Spent grains are not nutritionally complete, so they are used as a supplement to regular feed. Animals fed spent grains will likely benefit from supplementary nitrogen and calcium.
For cattle, the University of Florida recommends 30 to 50 pounds (wet weight) spent grains per day, and 20 pounds (wet weight) per day maximum for calves. This corresponds to 8 to 13 pounds per day dry weight for cattle and 2 to 5 pounds dry weight per day for calves. A study in which various proportions of spent grains to regular feed were compared found that 15 to 30 percent of the diet being spent grains led to the fastest weight gain. In chickens, supplementing their regular feed with 10 to 20 percent dried spent grains was found to be the most effective.
Spent grains are the major waste in the brewing process. With feed being the major cost associated with raising cattle, utilizing spent grains – turning beer ingredients into beef – proves beneficial to both brewer and farmer. With some additional supplementing, spent grains can be used as a significant portion of an animal’s diet. So, if you’re looking for a source of inexpensive feed, raise a glass at your local brewpub or tap room, then ask to speak to the brewer.