21/04/2020
What is the best hay for horses?
Interestingly, horses are designed for a much more fibrous diet than cows! As far as we know, no animal is actually able to break down the fibers of plants to access the nutrients. That’s why herbivores work together with microbes that get a cozy home in the digestive system and in return “crack” the cell walls of ingested plants.
While cows and other ruminants house those microbes in the multi-chambered stomach and chew the food again after the initial fermentation process, horses are hindgut fermenters (or “perissodactyls” if you like five-dollar-words). This means that they transport the food all the way through the stomach and small intestines to the colon and cecum where it gets stored and fermented, which can take one to two days.
Most of the glucose, fat, and protein absorption takes place in the small intestines, between the stomach and the large intestines. Although the cell walls are not yet broken up at this point, a decent amount of those nutrients can be directly absorbed with the help of bacteria and enzymes. Horses have very strong grinding teeth that can do quite a bit of preparatory work to break up the food.
At first glance, ruminants seem to have an advantage, because the cell walls are broken up and more nutrients are released from the food before it moves to the small intestines. The problem is, that the fermenting microbes also have a taste for protein and glucose. If a cow has a diet with too much fiber, the stomach microbes use up more of the protein and glucose, so there’s not enough left for direct absorption.
Horses can compensate for high fiber content by simply eating more. They quickly absorb the freely available nutrients before the fermentation breaks up the cell walls and squeezes out as much good stuff as possible. If the food has low energy content, horses just ingest more of it and put it through the system faster. This keeps the digestive system moving smoothly, so lots of fiber is healthy for horses!
In a natural habitat, equids would select the stemmy, coarse forage while cows and other ruminants gulp down the green, leafy stuff. To accommodate the big meat and dairy market, most modern grasses in the fields are designed for cattle. This means that most hay is actually too nutritious for idle horses and easy keepers.
Let’s start with healthy mature horses at maintenance: try to find good quality hay that is rather stemmy – and then feed a lot of it, preferably free choice! This way the horses can eat all day long and get the fiber that their gut needs, without receiving excess energy. During the drying process, the hay loses some vitamins, especially vitamin A and E. If no fresh forage is available, you should compensate for that with a good vitamin / mineral supplement.
Now look at the horses’ additional needs and increase energy only as needed. Try to keep your horses on the kind of hay that they can eat all day. Ideally they should be able to get most of the energy and nutrients from hay or grass and concentrates should only be supplemental.
A short fast before a race might be helpful, but generally horses do best if they can eat 24/7. You have “air ferns”? Consider a low energy hay rather than small portions of rich hay and long fasting periods in between. Your horses are hard keepers or hard workers? Increase the energy content of the hay first before adding mountains of grain.
No two horses are alike and there is no “one size fits all” solution. But basing your horses’ diet on fiber and forage will keep their gut sound, their mind sane and your vet bills low.