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

Simple Summary

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.

Abstract

Feed supplements such as Saccharomyces cerevisiae fermentation products (SCFP) alter immune responses in horses. The purpose of this study was to analyze whether a prebiotic activity of the SCFP alters the gut microbiome in horses. Racehorses were fed either SCFP (Olimond BB, OLI, n = 6) or placebo pellets (PLA, n = 5) for 43 days. Fecal microbiota analysis was performed using 16S rRNA gene sequencing. The numbers and function of circulating immune cell subpopulations were analyzed by flow cytometry. SCFP supplementation resulted in non-consistent differences in fecal microbiota between the PLA and OLI during the feeding period. Rather, the individual animal had the highest impact on fecal microbiota composition. OLI and PLA horses displayed the same changes in numbers of blood leukocyte subpopulations over time. One day after a booster vaccination against equine influenza during the feeding period, the alpha diversity of fecal microbiota of PLA horses was significantly higher compared to OLI horses. This suggests that SCFP feeding altered the vaccination-induced spectrum of released mediators, potentially affecting gut microbiota. The overall non-consistent findings argue against a strong prebiotic effect of Olimond BB on the microbiota in racehorses. Fecal microbiota differences between the groups were also noticed outside the feeding period and, hence, are most likely not caused by the SCFP additive.

[Effects of oral manganese supplementation with different compounds on the manganese whole blood and serum concentrations of broodmares and their suckling foals]

OBJECTIVE

This study aimed to examine the effects of an oral supplementation on manganese (Mn) concentrations in the blood of lactating warm-blood broodmares. Furthermore, the potential relationship between Mn supply of the lactating mare and its suckling foal was investigated.

MATERIAL AND METHODS

During the 90-day trial, lactating mares were divided into 3 groups and daily received a daily dose of either a placebo (n = 11) or a Mn supplement of 560 mg Mn as Mn sulfate (n = 11) or Mn chelate (n = 11) in addition to the Mn intake from the basal ration (hay ad libitum, total mixed ration: Mn intake ~ 100 mg/kg dry matter). Blood samples were taken from the mares and their foals in 14-day intervals. The Mn determination in serum and whole blood as well as in the mare's milk was carried out by means of mass spectrometry with inductively coupled plasma. The Mn analysis in representative feed samples was performed by means of atomic absorption spectrometry. Data were assessed using the software IBM SPSS Statistics 27 (IBM Deutschland GmbH, Ehningen).

RESULTS

During the trial period, the mares showed Mn concentrations 10-fold higher in whole blood (median: 15.6 µg/l; 25-75 percentile: 12.8-18.5 µg/l) than in serum (median: 1.54 µg/l; 25-75 percentile: 1.20-1.90 µg/l). The foals had Mn whole-blood concentrations 16.4-fold higher (median: 21.3 µg/l; 25-75 percentile: 16.7-28.1 µg/l) compared to their serum (median: 1.50 µg/l; 25-75 percentile: 1.30-1.70 µg/l). The Mn whole-blood levels of the foals corresponded to 1.6-fold the Mn concentration of their dams. The milk contained a median Mn concentration of 0.012 mg/kg fresh matter. Mn supplementation had no effect on the Mn blood levels of mares and their foals.

CONCLUSION AND CLINICAL RELEVANCE

Blood Mn concentrations were not affected by the Mn supplementation. However, the Mn levels differed significantly between serum and whole blood. In addition, the Mn concentrations in whole blood of suckling foals were higher compared to their dams, although the Mn concentrations in the mare's milk were low regardless of Mn supplementation. Due to the low Mn content in milk, early Mn supply, preferably by forages, is necessary to ensure that the foals are supplied with Mn according to their requirement.

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

Saccharomyces cerevisiae (S. cerevisiae) fermentation products (SCFP) are used in animal husbandry as pre- and postbiotic feed supplements. A variety of immunomodulatory effects are noted in many species. The purpose of this study was to test the hypothesis that horses fed with SCFP containing feed additive Olimond BB display a modulated early immune response after influenza vaccination. Six horses received Olimond BB pellets (OLI) and five horses were fed placebo pellets (PLA) for 56 days. On day 40 all horses were vaccinated with a recombinant influenza A/equi-2 vaccine. At the day of vaccination, the groups did not differ in the composition of leukocyte subpopulations and reticulocytes. Twenty-four hours after vaccination total leukocyte counts and numbers of CD4+ T-cells significantly increased in both groups. In PLA horses, the numbers of neutrophil granulocytes significantly increased and numbers of CD8+ T-cells decreased, whereas the numbers of these cell types remained unchanged in OLI horses. Only OLI horses displayed a significant increase in reticulocyte percentages after vaccination. The numbers of lymphocytes, monocytes, CD21+ B-cells, and serum amyloid A levels remained unaffected in both groups after vaccination. Sixteen days after vaccination, PLA and OLI horses differed significantly in their enhanced ELISA IgG titres against Newmarket and Florida Clade 1 influenza strains. The observed differences after vaccination suggest that feed supplementation with Olimond BB leads to modulated early immune responses after influenza vaccination, which may also affect the memory responses after booster vaccination.