Fast Forage Switches Not Recommended for Horses

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By Jackie Bellamy-Zions

Do you know the first signs your horse’s digestive system is in danger? Diarrhea, upset stomach, or the worst scenario — colic — can all be caused by changing from one type of forage to another too quickly. Whether it is moving barns, moving to a new batch of hay from the supplier, or switching from a lush, moist, grassy paddock to a dry sandy sacrifice paddock and dry hay, the importance of switching forages slowly cannot be overstated. An adaptation period of 10 to 14 days to transition new feeds into your horse’s diet is recommended.

Forage makes up the largest portion of the horse’s diet and using an adaption period is of utmost importance when introducing a new forage source to your horse’s diet. A change in hay/pasture has been associated with the highest risk of colic (Hillyer et al., 2002).

Example of an adaptation period:

Days 1 to 3: 75 percent old hay and 25 percent new hay.

Days 4 to 6: 50 percent old hay and 50 percent new hay.

Days 7 to 10: 25 percent old hay and 75 percent new hay.

Educated horse owners take great care when introducing horses to spring grass in order to avoid health issues, but they are not always as judicious when pulling horses off grass in the late fall and early winter. “Switching from a grass to a legume hay, and also from a fresh grass pasture to a dried grass or mixed hay, it is beneficial to add a ‘yeast culture’ or a ‘prebiotic’ to their diet for 10 to 14 days while making the transition,” says highly experienced equine nutritionist, Don Kapper.

Understanding the inhabitants of the horse’s gut makes it easy to grasp the importance of making dietary changes slowly. The quantity and type of microbes living in the gut will be determined by the type of forage being eaten. It takes different microbes to ferment and break down grasses than it does legumes. Loose stools and digestive upset are common results from making a fast change in forage type, such as switching from a timothy grass hay to a legume hay like alfalfa. There will simply not be enough of the correct type of microbes available to help with fermentation and the horse’s health will suffer.

“Loose stools are a sure sign that the colon is not doing its job of reabsorbing water and forming the stools,” says Kapper. “That is why the prebiotics are recommended to help whenever the stools become soft or loose enough to cause diarrhea. Because we are dealing with the health of the microbes in the colon, a ‘treatment’ level should be administered for five additional days after the stools become normal. Prebiotics are a ‘food’ to help the microbes stay healthy, grow, and multiply, and are colon-specific as opposed to probiotics. The majority of the probiotics will not make it into the colon.”

Discuss your options with an equine nutritionist to help choose the right product for your horse.

Forage is the bulk of the horse’s diet. To keep your horse’s microbes happy, making changes to feed slowly is important, even more so for forage than grain mixtures.

Equine nutritionist Don Kapper (Professional Animal Scientist) is the author of the chapter on “Applied Nutrition” for the authoritative veterinary textbook: Equine Internal Medicine, 2nd edition and was a member of the Performance Electrolyte Research team at the University of Guelph. He is also a frequent guest speaker in Equine Guelph’s online Nutrition courses and online Gut Health and Colic Prevention course.

Reprinted with the kind permission of Equine Guelph.

Photo: Shutterstock/Alexia Khrischeva


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