Endometritis is the leading cause of subfertility in horses. Endometritis often starts as a physiological inflammatory response to sperm and bacteria contained in the semen, which self-resolves within 48 hours; in 20% of the mare population, this condition is associated with an unregulated uterine inflammatory response that leads to an unfavorable environment for an embryo and predisposes to chronic infectious endometritis and the development of fibrosis. Semen factors such as concentration and motility can affect post-breeding endometritis; anecdotally donkey sperm causes lower uterine inflammation and higher pregnancy rates than horse sperm in subfertile mares. The role of bacteria in uterine healthy including endometritis has been re-invented over the past few years due to significant changes in the techniques that allow the detection of a core uterine microbiota, without the necessity of performing standard microbiological techniques. The first systematic description of the core uterine microbiome in horses was recently published in 2022, a multicentric study conducted in the US and Australia. A core uterine microbiome characterized by high richness and low diversity is thought to be necessary for women to modulate inflammation, establish a pregnancy, and prevent uterine infections from pathogenic bacteria. In domesticated animals, there is scarce information on the functional role of the uterine microbiome. To compare the uterine inflammatory response in the presence of intraspecies and interspecies sperm and seminal plasma, markers of uterine inflammation (uterine fluid, uterine edema, cytokines) were assessed before and after the infusion with donkey and horse semen and seminal plasma; next, changes in the uterine microbiome over time, across treatments and based on the embryo recovery outcome were evaluated. The results showed that donkey seminal plasma has an anti-inflammatory composition and role on the mare endometrium and that the horse uterine microbiome fluctuates over time and in relation to the presence of an embryo. Collectively, the present findings suggest that the male seminal proteome, metabolome, and microbiome alter the mare uterine response and may have further trickle-down effects on physiological processes such as the response to semen or the early stages of embryonic development.Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2025-03-28 without embargo termsThe student, Giorgia Podico, accepted the attached license on 2024-12-03 at 16:16.The student, Giorgia Podico, submitted this Dissertation for approval on 2024-12-03 at 16:21.This Dissertation was approved for publication on 2024-12-04 at 18:24.DSpace SAF Submission Ingestion Package generated from Vireo submission #21384 on 2025-03-28 at 14:26:0
