Safely Transitioning Your Horse's Diet

Whenever you decide to change your horse’s feed, whether it be forage (hay or pasture) or concentrate (grain), it is always recommended that you change their diet slowly. A sudden change in diet for a horse has been shown to be a leading cause of colic and laminitis.

What Researchers Say?

It is recommended that any change in a horse’s diet should be gradually introduced over a period of 2 to 4 weeks. Some may suggest a shorter period to transition your horse. However, the research we do have on the topic advises taking a longer period to ensure a safe transition to the new diet. Data has shown that a sudden change in the type or quality of hay fed to a horse within a 7-day period leads to a 20x greater chance of colic. This significantly decreased to a 2x greater chance of colic if the transition to the new hay took place over 3 to 4 weeks.

A similar pattern was observed when changing the type of concentrate (grain) fed to a horse. If the change happened within 7 days, there was a 13x greater chance of colic. Whereas, this significantly decreased to no increase in chances of colic when the transition to the new concentrate took place over 3 to 4 weeks. Therefore, when changing your horse to a new diet, a simple 3-week plan will suffice. For example, say an owner wants to change the hay they are feeding their horse. The feeding plan would look something like this:

Using this example, the owner would be feeding the horse 100% of the new hay by Week 4. It is important to remember to mix the hays together as horses can be picky eaters. If they were just left with two piles of hay, the horse may just eat one pile and ignore the other. This example could also be used for any new concentrate or grain being fed.

A slow transition to any new pasture would also be recommended. This would be especially true of a horse that has been consistently fed hay and is now being introduced to a pasture. It is generally recommended when starting a horse on pasture to allow them to graze for only 15 minutes. Then each day add 15 more minutes of grazing time until the horse is grazing for 4 to 5 hours. After that, the horse should be able to safely remain on the pasture for any duration. Read more about introducing your horse to pasture here.

The reason a slow transition with a new diet is so important is because the horse’s digestive system needs to adapt to any new feed. This is especially true of the microbes in the hindgut of your horse. A change in the type and density of certain nutrients (carbohydrate, fat, protein) alters the microbial population in the hindgut of the horse. Thus, a transition over many days and weeks gives the microbe population time to adjust to the new source of nutrients.

Finally, it has also been suggested that feeding a prebiotic and probiotic helps lessen the chance of digestive upset in a horse transitioning to a new feed. Consider Equi-Ferm XL®, which is a microencapsulated (protected) yeast that acts as a pre- and probiotic in the horse’s digestive tract. The microencapsulation helps the pre- and probiotics reach the hind gut, where they help support the growth of beneficial bacteria.


In summary, transitioning your horse to any new type of feedstuff (hay or feed) should be done so slowly. The three-week plan detailed above is easy to remember and will ensure your horse’s digestive tract remains healthy and optimized!

Article By: Chris Mortensen, Ph.D.
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