Waterman D F, Swenson T S, Tucker W B, Hemken R W
Department of Animal Sciences, University of Kentucky, Lexington 40546.
J Dairy Sci. 1991 Jun;74(6):1866-73. doi: 10.3168/jds.S0022-0302(91)78352-5.
Eight midlactation Holstein cows (four primiparous) were assigned to replicated 4 x 4 Latin squares with a 2 x 2 factorial arrangement of treatments. The basal diet was formulated to contain 0 milliequivalents (Na + K) - Cl/100 g of diet DM. Treatment diets of high and low dietary cation-anion balance were achieved by adding appropriate amounts of supplemental Na + K (added on an equivalent basis) or Mg to the basal diet. Milk and protein yield were increased as well as DMI and FCM for Na + K diets The high concentration of cation increased milk fat percentage. The cation-anion balance (using Mg as a cation) had no effect on any of the production parameters observed. The higher cation-anion balances increased blood bicarbonate levels and plasma Na. Urinary Ca excretion was increased for the Mg diets. Urinary pH increased with both the source of cation (Na + K) and the concentration of cation (high) in the diet. other minerals were unaffected in milk, plasma, or urine. Responses measured in this trial reflect treatments calculated using the equation milliequivalents (Na + K) - Cl/100 g diet DM or (Na + K) - (Cl + S)/100 g diet DM, suggesting that Mg plays a minor role in dietary cation-anion balance.
八头处于泌乳中期的荷斯坦奶牛（四头初产牛）被分配到重复的4×4拉丁方设计中，采用2×2析因处理安排。基础日粮被配制为每100克日粮干物质含0毫当量（钠+钾）-氯。通过向基础日粮中添加适量的补充钠+钾（以等量添加）或镁来实现高和低日粮阴阳离子平衡的处理日粮。钠+钾日粮使牛奶和蛋白质产量增加，干物质采食量和校正乳产量也增加。阳离子浓度升高使乳脂率提高。阴阳离子平衡（以镁作为阳离子）对所观察的任何生产参数均无影响。较高的阴阳离子平衡使血液碳酸氢盐水平和血浆钠升高。镁日粮使尿钙排泄增加。日粮中阳离子来源（钠+钾）和阳离子浓度（高）均使尿液pH升高。其他矿物质在牛奶、血浆或尿液中未受影响。本试验中测得的反应反映了使用毫当量（钠+钾）-氯/100克日粮干物质或（钠+钾）-（氯+硫）/100克日粮干物质公式计算的处理结果，表明镁在日粮阴阳离子平衡中作用较小。
