经产荷斯坦奶牛产前尿液pH值与围产期血钙浓度之间的关联
Associations between prepartum urine pH and periparturient blood calcium concentrations in multiparous Holstein cows.
作者信息
Goff Jesse P, Melendez Pedro, Bartolome Julian A, Overton Thomas R, Leno Brittany M, Graef Geneva, Drackley James K, Glosson Kristen M, Zhang Xiangfei, LeBlanc Stephen J, Couto-Serrenho Rita, Santos José E P, Lopera Camilo, Zimpel Roney, Rodney Rachael M, Lean Ian J
机构信息
Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States.
Veterinary Clinical Sciences, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Hong Kong, Hong Kong SAR, China.
出版信息
Front Vet Sci. 2025 Aug 20;12:1649751. doi: 10.3389/fvets.2025.1649751. eCollection 2025.
INTRODUCTION
Metabolic alkalosis induced by prepartum diet cations impairs Ca homeostasis in the periparturient cow. Adding anions to prepartum diets reduces blood pH improving periparturient Ca homeostasis. Urine pH generally reflects blood pH and is practical to measure on farm. The degree to which urine should be acidified to increase periparturient blood Ca concentration is not well defined.
MATERIALS AND METHODS
Prepartum urine pH and periparturient blood Ca concentrations determined in 660 multiparous Holstein cows from 9 studies were analyzed. Least Square Means of the lowest blood Ca concentration (Ca nadir) observed in cows within 6 urine pH categories (≤ 5.75, 5.76 to 6.25, 6.26 to 6.75, 6.76 to 7.25, 7.26 to 7.75, and ≥ 7.76) were determined. Data were analyzed across all 660 cows and then by parity.
RESULTS
Across all cows, the Ca nadir was lowest and the incidence of cows with Ca nadir < 2.00 mM, indicative of subclinical hypocalcemia (SCH), was greatest when urine pH was ≥ 7.76. Mean Ca nadir increased in all cows with urine pH < 7.75. There was no significant difference in Ca nadir or % of cows with SCH when prepartum urine pH was < 7.75. This was also the case for 2nd and 3rd parity cows. However, in ≥ 4th parity cows, those with urine pH between 6.26 and 6.75 had significantly higher Ca nadir than cows with urine pH above 7.25 or below 5.75. Calcium nadir and blood Ca concentrations at 2 days in milk (DIM) were highly correlated (r = + 0.58), and blood Ca concentrations at 2 and 4 DIM were moderately correlated (r = + 0.43). Blood Ca concentration at 4 DIM was weakly associated with Ca nadir (r = + 0.30).
DISCUSSION
These analyses support acidification of cows to achieve prepartum urine pH below 7.75 to increase blood Ca nadir for 2nd and 3rd parity cows. For ≥ 4th parity cows, the highest blood Ca nadir was observed with urine pH below 7.25 and above 5.75. For ≥ 4th parity cows, urine pH below 5.75 was associated with significantly lower blood Ca nadir.
引言
产前日粮阳离子诱导的代谢性碱中毒会损害围产期奶牛的钙稳态。在产前日粮中添加阴离子可降低血液pH值，改善围产期钙稳态。尿液pH值通常反映血液pH值，且在农场中易于测量。为提高围产期血液钙浓度而应将尿液酸化的程度尚不清楚。
材料与方法
分析了来自9项研究的660头经产荷斯坦奶牛的产前尿液pH值和围产期血液钙浓度。确定了6个尿液pH类别（≤5.75、5.76至6.25、6.26至6.75、6.76至7.25、7.26至7.75和≥7.76）的奶牛中观察到的最低血液钙浓度（钙最低点）的最小二乘均值。对所有660头奶牛的数据进行了分析，然后按胎次进行分析。
结果
在所有奶牛中，当尿液pH值≥7.76时，钙最低点最低，且钙最低点<2.00 mM（表明存在亚临床低钙血症（SCH））的奶牛发生率最高。尿液pH值<7.75的所有奶牛的平均钙最低点均升高。产前尿液pH值<7.75时，钙最低点或患SCH的奶牛百分比无显著差异。第二胎和第三胎奶牛也是如此。然而，在≥第四胎的奶牛中，尿液pH值在6.26至6.75之间的奶牛的钙最低点显著高于尿液pH值高于7.25或低于5.75的奶牛。产犊后2天（DIM）的钙最低点与血液钙浓度高度相关（r = +0.58），产犊后2天和4天的血液钙浓度中度相关（r = +0.43）。产犊后4天的血液钙浓度与钙最低点弱相关（r = +0.30）。
讨论
这些分析支持对奶牛进行酸化处理，以使产前尿液pH值低于7.75，从而提高第二胎和第三胎奶牛的血液钙最低点。对于≥第四胎的奶牛，尿液pH值低于7.25且高于5.75时观察到最高的血液钙最低点。对于≥第四胎的奶牛，尿液pH值低于5.75与显著更低的血液钙最低点相关。
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