Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853.
Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853.
J Dairy Sci. 2023 Dec;106(12):9587-9597. doi: 10.3168/jds.2022-23175. Epub 2023 Sep 9.
Many multiparous dairy cows experience subclinical hypocalcemia (SCH) in the immediate postpartum period as they adapt to the demands of lactation. Furthermore, differing dynamics of SCH in the days following parturition are associated with varied health and production outcomes, with cows experiencing transient SCH producing more milk and facing fewer negative health events than cows with delayed or persistent SCH. Our objectives were to describe differences in mediators of calcium (Ca) homeostasis between cows experiencing differing Ca dynamics postpartum. A prospective cohort of 89 multiparous Holstein cows from 2 herds in New York were classified into 1 of 4 SCH groups based on mean serum total Ca (tCa) at 1 and 4 d in milk (DIM): normocalcemic (NC; [tCa] >1.89 mmol/L at 1 DIM and >2.25 mmol/L at 4 DIM, n = 30); transient SCH (tSCH; [tCa] ≤1.89 mmol/L at 1 DIM and >2.25 mmol/L at 4 DIM, n = 12); delayed SCH (dSCH; [tCa] >1.89 mmol/L at 1 DIM and ≤2.25 mmol/L at 4 DIM, n = 23); and persistent SCH (pSCH; [tCa] ≤1.89 mmol at 1 DIM and ≤2.25 mmol/L at 4 DIM, n = 24). Blood samples were collected at -5, -1, 1 through 5, 7, and 10 DIM and analyzed for tCa, parathyroid hormone (PTH), and serotonin. Repeated measures ANOVA models were used to analyze differences between SCH groups and changes over time for tCa, PTH, and serotonin. During the prepartum period, tCa was greater in the NC, tSCH, and dSCH cows as compared with the pSCH cows and there was marginal evidence for a difference in PTH between SCH groups. Postpartum tCa varied over time between SCH groups. Mean postpartum (95% confidence interval) tCa for respective SCH groups were NC = 2.32 (2.28, 2.35) mmol/L; tSCH = 2.20 (2.14, 2.25) mmol/L; dSCH = 2.17 (2.13, 2.21) mmol/L; and pSCH = 2.03 (1.99, 2.07) mmol/L. Mean concentrations of PTH in the postpartum period were NC = 70.1 (66.2, 74.4) pmol/L; tSCH = 72.1 (66.1, 79.2); dSCH = 75.8 (70.8, 81.5) pmol/L; and pSCH = 77.7 (72.4, 83.9) pmol/L. Serotonin was similar between SCH groups pre- and postpartum and followed a cyclical pattern from 1 to 10 DIM. Our results agreed with our hypothesis that differences in postpartum PTH might exist between cows experiencing different dynamics of SCH in the early lactation period; however, further studies are needed to confirm this difference. If true, this would suggest that Ca homeostasis may be disrupted in cows with dSCH and pSCH. Gaining a better understanding of these modulatory differences may aid in the prevention, management, and treatment of SCH.
许多经产奶牛在适应泌乳需求时会在产后立即经历亚临床低钙血症（SCH）。此外，产后不同时间 SCH 的动态变化与不同的健康和生产结果相关，经历短暂性 SCH 的奶牛产奶量更多，面临的负面健康事件也少于延迟或持续 SCH 的奶牛。我们的目的是描述产后不同 Ca 动态奶牛中钙（Ca）稳态调节剂的差异。来自纽约 2 个牛群的 89 头经产荷斯坦奶牛的前瞻性队列根据产后第 1 天和第 4 天的血清总钙（tCa）分为 4 个 SCH 组：正常钙血症（NC；[tCa]在第 1 天>1.89mmol/L，第 4 天>2.25mmol/L，n=30）；短暂性 SCH（tSCH；[tCa]在第 1 天≤1.89mmol/L，第 4 天>2.25mmol/L，n=12）；延迟性 SCH（dSCH；[tCa]在第 1 天>1.89mmol/L，第 4 天≤2.25mmol/L，n=23）；和持续性 SCH（pSCH；[tCa]在第 1 天≤1.89mmol/L，第 4 天≤2.25mmol/L，n=24）。在产后第-5、-1、1 天至 5、7 和 10 天采集血液样本，分析 tCa、甲状旁腺激素（PTH）和血清素。使用重复测量方差分析模型分析 SCH 组之间的差异以及 tCa、PTH 和血清素随时间的变化。在产前期间，与 pSCH 奶牛相比，NC、tSCH 和 dSCH 奶牛的 tCa 更高，SCH 组之间的 PTH 存在差异的证据不足。产后 tCa 在 SCH 组之间随时间变化。相应 SCH 组的产后平均（95%置信区间）tCa 为 NC=2.32（2.28，2.35）mmol/L；tSCH=2.20（2.14，2.25）mmol/L；dSCH=2.17（2.13，2.21）mmol/L；和 pSCH=2.03（1.99，2.07）mmol/L。产后 PTH 的平均浓度为 NC=70.1（66.2，74.4）pmol/L；tSCH=72.1（66.1，79.2）；dSCH=75.8（70.8，81.5）pmol/L；和 pSCH=77.7（72.4，83.9）pmol/L。SCH 组在产前和产后的血清素相似，从第 1 天到第 10 天呈周期性模式。我们的结果与我们的假设一致，即经历早期泌乳期不同 SCH 动态的奶牛之间可能存在产后 PTH 差异；然而，需要进一步的研究来证实这一差异。如果这是真的，这表明 dSCH 和 pSCH 奶牛的 Ca 稳态可能受到干扰。更好地了解这些调节差异可能有助于预防、管理和治疗 SCH。
