I was wondering if feeding whiskey grains to horses had any benefits. I feed a mix of oats, corn, and roasted soybeans, and I was thinking of replacing some of the soy with whiskey grains.
Yes, distillers dried grains (whiskey grains) are a decent protein source for horses, and they contain a bit of fiber and fat as well. Kentucky Equine Research (KER) performed a study on distillers dried grains in the 1990s. Researchers found the feedstuff was accepted by the horses up to about 20% of the grain ration.
With this in mind, there are differences between distillers dried grains (DDG) and roasted soybean meal (SB), including (1) fat content (DDG, 10%; SB, 19%), (2) protein content (DDG, 30%; SB, 43%), (3) lysine content (DDG, 0.7%; SB, 2.5%), and (4) fiber content (DDG, 39%; SB, 22%). If you are feeding the mix to young growing horses, the difference in lysine would be significant.
There should be no problem with adding some distillers dried grains to the mix as long as you are only replacing a portion of the soy. By keeping soy in the mix, you maintain some high-quality protein that includes lysine.
Consult with a qualified nutritionist to be sure your home-mixed concentrate is providing your horse with all essential nutrients.