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Can an emergency change in feed be made safely?
- July 21, 2025
- ⎯ EQUUS
Question
When Hurricane Helene hit last year, we were due a shipment of feed, which was delayed for three weeks. We ran out entirely, but we were fortunate: Our neighbors use the same type of feed and were able to share. I know sudden changes in diet can trigger colic so I worry that in another crisis we might not be so lucky. In an emergency situation, how can you handle a sudden feed change? Or is it better to just let the horses eat only hay or grass until you can get their usual feed?
Answer
Unexpectedly ending up without your horse’s normal grain ration is certainly a dilemma. The best way to handle it will vary with the circumstances, but even without knowing your horse’s body weight, body condition score (BCS) or exercise level, I can give you some general advice.

Natural disasters and other emergencies can disrupt feed supplies. (Adobe Stock)
If your horse is an adequate body weight—with a BCS of 5 or above on the nine-point scale—then a few days to even a few weeks without grain will probably not be a problem. Here are the calculations that explain why: A 1,100-pound (500-kilogram) horse requires 16.4 Mcal of digestible energy (DE) for maintenance and between 20 and 23 Mcal DE for light to moderate exercise. Horses can easily consume 1.5 to 2 percent of their body weight in dry matter per day. This would equate to 16.5 to 22 pounds (7.5 to 10 kilograms) of dry matter, and if that is all forage with an average of 1.75Mcal/kg (0.8Mcal/pound) the total consumption of DE would be 13 to 17.5 Mcal DE.
This would satisfy the DE requirement for horses in maintenance. It would fall short 7 to 10 Mcal per day on the lower consumption level and only 3 to 6 Mcal per day short on the higher consumption level. A deficit of about 7 Mcal will result in 1 kilogram of weight loss (approximately 2.2 pounds). These expected deficits could result in about 1 kg (2.2 pounds) of weight loss per day, over a week would be about 15 pounds (7kg) and 45 pounds (21kg) over three weeks. In a 1,100-pound (500-kilogram) horse, this would be hardly noticeable in the first week and may only start to show after the three weeks with a loss of 45 pounds (21kg).
A benefit of a forage-only diet
Beyond weight loss, there isn’t too much concern with an abrupt change to a forage-only diet. A horse and his microbial gut population are much better able to handle a reduction of the grain component in a diet than an increase in grain or a change to a different type of grain.
When including grain
If you felt that you had to incorporate grain into your horse diet, and you did not have access to his usual ration, you could introduce a new product slowly over approximately seven days just as you would if you wanted to switch grain products. The typical recommendation is to mix old and new products over seven days. The recommendation would be 75:25 old to new product for 2 days, 50:50 old to new product for 2 days, 25:75 old to new product for two days and changing to 100 percent new product on day seven.
Without old product to use in this ratio, I would recommend you start with small amounts such as 25 percent of the old ration amount for two days, 50 percent of the old ration amount for two days, 75 percent of the old ration amount for two days and finally building to the old ration amount with the new product on day seven. This may result in a calorie deficit for the week but, as I have explained, the weight loss will not be significant over this adjustment period and would most likely not be noticeable.
Considerations
If the horse had a BCS of less than five (which would be considered thinner than ideal), or the horse is older and might have dental problems, then the amount of weight loss might be greater and more noticeable over three weeks. In this case, I would allow the horse access to as much forage as he could eat, while incorporating a new grain product as described. Research has shown that a loss or gain of approximately 100 pounds (45 kilograms) is needed to change body condition score by one point. Therefore, if your horse went from a BCS of four to a BSC of three, that would mean he lost body weight in excess of the amount expected in this example over three weeks.
Patty Graham-Thiers, MS, PhD
Emory & Henry University
Emory, Virginia
Our Expert
Patty Graham-Thiers, MS, PhD, heads the Equine Studies Program at Emory & Henry University. She received her Master’s degree from the University of Florida, Gainesville, and her doctorate from Virginia Polytechnic Institute in Blacksburg. She was a member of the committee that wrote Nutrient Requirements of Horses, 6th Edition (2007).