Distiller's grains are like a special treat that cows get when people make alcohol. You know how mommy or daddy might enjoy a glass of wine or a beer? Well, the grown-ups use a special machine to make it, and when they are done, they have some leftover things that they don't need to make the alcohol taste good. These leftover things are called distiller's grains, and they make the cows really happy.
Distiller's grains are made from corn, which is ground up into tiny pieces. Then, the corn is mixed with water and special yeast that helps turn the sugar into alcohol. The yeast gets really hungry and eats all the sugar, and poops out alcohol. That's why it's a good idea for grown-ups to be careful when they drink alcohol, because it's like the yeast poop makes our brains feel funny.
Now, once the grown-ups have gotten all the alcohol they need for their drinks, they have some leftover wet grains. These grains look a bit like oatmeal, but they smell kind of like beer. So, instead of throwing them away, they give them to the cows to eat! The cows love it because it's like dessert for them. It's full of protein and nutrients that make them big and strong. And that's how cows get to enjoy a little bit of what their human friends like too!