Changes in Fecal Microbiota During Estrous Cycle in Healthy Thoroughbred Mares.

This research explores the impact of an estrous cycle on gut microbiota in healthy Thoroughbred mares, finding some correlation between sexual hormone fluctuations and the presence of certain bacteria.

Objective of the study

• The purpose of this work was to comprehend the association between cyclical variations in steroid sex hormones and the gut microbiome of mares. Steroid sex hormones such as estradiol-17β (E2) and progesterone (P4), usually change periodically throughout the normal estrous cycle in healthy mares. The influence of these changes on gut bacteria was analyzed.

Methodology

• Five healthy mares were the subjects of this study. Blood and fecal samples were obtained from these mares during their regular estrous cycle.
• To track the levels of E2 and P4 hormones in the mares’ serum, a Radioimmunoassay (RIA) was performed.
• The composition of the gut microbiota was established using 16S rRNA sequencing, a common method used to distinguish and classify microbes present in a sample.

Findings

• The analysis showed that, on the whole, the richness and composition of the gut microbiota stay relatively stable during the normal estrous cycle in mares.
• Linear Discriminant Analysis Effect Size was used to compare the microbial composition during the follicular and luteal phases of the estrous cycle. This process revealed the Rhodococcus genus as being differentially abundant in the two phases.
• The findings therefore demonstrate that the main composition of the mare’s gut microbiota does not change much throughout the estrous cycle, although specific low-abundance pathogenic bacteria exhibit changes in response to fluctuations in sexual hormone levels.