Study 1 - Publication 1

A Saccharomyces cerevisiae Fermentation Product (Olimond BB) Alters the Early Response after Influenza Vaccination in Racehorses

Vaccination is one of the most important prophylactic methods for the prevention of disease in veterinary medicine. The initial post-vaccination events are dominated by innate immune mechanisms leading to a coordinated activation of specific adaptive immune responses. Thus, antibody production and induction of specific T cells depend on early post-vaccination events, triggered by vaccine ingredients and guided by factors released from initially targeted tissues and cells. 

The aim of this study was to analyse whether feeding a pre- and postbiotic feed supplement modulates such early immune responses after vaccination. 

Horses were fed a supplement (Olimond BB) based on products of fermented yeasts (Saccharomyces cerevisiae) for 8 weeks and subsequently vaccinated against influenza. Circulating leukocyte counts and their subpopulations were determined before and 24 h after vaccination. 

In absence of vaccination-induced side effects, horses receiving the supplement differed from control horses in the composition of neutrophilic granulocytes, CD4+ cells, and reticulocytes. 

Thus, the pre- and post-biotic feed supplement modulated early innate immune mechanisms after vaccination.

To the paper

Study 1 – Publication 2

Feeding a Saccharomyces cerevisiae Fermentation Product (Olimond BB) Does Not Alter the Fecal Microbiota of Thoroughbred Racehorses

Saccharomyces cerevisiae fermentation products (SCFP) are feed supplements and are widely used in animal nutrition to promote health. The biological effects of SCFP are based on prebiotic mechanisms that directly influence the microbial community of the gut microbiome or postbiotic factors that directly interact with host cells. 

To show whether the immunomodulatory effects of SCFP feeding are due to an altered composition of gut microbiota, we analyzed the fecal microbiota of racehorses. 

Horses were fed either the SCFP (Olimond BB) or a placebo product for six weeks, and fecal samples were collected for 16S rRNA gene sequencing. During this period, SCFP feeding only subtly affected the fecal microbiota in bacterial composition and diversity. SCFP and placebo horses differed significantly in the fecal bacterial diversity directly after intramuscular influenza vaccination. 

Altogether, the findings argue against a strong prebiotic effect of SCFP in racehorses. In contrast, the modulation of vaccine- and host-induced alterations of the microbiome suggests that the main effects of SCFP are due to contained or induced postbiotic components.

To the paper

Study 2 - Publication 1

Supplementation of Foals with a Saccharomyces cerevisiae Fermentation Product Alters the Early Response to Vaccination

Many foals suffer from foal heat diarrhea in the first weeks of life. The objective of this study was to determine whether feeding a Saccharomyces cerevisiae fermentation product affects the occurrence of early foal diarrhea, and whether this feeding during the first four weeks of life has a long-term influence on the immediate response to a parenteral vaccination at the age of 6 to 9 months. 

Newborn foals were fed a supplement or a placebo for 29 days and were vaccinated against influenza and tetanus in the age of 6–9 months. Blood leukocyte subset numbers were determined before and 24 h after vaccination. 

Leukocyte numbers and blood cell composition did not differ significantly between the supplemented group and the placebo group on the day of vaccination, whereas only supplemented foals showed significant changes in the number of circulating leukocyte populations after vaccination. 

Thus, the pre- and postbiotic supplementation had far-reaching consequences for innate immune mechanisms later in life.

To the paper

Study 2 - Publication 2

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

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.

To the paper

Doctoral thesis

Result from study 1

Der Einfluss eines Saccharomyces cerevisiae Fermentationsproduktes (Olimond BB) auf die fäkale Mikrobiota und das Immunsystem bei Rennpferden

Saccharomyces cerevisiae Fermentationsprodukte (SCFP) werden in der Tierhaltung als prä- und postbiotische Futterzusätze eingesetzt, mit dem Ziel die Allgemeingesundheit zu fördern und vor Krankheiten zu schützen. 

Eine der möglichen Mechanismen von Futterzusätzen ist die Modulation des Immunsystems. Hypothetisch interagieren SCFP durch präbiotische Mechanismen mit der mikrobiellen Gemeinschaft des Darm-Mikrobioms und beeinflussen damit indirekt das Immunsystem oder sie wirken durch postbiotische Effekte direkt auf residente Darmepithel- und Immunzellen sowie nach Resorption auf Immunzellen in der Peripherie...

To the doctoral thesis