Question

My gelding has come up slightly lame occasionally throughout this past summer. Though he has a history of acute laminitis 13 years ago, there have been no recent concerns with lameness until now, so I have been looking for possible causes. I noticed that the grain in the bottom of the bin had almost disintegrated to a powder. Because he gets so little grain--a 50-pound (22-kilogram) bag lasts four months--I usually keep it in the house, but this time I left it in the barn. I threw out the grain even though it didn't smell bad, though the color had become pale. Could this mean it was moldy? Because of the gelding's history of laminitis, I reduced his grain to 1/4 cup and have been giving him bute two times per day, as recommended by my vet. The grain was purchased sometime in May. Please let me know if the feed could have caused the lameness. What is the usual shelf life of grain if kept in a climate-controlled, airtight container compared to a grain bin in the barn during summer months?

Answer

There is a limited shelf life with commercial feeds, and the expiration date is not always the most accurate guide to when they are no longer usable. Most feed companies would expect a product to be safe to feed for up to two months from the date of manufacture, and it may be reasonable to expect it to be nutritious and safe for three months when kept in the correct environment.  Atmospheric moisture (humidity) is most detrimental to an open bag of feed, with temperature having the next most damaging effect. Once a feed is dumped into a bin, it is exposed to not only higher moisture and possibly heat, but also invasion by insects or rodents. From your description, the feed was probably beyond suitable for consumption if it was losing its color and shape.

With the very small feeding rate (less than 1 cup per day), however, even moldy feed should not have the effect you are seeing on his feet. Palatability decreases as feed deteriorates, and horses tend to refuse to eat moldy feed. The usual effects of mold consumption are colic rather than laminitis.  If the feed is stale but not moldy, it will have an unusual smell, much like the smell of stale crackers. If it is moldy, it will have a strong acrid smell, similar to moldy tack.

If you are concerned about the horse not eating the feed quickly enough, I would keep it indoors.  Are you feeding any type of vitamin and mineral supplement to your horse? Because he is getting an amount well below the recommended feeding rate, he will not be getting the balance of vitamins and minerals that might be expected. He may be better off with a ration balancer.–Dr. Kathleen Crandell