Horses fed a diet of 100% forage have greater bacterial stability and fewer "bad" fecal bacteria, than horses that are fed concentrates as well as forage. This recent research finding provides a further opportunity for the equine industry to develop feeding strategies that support equine health and welfare.

"Diets rich in readily fermentable carbohydrates, fed traditionally to meet the increased energy requirements of the performance horse, are associated with a number of gastrointestinal disorders that involve disturbances in the intestinal microbiota," wrote the research team, led by Professor Jan Erik Lindberg from the Department of Animal Science at the Swedish University of Agricultural Science.

In this preliminary study, researchers examined the impact of feeding a high-energy forage-only diet or a more traditional forage-concentrate diet on fecal microorganisms.

Lindberg and colleagues fed six mature Standardbred geldings in training either the forage-only or the forage-concentrate diets for 29 days. They extracted and analyzed bacterial DNA four times during the study period from the horses dung, measuring fecal pH and culturing bacteria on the last day.

One diet, called F, comprised early cut timothy/meadow fescue haylage, while the other, named diet C, comprised a late-cut timothy/meadow fescue (50% of dry matter) and feed concentrate (35.8 per cent starch, 50 per cent dry matter), comprising 82 per cent oats, 14 per cent soy bean meal, 2.7 per cent wheat bran and 1.4 per cent sugar.

Both diets were supplemented with daily vitamins, minerals and salt. Ground chalk was also added to the concentrate diet.

Diet F resulted in promoting stable gut bacteria.

The researchers stated that "Diet F resulted in a microbial composition that was more stable between sampling periods" The samples also had lower lower counts of undesirable gut bacteria, specifically members of the Streptococcus bovis/equinus complex.

It was noted by the researchers that Lactobacillus ruminis was present in all horses on diet C, but not in horses on diet F. Diet C also resulted in the increase in members of the Clostridial family.

The gut of horses is adapted to the continuous grazing of a fibre-rich diet, they said.

"Unfortunately, overload of readily fermentable carbohydrates results in the onset of a number of important equine diseases, including colic and laminitis."

The findings of this research provide an opportunity to develop feeding strategies that promote and maintain equine health and welfare.

The study, conducted by a group of researchers from the Swedish University of Agricultural Science, will be published in an upcoming edition of the Equine Veterinary Journal.  The abstract is available by clicking on the link below:

"Changes in faecal bacteria associated with concentrate and forage-only diets fed to horses in training".