阴离子型日粮及补Ca对围产期奶牛代谢与健康及其生产性能的影响

将36头干奶后期中国荷斯坦奶牛随机分为对照组、试验Ⅰ组、试验Ⅱ组（每组12头）．分别饲喂常规日粮、阴离子型日粮及在此基础上朴Ca日粮，探讨其对奶牛体内代谢状况、健康状况及生产性能的影响。与饲喂常规日粮相比，饲喂阴离子型日粮可降低奶牛尿液pH值（P〈0．01）和血液HCO2^-浓度（P〉0．05）；增加奶牛产后12h（P〈0．05）、2d（P〈0．05）血清总钙含量．对血清无机磷、镁含量没有显著影响；明显降低奶牛亚临床性低血钙率（33％）、胎衣不下率（33％）和乳房水肿率（17％）；增加牛奶乳糖率（P〈0．05），对其他奶成分和奶产量没有显著影响（P〉0．05）。在阴离子型日粮中补Ca后．与饲喂阴离子型日粮相比．除增加奶牛产后血清镁含量外（P〈0．05）．对其他各项指标没有明显影响。

Effects of Low Dietary Cation-anion Balance Diet and Calcium Supplementation on Metabolism ,Health Status and Performance in Transition Dairy Cows

Thirty-six Chinese Holstein dry dairy cows at around 20 d prepartum were randomly distributed into three groups,and fed one of the following diets:conventional diet(control),low dietary cation-anion balance diet(DCAB,added with anionic salt,Treatment 1),and low DCAB diet plus calcium(Treatment 2).The effects were investigated on body metabolism,health status and lactation performance.Compared with the control,feeding of low DCAB diet decreased urine pH(P<0.01),blood pH(P<0.01),and blood HCO-_3 concentration(P>0.05);and increased serum total calcium concentration at 12 h and 2 d(P<0.05) postpartum,but had no significant effects on serum inorganic phosphorus and magnesium concentration(P>0.05).Incidence of subclinical hypocalcemia,retained placenta and udder oedema were 33,33 and 17% lower in cows consuming low DCAB diet than those on control diet.Low DCAB diet had 0.15%(P<0.05) higher milk lactose content than control diet,though there were statistically significant impacts on milk yield and other milk compositions(P>0.05) between three different diet treatments.When the low DCAB diet was added with calcium,no further improvements in the above-mentioned parameters were observed,except for the higher serum magnesium concentration postpartum(P<0.05).