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Large Intestinal Biome Established Early in a Horse's LifeBy Kentucky Equine Research Staff · January 20, 2016

The bacteria, fungi, and parasites that reside in the equine large intestine—commonly referred to as the horse’s biome or microbiota—play a vital role in health and disease. For example, sudden changes in the biome can cause colitis and laminitis. Although the importance of the biome is widely appreciated, experts suggest that our knowledge of how this complex ecosystem develops in foals remains unclear.

“This information is important because the biome in a newborn foal is thought to facilitate development of the immune system, establish the structure of the lining of the intestine, and assist in the foal’s ability to harvest energy from food,” explained Peter Huntington, B.V.Sc., M.A.C.V.Sc., director of nutrition at Kentucky Equine Research (Australia).

To obtain more information on the “pioneer” intestinal bacteria and the development of the biome in foals, a group of Canadian researchers* recruited 11 pregnant mares and collected fecal samples from the foals starting within 24 hours of birth and ending at roughly 270 days of age. Samples were analyzed using state-of-the art DNA technology.

Despite being born from a sterile uterine environment, foals had a “rich and diverse” bacterial community within 24 hours of being born. These microorganisms were thought to primarily come from the mare and the foaling environment. Biomes developed in the foals over the next 60 days of their lives, at which point the biomes were similar to their dams’ microbiota. The bacterial species identified at that point were thought to be the true intestinal colonizers, as the foal biomes tended to remain stable thereafter.

“The researchers also suggested that colostrum could impact the development of the foal biome,” noted Huntington. Thus, colostrum quality beyond IgG level could potentially impact intestinal health in foals.

That same group of researchers also looked at the impact of a probiotic on the development of the biome in foals. Although Lactobacillus spp. were enriched in foal feces at the end of the study period (6 weeks), the scientists indicated that the studied probiotic had a limited ability to help prevent diarrhea in foals. They did, however, suggest that higher doses could be studied, and that the fungi, viruses, and disease-causing organisms in foal biomes should be examined in supplemented animals. Further, probiotic products with ingredients other than Lactobacillus or Bifidobaterium spp., such as Saccharomyces cerevisiae, might ultimately prove beneficial.

*Costa, M.C., H.R. Stämpfli, E. Allen-Vercoe, et al. Development of the faecal microbiota in foals. Equine Veterinary Journal. In press.

**Schoster, A., L. Guardabassi, H.R. Staempfli, et al. The longitudinal effect of a multi-strain probiotic on the intestinal bacterial microbiota of neonatal foals. Equine Veterinary Journal. In press.