的浓度梯度，就钙、磷、镁、钾和锌而言，它们在牛奶中的浓度高于血浆中的浓度，而钠、硫、铜和铁则观察到相反的情况。
除钙和磷外，矿物质元素的最高浓度出现在初乳中。哺乳幼驹应能吃到优质牧场的草或补饲，因为从牛奶中摄入的钙、磷和铜可能不足以满足每日矿物质元素需求。
