Veterinary Physiology, Vetsuisse Faculty, University of Bern, CH-3012 Bern, Switzerland.
Veterinary Physiology, Vetsuisse Faculty, University of Bern, CH-3012 Bern, Switzerland.
J Dairy Sci. 2020 Jun;103(6):5604-5615. doi: 10.3168/jds.2019-18032. Epub 2020 Apr 3.
Infections of the mammary gland in dairy cows are commonly accompanied by reduced milk production and feed intake and poor milk quality. The metabolic status of early-lactating cows is known to affect immune response to pathogens and imposed immune challenges. We investigated the extent to which metabolic status before an intramammary lipopolysaccharide (LPS) challenge (LPS-CH) is associated with immune response, milk production, and feed intake and the recovery thereof. In 15 Holstein cows, weekly blood sampling and daily recording of dry matter intake, milk yield, milk composition, and body weight (to calculate energy balance) was started immediately after parturition. In wk 4 after parturition, cows underwent an intramammary LPS-CH (50 μg of LPS into 1 quarter). Blood and milk samples were taken in parallel at 30- and 60-min intervals, respectively, until 10 h after the LPS application. Plasma concentrations of glucose, nonesterified fatty acids, β-hydroxybutyrate (BHB), cortisol, and insulin were analyzed. In milk, serum albumin, IgG concentration, somatic cell count (SCC), and lactate dehydrogenase (LDH) activity were determined. Dry matter intake and milk yield were recorded for an additional 6 d. Milk of the LPS-treated quarter was sampled at every milking for 8 d after the challenge. Based on plasma glucose concentrations in wk 1 to 4 after parturition before the LPS-CH, cows were retrospectively grouped into a high-glucose group (HG; 3.34-3.93 mmol/L, n = 7) and a low-glucose group (LG; 2.87-3.31 mmol/L, n = 8). Data were evaluated using mixed models with time, group, and time × group interaction as fixed effects and cow as repeated subject. Glucose was lower and BHB was higher in LG compared with HG before LPS-CH, whereas dry matter intake, energy balance, and SCC did not differ. During LPS-CH, SCC and LDH increased similarly in HG and LG, body temperature increased less in HG, and BHB and nonesterified fatty acids were higher in LG compared with HG. Dry matter intake declined in both groups during the day of the LPS-CH but recovered to prechallenge values faster in HG. Milk yield recovered within 2 d after the LPS-CH with no differences in morning milkings, whereas evening milk yield increased faster in HG. During 8 d after LPS-CH, SCC, LDH, IgG, and serum albumin in milk were lower in HG compared with LG. In conclusion, the level of circulating glucose and BHB concentrations in cows was associated with metabolic responses during an LPS-CH as well as the recovery of udder health and performance thereafter.
奶牛乳房感染通常伴随着产奶量和采食量减少以及牛奶质量下降。初产奶牛的代谢状况已知会影响对病原体的免疫反应和施加的免疫挑战。我们研究了在脂多糖（LPS）挑战（LPS-CH）之前的代谢状况与免疫反应、产奶量和采食量及其恢复之间的关联程度。在 15 头荷斯坦奶牛中，每周进行一次血液采样，并在分娩后立即开始每天记录干物质摄入量、产奶量、牛奶成分和体重（以计算能量平衡）。分娩后第 4 周，奶牛接受了一次乳房内 LPS-CH（将 50 μg LPS 注入 1 个象限）。在 LPS 应用后 30 分钟和 60 分钟分别采集血液和牛奶样本，直到 LPS 应用后 10 小时。分析血浆中葡萄糖、非酯化脂肪酸、β-羟丁酸（BHB）、皮质醇和胰岛素的浓度。在牛奶中，测定血清白蛋白、IgG 浓度、体细胞计数（SCC）和乳酸脱氢酶（LDH）活性。在挑战后另外 6 天记录干物质摄入量和产奶量。在挑战后 8 天，每隔一次挤奶，从 LPS 处理的象限中采集牛奶。基于分娩后第 1 周到第 4 周血浆葡萄糖浓度，奶牛在 LPS-CH 前被回顾性地分为高葡萄糖组（HG；3.34-3.93 mmol/L，n=7）和低葡萄糖组（LG；2.87-3.31 mmol/L，n=8）。使用混合模型评估数据，时间、组和时间×组交互作用作为固定效应，牛作为重复个体。与 HG 相比，LG 在 LPS-CH 前的葡萄糖水平较低，BHB 水平较高，而干物质摄入量、能量平衡和 SCC 没有差异。在 LPS-CH 期间，HG 和 LG 的 SCC 和 LDH 增加相似，HG 的体温升高较少，LG 的 BHB 和非酯化脂肪酸水平高于 HG。两组在 LPS-CH 当天的干物质摄入量均下降，但 HG 更快地恢复到挑战前的值。在 LPS-CH 后 2 天内，产奶量恢复，早上挤奶没有差异，而 HG 的晚间产奶量增加更快。在 LPS-CH 后 8 天内，HG 的 SCC、LDH、IgG 和血清白蛋白在牛奶中的含量低于 LG。总之，奶牛循环葡萄糖和 BHB 浓度水平与 LPS-CH 期间的代谢反应以及随后乳房健康和性能的恢复有关。
