Scientists map bacterial gut changes in developing foals

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Researchers say the bacterial gut community of foals follows a predictable pattern early in life.
Researchers say the bacterial gut community of foals follows a predictable pattern early in life.

Researchers have charted the changes in bacteria that inhabit the gut of foals from birth to weaning, noting changes as the months progressed and aberrations that mark potentially serious problems such as diarrhea.

A healthy gastrointestinal tract with a properly established microbiota – community of microorganisms – is necessary for a foal to develop into a healthy weanling.

A foal grows from about 10% of its mature body weight at birth to as much as 50% of that weight by the time of weaning.

As they grow, synchronization occurs between the changes in dietary needs, changes in the type of food consumed and shifts in the gut microbiota to bacterial populations that can more efficiently digest the diet provided.

The importance of the microbiota on health is being realized because of the sudden increase of available information on gut microbiota composition and functions thanks to modern DNA analysis.

“The gut microbiota may even be seen as an organ system in the host, given the important roles it plays in processing ingested organic matter,” Ubaldo De La Torre and his colleagues at the University of California, Davis, reported in the open-access journal PLOS ONE.

“The health of the host, or in this case the foal, is dependent upon these microbes and can be impacted by perturbances to the microbiota such as those caused by infectious diseases or antibiotic treatment.”

The authors said studies have begun to understand which microbial populations comprise healthy and unhealthy gut microbiomes and how they may change once the foal no longer relies on the mare for food.

Since there are many risks to the well-being of a newborn foal’s gut health, developing methods to track and assess gut health would be useful.

The researchers hypothesized that differences in gut establishment by age and by diarrhea status would be detectable in analyses of the fecal microbiotas of foals from birth to weaning.

A foal grows from about 10% of its mature body weight at birth to as much as 50% of that weight by the time of weaning.
A foal grows from about 10% of its mature body weight at birth to as much as 50% of that weight by the time of weaning.

For the study, voluntarily voided fecal samples were collected from 37 sets of foals and mares at three different farm locations. Most were either thoroughbreds or quarter horses. The farms shared some things in common in the way they managed their horses, but also had differences.

Samples were collected from foals on five occasions, on days 1, 7, 28, 60, and at weaning.

Molecular-based technology was used to test the samples for bacterial DNA.

The results revealed an abundance of Proteobacteria, mainly of the Acinetobacter genus, in day-old foals compared to the other age groups.

Proteobacteria were still present in seven-day-old foals, but had lowered significantly by the 28th day.

From the age of seven days to the day of weaning, an abundance of Firmicutes followed by Bacteroidetes was observed throughout the samples. Two common microbial families – Lachnospiraceae and Ruminococcaceae – were seen in foals from day 7 until weaning, and in mares. These are necessary for the breakdown of complex carbohydrates, as required for a grass diet.

“We found that bacterial population compositions followed a pattern throughout the early life of the foal in an age-dependent manner,” the study team reported.

“As foals transitioned from milk consumption to a forage and grain diet, there were recognizable changes in fecal microbial compositions from initial populations predominant in the ability to metabolize milk to populations capable of utilizing fibrous plant material.

“We were also able to recognize differences in microbial populations amongst diarrheic foals as well as microbial population differences associated with differences in management styles between facilities.”

The researchers said they would focus future efforts on gauging the effects of less abundant bacterial populations identified in the study that could prove essential to gut health.

They said they also wanted to learn more about the associations between microbial population profiles and animal management practices, which could ultimately improve the health and growth of horses.

The study team comprised De La Torre, John Henderson, Kathleen Furtado, Madeleine Pedroja, O’Malley Elenamarie, Anthony Mora, Monica Pechanec, Elizabeth Maga and Michael Mienaltowski, all with the University of California, Davis.

De La Torre U, Henderson JD, Furtado KL, Pedroja M, Elenamarie O, Mora A, et al. (2019) Utilizing the fecal microbiota to understand foal gut transitions from birth to weaning. PLoS ONE 14(4): e0216211. https://doi.org/10.1371/journal.pone.0216211

The study, published under a Creative Commons License, can be read here

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