Delaquis A M, Block E
Department of Animal Science, McGill University, Ste. Anne de Bellevue, QC, Canada.
J Dairy Sci. 1995 Sep;78(9):2024-39. doi: 10.3168/jds.S0022-0302(95)76828-X.
Ten Holstein and 2 Ayrshire cows were used in a switchback design to compare diets based on alfalfa haylage and corn silage. Both diets had a similar cation-anion difference and contained 1% NaHCO3. Dietary treatment did not affect DMI, DM digestibility, milk production, or milk composition. Intake, absorption, and urinary excretion of N were significantly increased by the ration based on haylage, but the overall balance remained unaffected. Cows consuming haylage absorbed and excreted significantly more water than did cows consuming corn silage and consequently had significantly larger urine volumes. Blood volume was increased by the ration based on haylage. Intakes of Mg, K, Cl, and S differed between diets, but only K balance was increased by the diet based on haylage. The fractional excretion of K, Cl, and S in urine was increased by the diet based on haylage, demonstrating that the kidneys responded to the increased intakes by diminishing the reabsorption or by increasing the secretion of these minerals. Acid-base parameters for blood, urine, and milk were unaffected by dietary treatment. A diet based on alfalfa haylage, compared with a diet based on corn silage with similar cation-anion difference, resulted in different water and mineral metabolism but did not affect the acid-base status of cows in early lactation.
选用10头荷斯坦奶牛和2头爱尔夏奶牛，采用折返式设计比较以苜蓿青贮和玉米青贮为基础的日粮。两种日粮的阴阳离子差相似，均含有1%的碳酸氢钠。日粮处理对干物质采食量、干物质消化率、产奶量或乳成分没有影响。以青贮干草为基础的日粮显著增加了氮的摄入量、吸收量和尿排泄量，但总体平衡未受影响。采食青贮干草的奶牛比采食玉米青贮的奶牛吸收和排泄的水分显著更多，因此尿量也显著更大。以青贮干草为基础的日粮增加了血容量。两种日粮的镁、钾、氯和硫摄入量不同，但只有以青贮干草为基础的日粮增加了钾平衡。以青贮干草为基础的日粮增加了尿中钾、氯和硫的排泄分数，表明肾脏通过减少这些矿物质的重吸收或增加其分泌来应对摄入量的增加。日粮处理对血液、尿液和乳汁的酸碱参数没有影响。与具有相似阴阳离子差的玉米青贮日粮相比，以苜蓿青贮为基础的日粮导致了不同的水和矿物质代谢，但不影响早期泌乳奶牛的酸碱状态。
