Dairy and Swine Research and Development Centre, Agriculture and Agri-Food Canada, 2000 College, Sherbrooke, QC, Canada J1M 0C8.
J Dairy Sci. 2012 Feb;95(2):708-17. doi: 10.3168/jds.2011-4695.
The periparturient period is marked by metabolic, hormonal, and immunological changes, which have an effect on the incidence of infectious and metabolic diseases. In a previous study, a slower increase in milk production was induced by milking cows once daily during the first week of lactation, leading to an improvement in levels of several metabolites, including nonesterified fatty acids (NEFA) and β-hydroxybutyrate (BHBA). The aim was to determine the influence of serum collected on d 2, 5, and 61 postpartum from cows milked once or twice daily on immune cell functions and to determine which of the constituents were responsible for these effects. Peripheral blood mononuclear cells (PBMC) and polymorphonuclear leukocytes were collected from healthy midlactation cows and their immune functions (i.e., proliferation and interferon-γ production and chemotaxis, phagocytosis, and oxidative burst, respectively), were evaluated in presence of serum, NEFA, and BHBA. Proliferation of PBMC was greater with d-61 (65.1±1.6%) serum than with d-2 (37.3±2.4%) or d-5 (48.4±1.6%) serum and greater with d-2 and -5 serum from cows milked once (42.2±3.7 and 54.0±2.5) compared with cows milked twice daily (32.4±3.0 and 42.9±2.1). Proliferation was inversely correlated with the concentration of NEFA and BHBA in the serum (r=-0.86). Adding NEFA to d-61 serum to reach the level present in d-5 serum decreased proliferation to the level observed with d-5 serum. No effect of BHBA addition was observed. The release of interferon-γ by PBMC was lower in d-5 serum (766±63 pg/mL) than in d-61 serum (1,187±90 pg/mL) and by NEFA. Milking frequency did not affect chemotaxis, phagocytosis, or oxidative burst of polymorphonuclear leukocytes. Phagocytosis decreased over time in serum from d 2 to 61. Similarly, oxidative burst was greater with d-5 serum (12.7×10(8) ± 1.6×10(8) relative light units) than with d-61 serum (9.0×10(8) ± 1.6×10(8) relative light units). The NEFA had a negative effect on oxidative burst, but BHBA did not. In conclusion, several immune cell functions appear affected by the NEFA concentration. Therefore, strategies that prevent increases in blood NEFA during the transition period may limit postpartum immunosuppression.
围产期伴随着代谢、激素和免疫变化，这些变化会影响传染病和代谢疾病的发病率。在之前的一项研究中，奶牛在泌乳的第一周每天挤奶一次，导致产奶量的增长速度放缓，从而改善了几种代谢物的水平，包括非酯化脂肪酸（NEFA）和β-羟丁酸（BHBA）。本研究旨在确定在产后第 2、5 和 61 天采集的每天挤奶 1 次或 2 次的奶牛血清对免疫细胞功能的影响，并确定是哪些成分导致了这些影响。从中性粒细胞（PMN）和外周血单核细胞（PBMC）采集健康泌乳中期奶牛的免疫功能（即增殖和干扰素-γ的产生和趋化性、吞噬作用和氧化爆发），并在血清、NEFA 和 BHBA 的存在下分别评估。与产后第 2 天（37.3±2.4%）或第 5 天（48.4±1.6%）血清相比，产后第 61 天（65.1±1.6%）血清对 PBMC 的增殖作用更大，且与每天挤奶 1 次的奶牛相比，产后第 2 天和第 5 天的血清（42.2±3.7 和 54.0±2.5）的增殖作用更大，而每天挤奶 2 次的奶牛的血清（32.4±3.0 和 42.9±2.1）的增殖作用则更小。增殖作用与血清中 NEFA 和 BHBA 的浓度呈负相关（r=-0.86）。将 NEFA 添加到产后第 61 天的血清中，使其达到产后第 5 天血清中的水平，将增殖作用降低到与产后第 5 天血清中相同的水平。添加 BHBA 则没有观察到影响。PBMC 释放的干扰素-γ在产后第 5 天血清（766±63 pg/mL）中低于产后第 61 天血清（1187±90 pg/mL）和 NEFA。产奶频率不影响 PMN 的趋化性、吞噬作用或氧化爆发。血清中吞噬作用从第 2 天到第 61 天逐渐下降。同样，产后第 5 天血清的氧化爆发（12.7×10(8)±1.6×10(8)相对光单位）大于产后第 61 天血清（9.0×10(8)±1.6×10(8)相对光单位）。NEFA 对氧化爆发有负面影响，但 BHBA 没有。总之，几种免疫细胞功能似乎受到 NEFA 浓度的影响。因此，在过渡期防止血液中 NEFA 增加的策略可能会限制产后免疫抑制。
