As you pour your horse’s grain into his feed tub, you might assume he doesn’t care—or even notice— how his meal looks, but research from the University of Minnesota sug- gests otherwise.
The study focused on the color of oat hulls, which range from white or yellow to tan and even black. The color has no effect on the quality of oats but, historically, feed companies have assumed that horse owners prefer those with white hulls. As a result, white-hulled oats are the most commonly planted for use in horse feeds.
To determine whether horses have a preference for particular oat colors, the Minnesota researchers used six mature horses who had not been fed oats before. In separate trials, the horses were repeatedly given the choice of eating either white or yellow oats from identical feed pans. For the first trial, researchers watched the horses eat a half pound of oats of each color, recording their pan choice every 15 seconds until all of the oats were consumed. That trial was repeated on 20 non-consecutive days.
In the second trial, the horses were presented with several pounds of oats of each color and allowed to eat for five minutes. Not all of the oats could be consumed in so short a time, and what was left was removed and weighed. This trial was repeated on 24 nonconsecutive days.
Data from the first trial indicated that horses had no color preferences—they consumed all of the oats they received. But the majority of horses in the second trial consumed more yellow oats than white oats in the five-minute period, suggesting they preferred yellow oats. The researchers note that although equine and human color perceptions are quite different, a horse’s vision does allow for differentiation between yellow and white. They also note that other factors, like aroma, could influence the equine preference for yellow oats.
Interestingly, the same researchers surveyed 801 horse owners about oat-color preferences and found none. The owners indicated that the quality they considered most important was cleanliness, while listing color and weight as least important. Researchers say this suggests that other market forces may be driving the perception that white oats are preferable.—Gulsah Kaya Karasu, DVM