Make-up of gut bacteria in Thoroughbreds affected by intense exercise, study finds

Horses racing at the Partynice track in Poland.
Horses racing at the Partynice track in Poland. Photo by anvisuals on / CC BY

Intense exercise affects the make-up of gut bacteria in Thoroughbred racehorses, researchers have found.

Scientists with the Wrocław University of Environmental and Life Sciences in Poland found that intense exercise significantly influenced the abundance of Firmicutes and Bacteroidetes groups.

The study involved 17 healthy three-year-old Thoroughbred racehorses trained at Partynice Race Course in Poland. Their daily training regime involved trotting and cantering.

All were fed the same forage.

The exercise test used in the study was participation in a 1900-metre race at the course.

Fecal samples were collected for analysis from each horse before the race, and 48 hours after, for comparison.

None of the horses had undertaken a race or high-speed training session for two weeks before the race at the center of the study.

“There was a significant increase in the level of both groups compared to the state before the exercise,” Wanda Górniak and her colleagues reported in the journal Animals.

The study team suggests the changes may be related to changes in autonomic tone and increased sympathetic drive arising from the body’s response to exercise.

During exercise, a decrease in oxygenation of the intestinal mucosa is known to occur, which could affect the growth of bacteria in the digestive system of the tested horses.

“It should also be taken into account that the gastrointestinal microbiome acts as a specific immune system,” the authors noted.

The significant increase in the level of the studied phyla could be the result of the response of the digestive system microbiome to the intense effort of the exercise.

“The overall increase in the level of examined bacterial phyla may suggest that the physical effort stimulated the bacteria to proliferate, probably in order to increase the metabolism of nutrients, but further research on this issue is needed.”

Górniak and her colleagues said the results suggested there were differences in the horses’ individual responses to exercise.

“Despite the similarities in the level of the studied phyla, the individuals differed in their proportions,” they noted.

“However, due to the small amount of research carried out on horses, further analysis of the effects of both the individual and the effort on the gastrointestinal microbiome should be undertaken in the future, as the individual microbiological composition may also influence the horse’s response to physical effort.”

The authors said the changes found in the abundance of Firmicutes and Bacteroidetes groups may allow for a better adaptation of diet and maintenance conditions among Thoroughbreds, as well as improving the intensity and quantity of training for racehorses in the future.

“Moreover, the results suggest differences in the horses’ individual responses to exercise, which may suggest a more individual approach to the animal in the future, in order to improve its health status and ability to adapt to exercise.”

The study team comprised Górniak, Paulina Cholewińska, Natalia Szeligowska, Magdalena Wołoszyńska, Maria Soroko and Katarzyna Czyż, all with the Wrocław University of Environmental and Life Sciences.

Górniak, W.; Cholewińska, P.; Szeligowska, N.; Wołoszyńska, M.; Soroko, M.; Czyż, K. Effect of Intense Exercise on the Level of Bacteroidetes and Firmicutes Phyla in the Digestive System of Thoroughbred Racehorses. Animals 2021, 11, 290.

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

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