Prebiotics may do more harm than good according to a recent
study in Germany.
Prebiotics are often added to horse feed in order to
stabilise the horse’s intestinal flora and promote good digestive health. They
are indigestible fibres that can stimulate the growth and activity of certain
beneficial bacteria in the large intestine.
However, researchers at Martin Luther University
Halle-Wittenberg (MLU) and the University of Veterinary Medicine Hannover
(TiHo) found that prebiotics only have a limited stabilising effect on the
intestinal flora of horses. Before they
can reach the intestines, commercially available supplements partially break
down in the animals' stomachs, which can lead to inflammation of the stomach
lining.
The team therefore suggests preparing prebiotic food
supplements so that they don't take effect until they reach the large
intestine. The study appeared recently in the journal "PLOS ONE".
"Horses have a relatively small, non-diverse core
microbiome and are therefore very susceptible to digestive disorders,"
explains Professor Annette Zeyner, head of the animal nutrition group at MLU.
However, according to the scientist, insufficient research has been conducted
on whether the use of prebiotics actually does produce the desired effects. Her
research group explored this question in partnership with Professor Gerhard
Breves’ lab from TiHo.
For the study, the team investigated the effect of feeding
Jerusalem artichoke meal (JAM) to horses. Jerusalem artichoke is often used as
a prebiotic for horses and contains high amounts of certain carbohydrates;
fructo-oligosaccharides and inulin.
In addition to their normal feed, six animals received JAM.
Another six horses received a placebo with their normal feed. The researchers
then analysed the balance of bacteria in the digestive tract of the animals of
both groups.
They found that the prebiotics were already being fermented
in the stomach by the microorganisms naturally living there - i.e. they were
taking effect much too early. "The fermentation process leads to the
formation of organic acids that - unlike in the large intestine - can damage
the mucous membrane of the horse’s stomach," says Maren Glatter, a member
of Zeyner’s group and lead author of the study.
However, the bacterial diversity of the entire digestive
tract did increase, which probably also produces the desired protective effect.
"Still, the prebiotics are probably more harmful than beneficial when used
in their present form," Zeyner surmises. Instead, the substances must be
treated so that they arrive in the large intestine in one dose in order to have
a positive effect on the intestinal bacteria living there without stimulating
overactivity.
For more details, see:
Modification
of the equine gastrointestinal microbiota by Jerusalem artichoke meal
supplementation.
Glatter M,
Borewicz K, van den Bogert B, Wensch-Dorendorf M, Bochnia M, Greef JM, Bachmann,
H. Smidt, G. Breves, A. Zeyner.
PLoS ONE (2019)
14(8): e0220553.
