Comparing microbiotas of foals and their mares' milk in the first two weeks after birth.
Authors: Mienaltowski Michael J, Callahan Mitchell, De La Torre Ubaldo, Maga Elizabeth A
Journal: BMC veterinary research
Summary
# Editorial Summary Understanding the microbial seeding of the foal's gastrointestinal tract during the critical first two weeks of life remains crucial for preventing early-life diarrhoea, particularly the common but poorly understood "foal heat diarrhoea" that coincides with the mare's postpartum oestrus cycle around day 6–10. Mienaltowski and colleagues investigated whether changes in lysozyme activity and microbial composition in mare's colostrum and milk might explain the gastrointestinal dysbiosis underlying this condition by sampling milk from 15 mares and rectal swabs from their foals every other day for the first 15 days post-foaling, then quantifying lysozyme using fluorescence assays and characterising bacterial populations through 16S rRNA gene sequencing. The researchers identified distinct temporal shifts in both the protective antimicrobial proteins in milk and the foal's developing microbiota, with lysozyme levels and bacterial diversity patterns changing significantly across the sampling period in ways that correlated between dam and offspring. These findings suggest that the transition from colostrum to mature milk—and associated changes in its immunological and microbial components—directly influences microbial colonisation of the foal's gut and may predispose to dysbiosis-related diarrhoea. For practitioners managing neonatal foals, this work underscores the importance of monitoring early milk composition and foal GI health as linked processes, potentially informing prophylactic nutritional or probiotic interventions during the high-risk second week of life.
Read the full abstract on PubMed
Practical Takeaways
- •Monitor foals closely for diarrhea in the first two weeks, especially around mare estrus (day 7-10), as this reflects normal but significant GI microbiota shifts rather than infection alone
- •Mare's milk composition changes dynamically in early lactation—maintaining foal-mare contact and nursing frequency supports natural microbiota establishment
- •Understanding that foal heat diarrhea is linked to microbiota transition rather than solely pathogenic infection may influence management decisions about antimicrobial use in affected foals
Key Findings
- •Mare's milk microbiota and lysozyme activity change significantly during the first 15 days postpartum, coinciding with foal GI microbiota transitions
- •Rectal swab microbial composition in foals shows dynamic shifts in the first two weeks of life that correlate with milk microbial changes
- •Lysozyme activity in mare's milk fluctuates during early lactation, potentially influencing foal GI colonization patterns
- •Changes in milk microbiota composition may explain the timing and occurrence of foal heat diarrhea during the neonatal period