Department of Production Animal Clinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Box 5003, 1432, Ås, Norway.
Department of Paraclinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Box 5003, 1432, Ås, Norway.
Theriogenology. 2023 Oct 1;209:115-125. doi: 10.1016/j.theriogenology.2023.06.024. Epub 2023 Jun 17.
The individual resistance or tolerance against uterine disease in dairy cattle might be related to variations in the uterine tract microbiota. The uterine tract microbiota in dairy cattle is a field of increasing interest. However, its specific taxonomy and functional aspects is under-explored, and information about the microbiota in the endometrium at artificial insemination (AI) is still missing. Although uterine bacteria are likely to be introduced via the vaginal route, it has also been suggested that pathogens can be transferred to the uterus via a hematogenous route. Thus, the microbiota in different layers of the uterine wall may differ. Norwegian Red (NR) is a high fertility breed that also has a high prevalence of subclinical endometritis (SCE), an inflammation of the uterus that has a negative effect on dairy cattle fertility. However, in this breed the negative effect is only moderate, raising the question of whether this may be due to a favorable microbiota. In the present study we investigated the endometrial microbiota in NR at AI by biopsy and cytobrush samples, and comparing this to the vaginal microflora. The second objective was to describe potential differences at both distinct depths of the endometrium, in healthy vs SCE positive NR cows. We sampled 24 lactating and clinically healthy Norwegian red cows in their second heat or more after calving, presented for first AI. First, we obtained a vaginal swab and a cytobrush sample, in addition to a cytotape to investigate the animal's uterine health status with respect to SCE. Secondly, we acquired a biopsy sample from the uterine endometrium. Bacterial DNA from the 16S rRNA gene was extracted and sequenced with Illumina sequencing of the V3-V4 region. Alpha and beta diversity and taxonomic composition was investigated. Our results showed that the microbiota of endometrial biopsies was qualitatively different and more even than that of cytobrush and vaginal swab samples. The cytobrush samples and the vaginal swabs shared a similar taxonomic composition, suggesting that vaginal swabs may suffice to sample the surface-layer uterine microbiota at estrus. The current study gave a description of the microbiota in the healthy and SCE positive NR cows at AI. Our results are valuable as we continue to explore the mechanisms for high fertility in NR, and possible further improvements.
奶牛个体对子宫疾病的抵抗力或耐受性可能与子宫腔微生物群的变化有关。奶牛的子宫腔微生物群是一个日益受到关注的领域。然而，其特定的分类学和功能方面尚未得到充分探索，并且在人工授精（AI）时子宫内膜的微生物组信息仍然缺失。虽然子宫细菌可能通过阴道途径引入，但也有人认为病原体可以通过血液途径转移到子宫。因此，子宫壁的不同层中的微生物组可能不同。挪威红牛（NR）是一个高繁殖力的品种，也有很高的亚临床子宫内膜炎（SCE）发病率，这会对奶牛的繁殖力产生负面影响。然而，在这个品种中，这种负面影响只是中等程度的，这就提出了一个问题，即这是否可能是由于有利的微生物组。在本研究中，我们通过活检和细胞刷样本研究了 NR 在 AI 时的子宫内膜微生物组，并将其与阴道微生物群进行了比较。第二个目的是描述健康 NR 牛与 SCE 阳性 NR 牛的子宫内膜在不同深度的潜在差异。我们从 24 头处于泌乳期且临床健康的挪威红牛牛中采样，这些牛在产犊后第二次发情或更多次发情，用于第一次 AI。首先，我们获得了阴道拭子和细胞刷样本，以及细胞带，以调查动物的子宫健康状况与 SCE 的关系。其次，我们从子宫子宫内膜采集了活检样本。从 16S rRNA 基因中提取细菌 DNA，并对 V3-V4 区域进行 Illumina 测序。研究了 alpha 和 beta 多样性以及分类组成。我们的结果表明，子宫内膜活检样本的微生物组在质量上与细胞刷和阴道拭子样本不同，并且更均匀。细胞刷样本和阴道拭子共享相似的分类组成，这表明阴道拭子可能足以在发情期取样表面层子宫微生物组。本研究描述了 AI 时健康和 SCE 阳性 NR 牛的微生物组。我们的结果很有价值，因为我们继续探索 NR 高繁殖力的机制，并可能进一步改进。
