After a long winter, we can finally feel like spring is in the air, and with it, new grass! While grass can be an important source of nutrition for your horse, too much of it can lead to obesity and potentially laminitis. This article will help you to understand how to best manage the introduction to spring pasture.
In most parts of Canada, year-round grazing is not an option, so owners will supplement the horse with hay. Eventually we reach a time where the horse could get most of their nutrition from grass and no hay is needed. During the transition, it is important to consider both the development of the plants themselves to establish a healthy pasture for the summer, and to keep in mind the needs and health of the horse as well.
For horses turned out 24 hours a day, 7 days a week, the transition from hay to grass may seem natural as the grass comes in. As soon as spring grasses peek above the soil, horses will turn their noses at their hay bales and dig in. However, it is important to try to prevent that a bit.
Protecting the Roots
The grass’s root system depends on a healthy above-ground portion of the plant to provide the plant’s food (from sunshine and carbon dioxide). And of course, we need healthy roots to develop to gather water and minerals such as nitrogen, which is required for any plant to produce protein. Therefore it is important to allow the grass to grow in a bit before grazing to allow for the plant to grow and for the roots to develop.
A photo from a Canadian research station showing the root growth of bunchgrass plants that were kept clipped at certain levels – representing the effects of overgrazing on root growth. (managingwholes.com)
During this early growth time, you might consider developing a rotational grazing system, where you can allow parts of your pasture to grow in a bit before it is trampled and eaten by your horses. A good rule of thumb is to allow the grass to grow until it is 6-8 inches before allowing it to be grazed. You can use a simple temporary fencing system to keep your horses in one section (a sacrifice area) with hay and water while the rest of the paddock develops. Then you can open up other areas of the pasture to let the horses graze, and when they graze down to about 3-4 inches (where the root system could be damaged by further grazing) you would close that section up and open up a new one, and so forth. This system will help you to establish a healthy pasture which will provide more nutrients for your horse, perhaps to a point where they wouldn’t need much additional hay and/or concentrates to meet their nutritional needs.
Fear the Fructans
From the horse’s perspective, pasture does an excellent job of providing protein, minerals and vitamins. Many horses can do very well with managed pasture, water and a salt or trace-mineral source (as salt and some trace minerals can be lacking in pasture). Pasture can also be a major source of calories, and in fact, most horses will consume enough grass in a 24-hr period to take in more calories than they actually need. Horses can gain weight; even though horses evolved to consume pasture grasses and not be overweight, they also had to walk many miles per day to get their grass and water, and the grasses available to them were not nice and lush.
Furthermore, pasture – particularly in the spring – can be very rich in sugar, starch and fructans. Both sugars and starch are digested to glucose, which is absorbed by the horse and metabolized to produce energy, or is stored as fat, but too much glucose in the system can also predispose a horse to metabolic problems. Fructans are a type of complex fibres that are not digested until they reach the hindgut (cecum and colon) but once there, they are fermented rapidly. This can produce excessive acids and gasses, causing a situation where the integrity of the gut becomes compromised and toxins may be absorbed into the bloodstream.
Fructans tend to be higher in the spring (and fall) because they are synthesized with bright, sunny days and accumulate over cool nights. Horses at pasture therefore may be getting a trifecta of danger – obesity, metabolic issues and fructans – all of which can predispose a horse to laminitis (a debilitating and often deadly hoof condition).
Setting Limits
Therefore, in addition to managing and rotating pastures to facilitate plant growth, you should also consider limiting the time a horse has at pasture, in particular during the spring. While some horses can live on 24/7 pasture and maintain a good body weight, most horses will overeat. Using a sacrifice area can limit the time (in terms of total hours per day) a horse has at pasture. You should consider turning your horse out early in the morning when sugars are lower because they’ve been used overnight by the plants, compared to later in the day when the sun has been helping to make more sugar. However, if it was a cool night, you might consider reducing the total time at pasture even further to limit fructan intake.
Introducing pasture to horses slowly can also facilitate the adaptation of the equine microbial system to the sugars and fructans, and decrease the risk of a sudden introduction of large amounts of these compounds.
For those lucky horses that live on pasture 24/7, don’t become overweight, and have enough land available so that plant growth is never limited or damaged, nature kind of does its own job as the grass comes in and the horses adapt to it. But for the majority horses, monitoring plant growth and intake is important to keep both the pasture and the horse healthy.