De Silva Malshani, Wickramasingha Devinda, Abayalath Nirodha, Alexander Basil, Wijayagunawardane Missaka, Lee Kai Fai, Kodithuwakku Suranga
Department of Animal Science, Faculty of Agriculture, University of Peradeniya, Peradeniya, 20400, Sri Lanka.
Department of Pharmacy, Faculty of Allied Health Sciences, University of Ruhuna, Galle, 80000, Sri Lanka.
BMC Vet Res. 2024 Dec 20;20(1):572. doi: 10.1186/s12917-024-04438-5.
Reproductive efficiency is paramount in the dairy industry, where early pregnancy detection of dairy cows will allow to detect the non-pregnant animals early, thus enabling to re-synchronize them and getting them pregnant leading to decrease in calving interval, which, in turn, is critical for maximizing productivity and economic gain. The objective of this study was to evaluate the colour Doppler ultrasonography (CDUS) and peripheral blood leukocytes (PBLs)-based pregnancy-associated biomarker mRNAs expression for the earliest detection of pregnancy status in the dairy cows at post insemination. Intensively managed animals were ovulation synchronized and subjected to timed artificial insemination (TAI). On day 20, corpus luteum blood flow (CLBF) was evaluated using CDUS in 30 cows. The percentage of the incoming blood flow (as an area) of the corpus luteum (CL) was determined using an image analysis software. On day 35, the same operator performed a final pregnancy diagnosis using transrectal ultrasonography to confirm the pregnancy. Blood samples were collected on day 20 and 28 after TAI for biomarkers analysis. The mRNA expression levels of ISG15, MX1, MX2, and PAG9 genes in PBLs were determined by quantitative polymerase chain reaction (qPCR).
The identified CLBF cutoff point resulted 100% sensitivity and negative predictive value (NPV) in determining non-pregnant status on day 20 in the cows. Overall, MX2 and ISG15 mRNAs showed the most significant (P < 0.05) expression levels in pregnant animals on day 20 and 28 compared to non-pregnant animals. Among them, MX2 showed the highest expression levels on both days, ascertaining it as the better candidate biomarker for the earliest identification of pregnancy.
The CDUS-based CLBF analysis on day 20 after TAI can be potentially used for the early identification of non-pregnancy status in dairy cows and MX2 could be a potential mRNA candidate for the identification of pregnancy in cows. Further studies should be conducted in large scale to validate these findings due to the small sample number used in the current study.
繁殖效率在奶牛养殖业中至关重要，早期检测奶牛怀孕情况能够尽早发现未怀孕的奶牛，从而使其重新同步发情并受孕，进而缩短产犊间隔，这对于最大化生产力和经济效益至关重要。本研究的目的是评估基于彩色多普勒超声（CDUS）和外周血白细胞（PBLs）的妊娠相关生物标志物mRNA表达，以在授精后最早检测奶牛的妊娠状态。对集约化管理的动物进行排卵同步，并进行定时人工授精（TAI）。在第20天，使用CDUS评估30头奶牛的黄体血流（CLBF）。使用图像分析软件确定黄体（CL）的流入血流百分比（作为面积）。在第35天，由同一名操作人员使用经直肠超声进行最终妊娠诊断以确认妊娠情况。在TAI后的第20天和第28天采集血样进行生物标志物分析。通过定量聚合酶链反应（qPCR）测定PBLs中ISG15、MX1、MX2和PAG9基因的mRNA表达水平。
所确定的CLBF临界点在第20天确定奶牛未怀孕状态时具有100%的敏感性和阴性预测值（NPV）。总体而言，与未怀孕动物相比，MX2和ISG15 mRNA在怀孕动物的第20天和第28天显示出最显著（P < 0.05）的表达水平。其中，MX2在这两天均显示出最高表达水平，确定其为最早识别妊娠的更好候选生物标志物。
TAI后第20天基于CDUS的CLBF分析可潜在用于早期识别奶牛的未怀孕状态，MX2可能是识别奶牛妊娠的潜在mRNA候选物。由于本研究使用的样本数量较少，应进行大规模进一步研究以验证这些发现。
