Roberts K I, Bennison J, McDougall S
a Cognosco, AnexaFVC , PO Box 21, Morrinsville , 3330 , New Zealand.
b Agrimin , Arlanda Way, Humberside Airport, Kirmington, North Lincolnshire , DN39 6YH , UK.
N Z Vet J. 2019 Jan;67(1):20-26. doi: 10.1080/00480169.2018.1520654. Epub 2018 Sep 26.
AIMS To assess the effect of the administration of two oral Ca boluses on concentrations of total Ca, β-hydoxybutyrate (BHB) and non-esterified fatty acids (NEFA) in serum, and urine pH, in recently calved pasture-fed dairy cows. METHODS Friesian or Friesian cross Jersey cows from one dairy farm were blocked by age and randomly assigned to no treatment (control; n=14), or treatment (n=13) with two oral Ca boluses administered approximately 12 hours apart, with the first bolus being given within 14 hours of calving. Each bolus weighed 198 g and contained 43 g of Ca; 31 g of Ca from calcium chloride and 12 g of Ca from calcium sulfate. Cows were enrolled over three calendar days, and all cows were managed in one group during the 24-hour study period. Blood samples were collected at 0, 1, 2, 4, 8, 12, 13, 14, 16, 20 and 24 hours after the initial treatment. Serum from each time point was analysed for concentrations of total Ca, and from 0, 12, and 24 hours for NEFA and BHB. Urine was collected at 0, 12 and 24 hours for pH measurement and pH was categorised as <7 or ≥7. The effect of treatment on percentage change in concentrations of Ca in serum relative to 0 hours, and concentrations of NEFA, BHB and urine pH, was examined using multivariable repeated measures mixed models with cow as a random effect. RESULTS In the final multivariable model for percentage change in concentrations of Ca, there was an interaction between time and treatment (p=0.004), with the percentage increase being higher in treatment than control cows at 1, 2, 4, 8 and 13 hours. At 12 hours, 5/13 (41%) treated cows had a urine pH <7compared to 0/12 (0%) control cows (p<0.001), and at 24 hours 13/13 (100%) treated cows had urine pH <7 compared to 0/12 (0%) control cows (p<0.001). Over the 24-hour period, mean concentrations of NEFA or BHB in serum were similar in treated and control cows (p>0.3). CONCLUSIONS AND CLINICAL RELEVANCE Oral treatment with two Ca boluses increased concentrations of total Ca in serum and decreased urine pH in pasture-fed cows. This bolus has the potential to reduce the prevalence and duration of subclinical hypocalcaemia in recently calved cows.
目的 评估给近期产犊的牧场饲养奶牛口服两次钙丸剂对血清总钙、β-羟基丁酸（BHB）和非酯化脂肪酸（NEFA）浓度以及尿液pH值的影响。方法 来自一个奶牛场的弗里西亚牛或弗里西亚杂交泽西牛按年龄进行分组，然后随机分为不进行处理（对照组；n = 14）或进行处理（n = 13），即每隔约12小时口服两次钙丸剂，第一次钙丸剂在产犊后14小时内给予。每粒钙丸重198 g，含43 g钙；其中31 g钙来自氯化钙，12 g钙来自硫酸钙。在三个日历日内纳入奶牛，在24小时的研究期间，所有奶牛集中在一个组进行管理。在初始处理后的0、1、2、4、8、12、13、14、16、20和24小时采集血样。分析每个时间点血清中的总钙浓度，以及在0、12和24小时时的NEFA和BHB浓度。在0、12和24小时收集尿液用于测量pH值，并将pH值分为<7或≥7。使用以奶牛为随机效应的多变量重复测量混合模型，研究处理对血清钙浓度相对于0小时的变化百分比以及NEFA、BHB浓度和尿液pH值的影响。结果 在最终的血清钙浓度变化百分比多变量模型中，时间和处理之间存在交互作用（p = 0.004），在1、2、4、8和13小时时，处理组奶牛的钙浓度增加百分比高于对照组奶牛。在12小时时，13头处理组奶牛中有5头（41%）尿液pH <7，而12头对照组奶牛中无1头（0%）尿液pH <7（p<0.001）；在24小时时，13头处理组奶牛中有13头（100%）尿液pH <7，而12头对照组奶牛中无1头（0%）尿液pH <7（p<0.001）。在24小时期间，处理组和对照组奶牛血清中NEFA或BHB的平均浓度相似（p>0.3）。结论及临床意义 给牧场饲养的奶牛口服两次钙丸剂可提高血清总钙浓度并降低尿液pH值。这种钙丸剂有可能降低近期产犊奶牛亚临床低钙血症的发生率和持续时间。
