Department of Animal Science, Iowa State University, Ames 50011.
Department of Animal Science, South Dakota State University, Brookings 57006.
J Dairy Sci. 2019 Apr;102(4):3569-3583. doi: 10.3168/jds.2018-15631. Epub 2019 Feb 7.
Lipopolysaccharide (LPS) administration causes immunoactivation, which negatively affects production and fertility, but experimental exposure via an acute bolus is unlikely to resemble natural infections. Thus, the objectives were to characterize effects of chronic endotoxemia on production parameters and follicular development in estrous-synchronized lactating cows. Eleven Holstein cows (169 ± 20 d in milk; 681 ± 16 kg of body weight) were acclimated to their environmental surroundings for 3 d and then enrolled in 2 experimental periods (P). During P1 (3 d) cows consumed feed ad libitum and baseline samples were obtained. During P2 (7 d), cows were assigned to continuous infusion of either (1) saline-infused and pair-fed (CON-PF; 40 mL/h of saline i.v.; n = 5) or (2) LPS infused and ad libitum fed (LPS-AL; Escherichia coli O55:B5; 0.017, 0.020, 0.026, 0.036, 0.055, 0.088, and 0.148 μg/kg of body weight/h i.v. on d 1 to 7, respectively; n = 6). Controls were pair-fed to the LPS-AL group to eliminate confounding effects of dissimilar nutrient intake. Infusing LPS temporally caused mild hyperthermia on d 1 to 3 (+0.49°C) relative to baseline. Dry matter intake of LPS-AL cows decreased (28%) on d 1 of P2, then progressively returned to baseline. Relative to baseline, milk yield from LPS-AL cows was decreased on d 1 of P2 (12%). No treatment differences were observed in milk yield during P2. Follicular growth, dominant follicle size, serum progesterone (P4), and follicular P4 and 17β-estradiol concentrations were similar between treatments. Serum 17β-estradiol tended to increase (115%) and serum amyloid A and LPS-binding protein were increased (118 and 40%, respectively) in LPS-AL relative to CON-PF cows. Compared with CON-PF, neutrophils in LPS-AL cows were initially increased (45%), then gradually decreased. In contrast, monocytes were initially decreased (40%) and progressively increased with time in the LPS-AL cows. Hepatic mRNA abundance of cytochrome P450 family 2 subfamily C (CYP2C) or CYP3A was not affected by LPS, nor was there a treatment effect on toll-like receptor 4 or LBP; however, acyloxyacyl hydrolase and RELA subunit of nuclear factor kappa B tended to be increased in LPS-AL cows. These data suggest lactating dairy cows become tolerant to chronic and exponentially increasing LPS infusion in terms of production and reproductive parameters.
脂多糖（LPS）的给药会引起免疫激活，这会对生产和繁殖产生负面影响，但通过急性弹丸式给药进行的实验暴露不太可能类似于自然感染。因此，本研究的目的是描述慢性内毒素血症对发情同步泌乳奶牛生产参数和卵泡发育的影响。11 头荷斯坦奶牛（泌乳 169±20 天；体重 681±16kg）适应环境 3 天，然后进入 2 个实验期（P）。在 P1（3 天）期间，奶牛自由采食，采集基线样品。在 P2（7 天）期间，奶牛被分配到连续输注以下两种方案之一：（1）生理盐水输注和等量喂养（CON-PF；40mL/h 静脉内生理盐水；n=5）或（2）脂多糖输注和自由采食（LPS-AL；大肠杆菌 O55:B5；0.017、0.020、0.026、0.036、0.055、0.088 和 0.148μg/kg 的体重/小时静脉内输注，分别于第 1 至 7 天；n=6）。对照组与 LPS-AL 组等量喂养，以消除营养摄入不同的混杂影响。在第 1 至 3 天，与基线相比，LPS 的输注会导致体温短暂升高（0.49°C）。在 P2 的第 1 天，LPS-AL 奶牛的干物质摄入量下降（28%），然后逐渐恢复到基线。与基线相比，在 P2 的第 1 天，LPS-AL 奶牛的产奶量下降（12%）。在 P2 期间，两组之间的产奶量没有差异。卵泡生长、优势卵泡大小、血清孕酮（P4）、卵泡内 P4 和 17β-雌二醇浓度在处理之间相似。与 CON-PF 奶牛相比，LPS-AL 奶牛的血清 17β-雌二醇水平有升高趋势（115%），血清淀粉样蛋白 A 和脂多糖结合蛋白升高（分别为 118%和 40%）。与 CON-PF 相比，LPS-AL 奶牛的中性粒细胞最初增加（45%），然后逐渐减少。相反，单核细胞最初减少（40%），并随时间在 LPS-AL 奶牛中逐渐增加。LPS 对细胞色素 P450 家族 2 亚家族 C（CYP2C）或 CYP3A 的肝 mRNA 丰度没有影响，也没有对 Toll 样受体 4 或 LBP 产生治疗作用；然而，脂氧合酶和核因子 kappa B 的 RELA 亚基在 LPS-AL 奶牛中趋于增加。这些数据表明，泌乳奶牛在生产和繁殖参数方面对内毒素的慢性和指数增加输注具有耐受性。
