Hoof Nutrition Intelligence is a twice-a-month web segment that is designed to add to the education of footcare professionals when it comes to effectively feeding the hoof. The goal of this web-exclusive feature is to zero in on specific areas of hoof nutrition and avoid broad-based articles that simply look at the overall equine feeding situation.
Below you will find the latest question and answer installment that you can share with your footcare clients.
Q: What impact will early spring grazing of lush forages have on the chances for my horses getting laminitis or colic?
By Kentucky Equine Research staffers
A: Horse owners frequently use the word “lush” to describe the state of pasture as it begins to grow rapidly in the spring. Lush pasture can be defined as a grazing area with plenty of abundant green forage that tempts horses to graze enthusiastically for hours on end.
Lush new spring grass, mature summer grass and dried autumn grass contain the same basic ingredients — water, vitamins, minerals, protein, starch and structural fiber among other things. Yet the proportions of these ingredients are far different depending on season.
Spring grass grows very 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 is found in mature grass.
Because there is so much liquid in new spring grass, the other components are found in lower proportions compared to mature grass, so the horse gets less starch per mouthful of grass than when grazing in the summer.
However, because this soft grass is so palatable, horses tend to ingest a larger overall volume of forage, so their intake of all nutrients may actually be fairly similar in spring, summer and early fall.
Temperatures at night are critical in determining the sugar content of the grass blades. If the temperature is not above 40 degrees F at night, the plant will not grow and sugars remain in the leaves in high concentrations. Research has shown that under certain climate conditions and at some growth stages, fructans may reach very high concentrations (as much as 50% of dry matter).
The unique chemical structure of fructans prevents breakdown in the stomach and small intestine. For this reason, these easily fermented sugars pass into the hindgut, a situation that leads to rapid production of lactic acid and an accumulation in the hindgut. This accumulation of lactic acid is a direct cause of colic and laminitis in pastured horses.
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. Horses and ponies that are overweight with insulin resistance and associated high levels of circulating pro-inflammatory agents produced by fat (equine metabolic syndrome) are particularly susceptible to pastures with high fructan content. However, many horses are able to handle some amount of pasture turnout if their digestive tracts are allowed time to adapt gradually to the dietary change and if a hindgut buffer is used to help neutralize lactic acid.
How can horse owners minimize the health challenges associated with lush pasture?
1 Continue to offer hay even though the grass is growing well. Since new grass contains a lot of water and little fiber, horses may crave the fiber found in hay.
2 To allow the digestive system to adapt to lush grass, begin with short periods of grazing and gradually increase time on pasture.
3 Check several times a day for signs such as warm hooves or horses walking as though their 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 stalled and are suddenly turned out into lush fields.
4 Consider using a grazing muzzle to restrict intake and consider the use of a hindgut buffer to neutralize the lactic acid.
5 Overweight horses, horses with known metabolic problems such as Cushing’s disease and several breeds of ponies may be at increased risk. However, any horse may develop problems after grazing lush pasture.
6 Spring grass is a known danger, but stressed grasses may store large quantities of fructans during the other seasons due to drought, overgrazing, temperature fluctuations and other conditions. For susceptible horses, there is no safe time to allow unlimited pasture access.
7 If grazing horses show signs of problems (colic, warm hooves, reluctance to move because of hoof pain), remove them from the pasture and call a veterinarian.
Kentucky Equine Research is a nutrition consulting company located in Versailles, Ky.
Click here to read part 1 of the Sept. 5, 2019 installment of Hoof Nutrition Intelligence: Is my farrier correct when he asks me to stop feeding bran since one of my mares has major hoof problems?
Click here to read more installments of Hoof Nutrition Intelligence.
Hoof Nutrition Intelligence is brought to you by W.F. Young Co. (Absorbine). 
Like many significant achievements, Absorbine® grew out of humble beginnings—and through the tenacity of someone willing to question the status quo. In this case, it was a young woman in late 19th-century Massachusetts: Mary Ida Young. Her husband, Wilbur Fenelon Young, was an enterprising piano deliveryman who relied on the couple’s team of horses to make deliveries throughout the Northeast. Inspired by Mary Ida and Wilbur’s vision, Absorbine® has continued to add innovative products throughout the years — products used every day by horse owners around the world. Which is why, since 1892, we’ve been The Horse World’s Most Trusted Name®.