EAST MONTPELIER, Vt. — Erica Zimmerman and her husband spent months pasture-raising pigs on their farm here, but when the time came to take them to slaughter, an overbooked facility canceled their appointment.

With the herd in prime condition, and the couple lacking food and space to keep them, they frantically called slaughterhouses throughout the state. After several days they found an opening, but their experience highlights a growing problem for small farmers here and across the nation: too few slaughterhouses to meet the growing demand for locally raised meat.

In what could be a major setback for America’s local-food movement, championed by so-called locavores, independent farmers around the country say they are forced to make slaughter appointments before animals are born and to drive hundreds of miles to facilities, adding to their costs and causing stress to livestock.

As a result, they are scaling back on plans to expand their farms because local processors cannot handle any more animals.