Serum physiology, fecal microbiota, and metabolome signatures associated with perinatal stage transitions in Mongolian mares.

Overview

• This study investigated how Mongolian mares’ blood chemistry, gut bacteria, and fecal metabolites change during different stages around birth—before giving birth, immediately after, and early lactation.
• The goal was to understand how mares physiologically adapt during the perinatal period and to identify specific microbial and metabolic patterns associated with these stages.

Research Context and Purpose

• Lactation is crucial for offspring survival and overall livestock productivity in horses.
• Unlike ruminants, horses are monogastric herbivores with unique digestive systems, and little is known about how their gut microbiota change during perinatal physiological shifts.
• The study aimed to characterize serum physiological parameters, fecal microbiota composition, and fecal metabolite profiles to uncover stage-specific changes in multiparous Mongolian mares.

Methodology

• Subject: 19 multiparous Mongolian mares selected from a local herd, all with normal foaling and healthy weaning histories.
• Perinatal Stages: Three defined stages were studied—
  • Pre-foaling (PF): before giving birth
  • Post-foaling (PoF): immediately after delivery
  • Early lactation (EL): first phase of milk production
• Data Collected:
  • Serum biochemistry and reproductive hormones to assess physiological adaptation relevant to fetal development and lactogenesis.
  • Immune parameters, with a focus on immunoglobulin A (IgA) as a marker of mucosal immunity.
  • Fecal microbiota profiling to analyze bacterial community diversity and composition across stages.
  • Fecal metabolome analysis to identify metabolic changes correlating with gut microbial shifts.

Key Findings – Serum Physiology

• Pre-foaling period showed elevated serum levels of:
  • Triglycerides, urea, and mineral elements, potentially supporting fetal development.
• Post-foaling animals had increased serum glucose levels, likely reflecting the higher energy demands due to delivery and the start of lactation.
• Early lactation was marked by raised serum IgA concentrations, indicating heightened mucosal immune activity during this stage.
• Note: Serum IgA levels do not directly represent IgA levels in colostrum nor do they indicate the passive immunity transferred to foals.

Key Findings – Fecal Microbiota

• Alpha diversity (a measure of species richness and evenness) of gut microbiota was lowest during the post-foaling stage.
• Distinct microbial community structures were associated with each perinatal stage.
• Pre-foaling microbiota had higher abundance of bacteria linked to carbohydrate fermentation, supporting energy needs during gestation.
• Post-foaling microbial shifts showed increased abundance of bacteria potentially involved in intestinal barrier integrity (specific taxa not named in abstract), along with heightened galactose metabolism pathways suggested by predictive metagenomics (PICRUSt2 analysis).
• Early lactation microbiota were dominated by taxa related to lipid metabolism and bile secretion pathways, possibly adapting to nutrient processing for milk production.

Key Findings – Fecal Metabolome

• Metabolomic profiles in feces also changed distinctly with perinatal stages.
• These metabolic changes aligned with microbial shifts, indicating coordinated physiological modifications in the gut during gestation, delivery, and lactation.
• Specific fecal metabolites correlated with carbohydrate, lipid, and bile metabolism were identified as candidate markers of stage-specific adaptation.

Conclusions and Implications

• The study provided a comprehensive characterization of physiological, microbial, and metabolic adaptations in Mongolian mares across important reproductive stages.
• Identified serum, microbial, and metabolic features serve as candidate markers for understanding perinatal biological changes but require further validation before being considered definitive biomarkers.
• Findings may improve understanding of equine reproductive biology and could inform management strategies to optimize health and productivity in breeding mares.
• The research highlights the complex interplay between systemic physiology and gut microbial ecology during critical reproductive transitions in a monogastric herbivore.