Green is good! We all love the look of our lush spring pastures, and our horses certainly love to graze them. But unfortunately, that tender grass poses some unique risks to equine health.

Spring grass grows rapidly, containing a large proportion (up to 80% or more) of water. This grass is generally soft and easy to chew because the amount of indigestible fiber is less than in mature grass. There is so much liquid in new spring grass that it contains lower proportions of all the other components—fiber, vitamins, minerals, protein, starch—compared to mature grass. This means that while a horse may ingest less starch per mouthful of spring grass (compared to summer or fall), because he finds it so tasty, he’s likely to eat more of it—and that’s where the trouble starts.

Virtually all horses are subject to some digestive upsets associated with lush spring pasture. The content of highly fermentable carbohydrates in lush pasture can be overwhelming to the digestive system. For overweight horses and ponies with insulin resistance and associated high levels of circulating pro-inflammatory agents produced by fat (equine metabolic syndrome), as well as those with known metabolic problems such as Cushing’s disease, grazing on lush pasture increases the risk of laminitis, colic and other health problems.

However, there are things you can do to reduce the potential problems associated with spring turnout and help your horse’s digestive system handle the spring grass that he so loves to graze:

1. Continue to offer hay even when the grass is growing well. New grass contains a lot of water and little fiber, and horses may crave the fiber found in hay.
2. Introduce your horse to lush spring grass gradually. To allow the digestive system to adapt, begin with short periods of grazing on lush grass and gradually increase time on pasture.
3. Monitor your horse for signs of laminitis and other problems. Check frequently (several times a day) for signs such as warm hooves or walking as though his feet may be painful. Horses that have been grazing through the winter and early spring are at somewhat less risk than horses that have been confined to stalls and are suddenly turned out into lush fields. If grazing horses show signs of any of these problems or seem uncomfortable, remove them from the pasture and call a veterinarian.
4. Use a grazing muzzle to restrict intake, and consider the use of a hindgut buffering product to neutralize lactic acid.

Hindgut problems can get serious. Overconsumption of high-starch concentrates or rich pasture grasses can make it impossible for the stomach and small intestine to sufficiently digest and absorb all that starch. When that happens, some of this starch moves into the hindgut (the cecum, large colon and small colon, where the breakdown of fiber normally occurs) without being adequately digested. This increases the production of lactic acid, causing a decrease in the pH. “Maintaining a good pH balance is crucial to a healthy digestive system and the microbiota that supports that system,” confirms Kathleen Crandell, Ph.D., equine nutritionist for Kentucky Equine Research. “When excessive amounts of starch or sugar end up in the hindgut of the horse, it will upset the normal pH, causing acidosis and affecting the health of the fiber-loving microbiota.”

As a result, your horse may appear “off his feed” or even colicky due to an inflamed and irritated intestinal lining. In the long term, he may experience a detrimental reduction of feed efficiency that could translate to poor performance. “To remedy a situation like this, a product that can help to normalize the pH is extremely helpful,” Crandell continues. “This is where something like a hindgut buffer would come in. Bicarbonate is an excellent acid buffer, but it needs to have a protective coating that will slow its release into the environment for it to be useful in the hindgut.”

So when you horse starts going for the green, make sure he stays as healthy as he is happy.