What to make of lush green grass?
With all the rain over the past year the South Coast has a lot of lush green grass around.
What do we mean by lush pasture? Lush means to “grow vigorously”, so we refer to those green grazing areas with plenty of green forage as “lush pastures”.
Grass usually contains basic ingredients including water, vitamins, minerals, protein, sugars, starch and fibre. Lush spring grass grows rapidly and contains a large percentage of water, up to 80% or more. This means there’s a lower proportion of other things like sugars in spring grasses. However, this grass is soft and easy for horses to chew because the amount of indigestible fibre is much less compared to mature grass, making it more palatable. Horses tend to gorge themselves on fresh spring grass and ingest larger amounts of forage, this is when it becomes risky in terms of how much sugar and starch they are consuming, especially if they are already carrying a bit too much weight.
Fructans are a type of sugar that are produced by photosynthesis in daylight hours. When more sugar is made in the grass than what is used for growth, the sugars are then stored in the root, leaf base and leaf blade. Many cool-season grasses store more fructans in the base of the plant than in the leaves. It is for this reason that spring grass is a known danger, but there is a risk whenever there is a lot of rainfall and hence fast grass growth.
Most of the water-soluble carbohydrates found in grass are absorbed by the horse in the small intestine, however, fructan is not broken down in the stomach and small intestine and goes into the hindgut where it leads to rapid production of lactic acid which accumulates and can have negative consequences for your horse such as colic and laminitis.
All horses are subject to some digestive disturbance associated with lush pasture. This can range from loose manure from the high-water content to more severe disturbances associated with high fructans content, such a laminitis.
Many horses are able to handle some degree of pasture turnout if their digestive system is allowed to gradually adapt to the dietary change.
If your horse is not coping with the lush pasture and develops laminitis (short stepping, hot hooves, reluctant to pick up feet) take the horse off pasture until there is complete resolution of the acute laminitis episode and supplement a laminitis-approved diet by consulting your veterinarian or equine nutritionist. A gradual reintroduction to pasture may be considered if there are no underlying diseases, however caution should be taken if the grass is still lush.
Avoid putting horses out onto pastures that have not been managed by regular grazing or cutting, because mature stemmy grasses may contain fructans (in the stem). Do not allow horses to graze recently cut or mowed stubble, because fructan is stored mostly in the stem of the grass. Instead, you should wait 2 to 3 weeks until the grass has grown and used up most of the sugars for its growth. Restrict pasture turnout during the day (e.g. 1-3 hours) and turn animals out late at night (after 8pm, or early morning and remove them from the pasture by mid-morning). If this is not feasible, rotational grazing or temporary fencing to section off grazing areas may be utilised.