Abstract
BackgroundSubfertility is a major problem in modern horse breeding. Especially, mares without clinical signs of reproductive diseases, without known uterine pathogens and no evidence of inflammation but not becoming pregnant after several breeding attempts are challenging for veterinarians. To obtain new insights into the cause of these fertility problems and aiming at improving diagnosis of subfertile mares, a comparative analysis of the intrauterine transcriptome in subfertile and fertile mares was performed. Uterine cytobrush samples were collected during estrus from 57 mares without clinical signs of uterine diseases. RNA was extracted from the cytobrush samples and samples from 11 selected subfertile and 11 fertile mares were used for Illumina RNA-sequencing.ResultsThe cytobrush sampling was a suitable technique to isolate enough RNA of high quality for transcriptome analysis. Comparing subfertile and fertile mares, 114 differentially expressed genes (FDR = 10%) were identified. Metascape enrichment analysis revealed that genes with lower mRNA levels in subfertile mares were related to ‘extracellular matrix (ECM)’, ‘ECM-receptor interaction’, ‘focal adhesion’, ‘immune response’ and ‘cytosolic calcium ion concentration’, while DEGs with higher levels in subfertile mares were enriched for ‘monocarboxyl acid transmembrane transport activity’ and ‘protein targeting’.ConclusionOur study revealed significant differences in the uterine transcriptome between fertile and subfertile mares and provides leads for potential uterine molecular biomarkers of subfertility in the mare.
Highlights
Subfertility is a major problem in modern horse breeding
With the aim to improve the diagnosis of subfertile mares without clinical signs of uterine diseases and to characterize Ribonucleic acid (RNA) markers to predict fertility, our objective was to perform a comparative analysis of the intrauterine transcriptome at estrus of fertile and subfertile mares without clinical signs of uterine diseases
From each group of the fertile mares (FB-P) and subfertile mares (RB-N) 11 mares without facultative pathogens were selected for RNA sequencing
Summary
Mares without clinical signs of reproductive diseases, without known uterine pathogens and no evidence of inflammation but not becoming pregnant after several breeding attempts are challenging for veterinarians. Uterine cytobrush samples were collected during estrus from 57 mares without clinical signs of uterine diseases. Subfertile mares do either not conceive or require more examinations, inseminations and treatments to get pregnant than their fertile counterparts. Many factors such as age, reproductive status, gynecological health of the mare, sperm quality, sperm preservation and breeding management have an effect. Often endometritis can be diagnosed by detecting clinical signs, uterine inflammation in cytological examination or pathogens in uterine microbial culture [9]. Le Blanc and Causey [9] described these disturbances in fertility as hidden cases of endometritis or subclinical endometritis
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