Livestock Update, January 2000
Larry A. Lawrence, Extension Animal Scientist, Horses, Virginia Tech
Breakthrough equine research at the Middleburg Agricultural Research and Extension Center has helped shed new light on an old problem. This year there seems to have been an increase in colics in horses on pasture.
Some of the colic may be attributable to excessive and variable "energy" coupled with low fiber content of pasture. Dramatic changes in the percentages of starch and rapidly fermentable carbohydrates can occur under the following conditions (all of which the Mid-Atlantic States have experienced in 1999): 1) early spring rains and moderate temperatures into early summer; 2) large amounts of rainfall after a period of drought; 3) significant fall rains and moderate temperatures.
This fall, forage production has been very high. Some of this is the result of conservation of nutrients this summer when pastures failed to grow because of drought. This high forage availability combined with the unique characteristic of fescue to increase starch and highly fermentable carbohydrate from 15 to 30% after a frost has created a management problem for horse owners with fescue pastures.
Horses that were not grazing fescue late summer and fall will find the fescue quite palatable and may over-consume the forage after a hard frost. The equine digestive system is not designed to handle excessive starch or highly fermentable carbohydrate.
What can you do to help manage the problem? Don't allow horses unlimited access to fescue after a frost. Treat the horse as if you were changing feeds and slowly readapt them to the pasture. Cut down grazing time. Fill the horse before turnout on a medium quality grass hay (no alfalfa or clover) to provide a better balance of carbohydrates. Make sure the horse always has free access to a good quality source of water. Be alert to the signs of colic including increased gas, signs of discomfort include rolling, looking back and biting or kicking at the horse's sides, failure to eat or drink, elevated heart rate, standing in a stretched position, unexplained excitement, anger or depression.
The MARE Center is currently working on a supplement for pasture that contains multiple sources of fibers to help stabilize the horse's digestive system.