Department of Animal Sciences, University of Florida, Gainesville 32611.
Swansea University Medical School, Swansea University, Swansea, United Kingdom, SA2 8PP.
J Dairy Sci. 2023 Jun;106(6):4198-4213. doi: 10.3168/jds.2022-22846. Epub 2023 Apr 18.
Objectives of this experiment were to study the effect of infusing utero-pathogenic bacteria to induce endometrial inflammation on productive performance in early lactation and subsequent reproduction. Although endometritis is associated with perturbed reproduction, numerous factors may contribute to the observed association. It was hypothesized that induced endometrial inflammation, resulting in localized and systemic inflammatory responses, compromises production and reproduction. Holstein cows without clinical disease and with less than 18% polymorphonuclear leukocytes (PMN) in endometrial cytology on d 31 ± 3 postpartum had their estrous cycle synchronized. Cows were blocked by parity and genomic breeding value for cow conception rate and, within block, assigned randomly to remain as untreated controls (CON; n = 37) or to receive an intrauterine infusion of 5.19 × 10 cfu Escherichia coli and 4.34 × 10 cfu Trueperella pyogenes during the luteal phase to induce endometrial inflammation (INF; n = 48). Endometrial cytology was taken on d 2 and 7 after treatment to evaluate the proportion of PMN. Rectal temperature, dry matter intake, and yields of milk and components were measured in the first 7 d after treatment. Blood serum was analyzed for concentration of haptoglobin. Leukocytes were isolated from blood on d 2 and 7 after treatment and on d 19 after artificial insemination (AI) and mRNA was quantified for a select group of genes. Cows received AI and reproduction was followed for 300 d postpartum. Bacterial infusion induced endometrial inflammation with increased proportions of PMN in the endometrial cytology on d 2 (4.4 ± 0.7 vs. 26.3 ± 2.8%) and 7 (10.9 ± 1.7 vs. 17.4 ± 2.1%) after treatment, resulting in increased mean prevalence of subclinical endometritis (>10% PMN; 23.3 ± 6.3 vs. 80.9 ± 5.1%). Rectal temperature did not differ between CON and INF, but the concentration of haptoglobin in serum tended to increase in INF compared with CON (113 ± 14 vs. 150 ± 16 µg/mL). Induced endometrial inflammation reduced yields of milk (44.9 ± 0.8 vs. 41.6 ± 0.8 kg/d), protein (1.19 ± 0.03 vs. 1.12 ± 0.03 kg/d), and lactose (2.17 ± 0.04 vs. 2.03 ± 0.04 kg/d) and tended to reduce dry matter intake (20.7 ± 0.5 vs. 19.4 ± 0.6 kg/d) in the first 7 d after treatment. Indeed, the reduction in milk yield lasted 4 wk. However, treatment did not affect yields of energy-corrected milk or fat because treatment with INF increased the concentration of fat in milk (3.54 ± 0.10 vs. 3.84 ± 0.10%). Induced endometrial inflammation reduced pregnancy per AI at all inseminations (33.4 ± 5.1 vs. 21.6 ± 3.7%) and the hazard of pregnancy (0.61; 95% CI = 0.36-1.04), which extended the median days open by 24 d. Blood leukocytes from INF cows had increased mRNA expression of the pro-inflammatory gene IL1B on d 2 and 7 after treatment, but reduced expression of the IFN-stimulated genes ISG15 and MX2 on d 19 after AI. Induced endometrial inflammation depressed production and caused long-term negative effects on reproduction in lactating dairy cows.
本实验的目的是研究宫内致病性细菌诱导子宫内膜炎对泌乳早期生产性能和随后繁殖的影响。尽管子宫内膜炎与繁殖功能障碍有关，但许多因素可能导致观察到的相关性。据假设，诱导的子宫内膜炎导致局部和全身炎症反应，从而损害生产和繁殖。无临床疾病且产后第 31 天 ± 3 天子宫内膜细胞学中多形核白细胞（PMN）<18%的荷斯坦奶牛同步发情周期。根据奶牛受孕率的产犊数和基因组育种值将奶牛分组，并在分组内随机分配，以保持未处理对照（CON；n=37）或在黄体期宫内输注 5.19×10 cfu 大肠杆菌和 4.34×10 cfu 坏死梭杆菌以诱导子宫内膜炎（INF；n=48）。治疗后第 2 天和第 7 天取子宫内膜细胞学样本，以评估PMN 的比例。治疗后第 1 天测量直肠温度、干物质采食量以及牛奶和成分的产量。治疗后第 2 天和第 7 天以及人工授精（AI）后第 19 天从血液中分离白细胞，并定量选择一组基因的 mRNA。奶牛接受 AI 并在产后 300 天内进行繁殖跟踪。细菌输注诱导子宫内膜炎，子宫内膜细胞学中PMN 的比例在第 2 天（4.4±0.7% vs. 26.3±2.8%）和第 7 天（10.9±1.7% vs. 17.4±2.1%）升高，导致亚临床子宫内膜炎的平均患病率增加（>10%PMN；23.3±6.3% vs. 80.9±5.1%）。CON 和 INF 之间直肠温度没有差异，但与 CON 相比，INF 中血清中 haptoglobin 的浓度有升高趋势（113±14 vs. 150±16 µg/mL）。诱导的子宫内膜炎降低了牛奶（44.9±0.8 vs. 41.6±0.8 kg/d）、蛋白质（1.19±0.03 vs. 1.12±0.03 kg/d）和乳糖（2.17±0.04 vs. 2.03±0.04 kg/d）的产量，并在治疗后第 1 天至第 7 天有降低干物质采食量的趋势（20.7±0.5 vs. 19.4±0.6 kg/d）。事实上，牛奶产量的减少持续了 4 周。然而，治疗并未影响能量校正奶或脂肪的产量，因为 INF 治疗增加了牛奶中的脂肪浓度（3.54±0.10 vs. 3.84±0.10%）。诱导的子宫内膜炎降低了所有授精时的妊娠/AI 率（33.4±5.1% vs. 21.6±3.7%）和妊娠的危害（0.61；95%CI=0.36-1.04），这将开放天数中位数延长了 24 天。INF 奶牛的血液白细胞在治疗后第 2 天和第 7 天的促炎基因 IL1B 的 mRNA 表达增加，但在 AI 后第 19 天的 IFN 刺激基因 ISG15 和 MX2 的表达减少。诱导的子宫内膜炎抑制了生产，并对泌乳奶牛的繁殖产生了长期的负面影响。
