# Feeding a Saccharomyces cerevisiae Fermentation Product to Mares in Late Gestation Alters the Biological Activity of Colostrum

## TL;DR

Feeding a yeast supplement to pregnant mares improves the biological activity of their colostrum, which may boost foals' immune responses later in life.

## Contribution

This study shows that a Saccharomyces cerevisiae fermentation product can enhance colostrum activity, affecting foal immune responses.

## Key findings

- Colostrum from SCFP-fed mares showed higher growth-promoting activity in cell assays.
- Biological activity of colostrum correlated with vaccine-induced changes in foal blood composition.
- SCFP supplementation did not affect IgG levels or mares' early vaccination response.

## Abstract

To ensure adequate immune protection, foals are dependent on a sufficient intake of good quality colostrum shortly after birth. In this study we analyzed whether a supplemented Saccharomyces cerevisiae fermentation product (SCFP) to mares in late gestation alters the biological activity of their colostrum and whether the uptake of such a colostrum affects the immediate response to vaccination at the age of 5 to 8 months. Twenty-six pregnant mares were randomly assigned to receive either a supplement or no supplementation twelve weeks before the calculated date of birth. Mares were actively vaccinated three weeks before parturition with a commercial influenza and tetanus vaccine. Their foals were actively vaccinated against equine influenza and tetanus after weaning. Blood cell composition was determined directly before vaccination and 24 h later. The biological activity of colostrum samples was assessed in a cell viability assay with an intestinal epithelial cell line. Colostrum from SCFP-fed mares exhibited significantly higher growth-promoting activity compared to control mares. While SCFP feeding did not affect the early vaccination response of mares, the biological activity of colostrum had a significant effect on vaccine-induced changes in blood composition of weanling foals. Therefore, a Saccharomyces cerevisiae fermentation product supplement may improve the biological activity of colostrum, which affects innate immune responses of foals.

The quality of equine colostrum is typically defined by refractometry or the concentration of maternal antibodies. However, the activity of other equine colostral bioactive molecules has not yet been investigated. This study analyzed whether the administration of a Saccharomyces cerevisiae fermentation product (SCFP) influences the biological activity of mare colostrum and whether the biological activity of colostrum has a lasting immunomodulating effect for foals. A total of fourteen pregnant mares received 20 g/day of a SCFP for a period of twelve weeks prior to the calculated date of birth (SCFP-group). Twelve pregnant mares without supplementation served as controls (CON). Colostral Brix values were determined within three hours after parturition. The concentration of IgG in blood sera and colostrum samples was determined with an ELISA. The biological activity was determined in a cell growth assay with a porcine epithelial cell line (IPEC-J2). Mares (at three weeks before the calculated date of birth) and foals (at the age of 5–8 months) received a parenteral active vaccination against influenza and tetanus. The administration of SCFP did not alter the mare’s serum and colostrum IgG concentrations and did not exert a significant influence on the mares’ early response to the vaccination. Growth and diarrhea episodes were comparable between foals of supplemented mares (SCFP) and foals of mares without supplementation (CON). Colostrum samples from SCFP-supplemented mares exhibited heightened biological activity. While SFCP and CON foals did not differ in their early response to vaccination, the vaccination-induced alterations in circulating neutrophilic granulocyte numbers were significantly correlated with the biological colostrum activity. These findings suggest that the supplementation of mares in late gestation with SCFP can enhance the biological activity of colostrum, which subsequently influences the innate immune responses of their offspring in later life.