Make-up of equine gut bacteria altered by exercise, study shows

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A Mangalarga Marchador horses. Photo: No machine-readable author provided. Pbicalho assumed (based on copyright claims). CC BY-SA 2.5, via Wikimedia Commons
A Mangalarga Marchador horse. © Pbicalho assumed (based on copyright claims). CC BY-SA 2.5, via Wikimedia Commons

Exercised-related changes in the gut bacteria of horses early in training have been identified in a study in Brazil. 

Significant changes in the microbial balance in the gut− the microbiota − were noted in response to intense exercise in the Mangalarga Marchador fillies used in the study, with an apparent recovery towards baseline levels as their adaptation to exercise occurred.

“This suggests that while exercise may alter the microbiota, changes in exercise (as opposed to the amount of exercise) may be the most important factor,” Maria Luiza Mendes de Almeida and her colleagues reported in the open-access peer-reviewed journal PLOS ONE.

“The findings of this study suggest that exercise and a fitness program can potentially modify the intestinal microbiota communities of fillies during the early stages of conditioning.”

The authors noted that the relationship between intestinal microbiota and physical activity was in the early stages of scientific exploration.

The study is understood to be the first to employ an experimental model of controlled intensity exercise to evaluate changes in the bacterial population of fillies.

“Our results suggest that the exercise-training-gut microbiota relationship in athletic horses warrants further investigation,” they concluded.

The study team noted that recent studies performed in humans and rats showed that exercise can alter the make-up of intestinal bacteria.

“Athletic horses perform intense exercise regularly, but studies characterizing horse microbiome during aerobic conditioning programs are still limited.”

The researchers had set out to learn more about the effects of supplementing horses with chromium and the amino acid derivative and nutrient L-carnitine, each of which could have performance-enhancing abilities since they were possibly able to modify the metabolism of carbohydrates and lipids.

They set up an experiment involving 12 horses to assess the impact of acute exercise and aerobic conditioning, associated either with L-carnitine or chromium supplementation, on intestinal bacteria.

The horses, all in the early stages of fitness work, were divided into four groups. The control group received no exercise throughout while the second group underwent a treadmill exercise regime but received neither of the supplements. The third group was supplemented with L-carnitine and underwent the exercise regime, while the fourth group was given chelated chromium and undertook the same exercise program.

The horses underwent two exercise tests before and after a training program on a treadmill for 42 days at 70–80% of the lactate threshold intensity. Fecal samples were obtained before and 48 hours after acute exercise for molecular analysis to identify the bacteria present.

The results showed that, overall, the two most abundant phyla were Firmicutes (50.22%) followed by Verrucomicrobia (15.13%). The taxa with the highest relative abundances were unclassified Clostridiales (17.06%) and “5 genus incertae sedis” from the phylum Verrucomicrobia (12.98%).

There was a decrease in the phylum Chlamydiae and in the genus Mycobacterium after the second incremental exercise test.

“Intense exercise changed the community’s structure and aerobic conditioning was associated with changes in the composition and structure of the intestinal bacterial population of fillies,” they reported.

Comparisons within the group showed that chromium or L-carnitine induced only moderate changes in the fecal microbiota of fillies, but the microbiota did not differ from the control group which was exercised with no supplementation.

The impact of supplementation was questionable, they said. “A limited impact of L-carnitine and chromium was noted during evaluation; however, the highly limited statistical power of these pilot data must be considered.”

Despite this, significant differences were observed in a measure of the microbial population in terms of the presence or absence of members under what is known as the Jaccard index between both treatment groups and the control group.

“This suggests that these compounds might alter the microbiota directly or modify the response of the microbiota to exercise; however, care must be taken when interpreting these results given the lack of other demonstrable changes.”

The study team acknowledged some limitations in the study, such as the low number of animals used in each supplemented group. Additionally, significant changes were observed in the microbiota of the control group during the experiment, despite the adjustment period.

“Nevertheless, it is noteworthy that the diet provided to the exercise group was consistent over time, which allowed animals to be compared to themselves before versus after treatment, facilitating evaluation of the unique effects of exercise on the microbiota.

Almeida was joined in the study by Walter Heinz Feringer Júnior, Júlia Ribeiro Garcia Carvalho, Isadora Mestriner Rodrigues, Lilian Rezende Jordão, Mayara Gonçalves Fonseca, Adalgiza Souza Carneiro de Rezende, Antonio de Queiroz Neto, J. Scott Weese , Márcio Carvalho da Costa , Eliana Gertrudes de Macedo Lemos and Guilherme de Camargo Ferraz.

Almeida MLMd, Feringer WH Júnior, Carvalho JRG, Rodrigues IM, Jordão LR, Fonseca MG, et al. (2016) Intense Exercise and Aerobic Conditioning Associated with Chromium or L-Carnitine Supplementation Modified the Fecal Microbiota of Fillies. PLoS ONE 11(12): e0167108. doi:10.1371/journal.pone.0167108

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

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