Eighty percent of the ponies in the hay-only group gained weight—adding an average of about 5% of their body weight. | Photo: iStock

“Our study suggests that straw isn’t dangerous for ponies—at least the ones in our study population—and it can be used to induce weight loss in ponies living in the field year-round while keeping their hunger satisfied,” said Miranda Dosi, DVM (Hons) MRCVS, an equine medical resident at the University of Edinburgh Royal Dick School of Veterinary Studies.

Dosi and her fellow researchers observed 40 mixed-breed ponies over a four-month period (December to March) as they consumed either a normal ration made up entirely of hay or the same ration composed of 50% local U.K. hay and 50% unchopped barley straw. All the ponies in the straw/hay group lost weight (dropping about 5% of their body weight, on average). Eighty percent of the ponies in the hay-only group gained weight—adding an average of about 5% of their body weight.

“Straw is a forage that’s high in fibers while low in proteins and sugars, leading to gradual weight loss,” Dosi said. “It’s not as palatable as hay, but they’ll eat it if they’re hungry