Guinness is part of an equine "breakfast of champions" for Tapit, a horse competing in today's Kentucky Derby. His trainer feeds Tapit three eggs and a pint of Guinness for breakfast each day. Tapit's trainer Michael Dickinson explains in the SportsTicker article:
"Guinness is made with the best malt and barley. It both whets his appetite and provides nutrients. I'm just trying to make life better for the horses and repay them for what they've given to me. They don't do this for the cups or the millions of dollars, they do it because they love it.