Most mature horses only need about 10% crude protein in their diet. If fed an adequate amount, grass hays can often fill this need. | Photo: iStock

Q.My horse maintains his body condition well on forage alone, but I’m worried he doesn’t have enough protein in his diet. Can horses get enough protein from hay alone?

A.There is a common misconception that grass hays (which are the type of hays most commonly fed to horses) don’t provide horses with adequate protein. However, most mature horses only need about 10% crude protein in their diet. If fed an adequate amount, grass hays can often fill this need.

Mature Horses’ Protein Requirements

According to the Equi-Analytical feed database, on average, grass hay provides 10% crude protein on an as-fed basis. A 500-kilogram (roughly 1,100-pound) horse at maintenance has a crude protein requirement of 630 grams. If fed 2% of his body weight (10 kilograms or 22 pounds) of this grass hay, the horse will receive 1,000 grams of protein—plenty to fill his needs. The same horse in very intense work requires about 1,004 grams of crude protein each day, so this hay at this intake can meet a broad range of