Effect of oral supplementation of probiotic strains of Lactobacillus rhamnosus and Enterococcus faecium on the composition of the faecal microbiota of foals

Abstract

Effects of probiotics on the intestinal microbiota of foals are yet insufficiently studied. The aim of this study was to investigate whether supplementation of Lactobacillus rhamnosus (DSM 7133) and Enterococcus faecium (DSM 7134) influences the bacterial composition of the faecal microbiota of foals. A total of 34 newborn foals were randomly assigned to the placebo group (PG, n = 16) and the treatment group (TG, n = 18). From day 1 to day 14 of life, foals orally received 3 ml of either a probiotic preparation (1.05 × 109 CFU E. faecium and 4.50 × 108 CFU L. rhamnosus) or placebo (carrier) once a day. Faeces were collected directly from the rectum immediately after birth (meconium) and at day 14 and day 56 of life. Samples of 12 foals per group were selected for microbiological analysis. DNA was extracted and used for polymerase chain reaction–denaturing gradient gel electrophoresis (PCR‐DGGE) and quantitative PCR. No DNA or amplicons were obtained from meconium. There were no differences in richness of bands and Shannon index of diversity regarding the Clostridium cluster XIVa between groups. Cluster analysis and principal coordinate analysis of DGGE data showed a clear effect of age. Band‐based similarity of bacterial clusters (Dice coefficient) decreased from day 14 to day 56 of life (p < 0.001) in PG foals only resulting in lower similarity in PG versus TG foals when 2 month old (p < 0.01). Five of thirty re‐amplified bands were identified on species level. Others were assigned either to family (mainly Lachnospiraceae) or genus level (Akkermansia). The bands related to Akkermansia muciniphila or Akkermansia spp. appeared almost in all DGGE profiles. Two‐week supplementation of the probiotic preparation to foals had no significant impact on the composition of the faecal microbiota but it appears to have prevented the reduction of bacterial similarity between 2 and 8 weeks of age observed in not treated foals.

Gut Microbiota Manipulation in Foals—Naturopathic Diarrhea Management, or Unsubstantiated Folly?

“…Numerous factors complicate attempts to map and manipulate the equine GIT microbiota. First, microbial populations and concentrations vary throughout the gastrointestinal tract [ 22 , 26 , 27 ], but for convenience reasons, studies generally rely on fecal samples, which reflect the microbial composition of only the right dorsal colon [ 22 ]. Microbial variation is also seen with age, body condition, sex, reproductive activity, breed, nutrition and management [ 5 , 6 ], general activity and stress level [ 8 ]; medications such as NSAIDs, antibiotics, antihelmintics and anesthetics [ 5 , 6 ]; and with exposure to foreign compounds like xenobiotics, polyketides and terpenoids found in the environment [ 28 ].…”

“…In addition to the desirability of reduced antimicrobial use, interest in prophylactic and therapeutic manipulation of gut microbiota has been driven by successful stabilization of favorable intestinal microbiota in other species [ 22 ] and a perceived high safety index [ 12 ]. The ease of oral pro- and prebiotic administration further adds to their appeal [ 56 ], and while FMT is a more involved procedure, it is still minimally invasive and requires only basic equipment.…”

“…The ease of oral pro- and prebiotic administration further adds to their appeal [ 56 ], and while FMT is a more involved procedure, it is still minimally invasive and requires only basic equipment. However, while adverse effects of probiotics are rare in all species, their impact on the microbiota of both adult horses and young foals is poorly understood, and negative outcomes have been reported in foals [ 9 , 22 , 23 ].…”

“…On the one hand, yeasts targeting the hindgut have been shown to improve digestion and assimilation of feed, and perhaps as a consequence, to improve growth performance [ 50 , 59 ]. In the EU, several products containing the yeast Saccharomyces cerevisiae are approved for use in horses as “digestive enhancers” or “gut flora stabilisers” [ 6 , 22 ]. S. cerevisiae has been shown to improve colonic digestion of acid and neutral detergent fiber in horses [ 50 , 59 ].…”

“…Finally, poor regulation and quality control of microbial supplements [ 10 , 15 , 16 ], demonstration of mobile antibiotic resistance genes [ 17 , 18 , 19 , 20 , 21 ] and toxin production [ 18 ] in probiotic strains, as well as documented adverse effects in foals [ 9 , 22 , 23 ], call into question the perceived safety of such treatments. Given the importance of the poorly understood foal microbiota, it is imperative not to interfere with its development arbitrarily, as uninformed intervention may have unintended consequences.…”