Animal welfare officials say most of the hundreds of roosters seized from a suspected illegal cockfighting site will have to be euthanized.

The Massachusetts Society for the Prevention of Cruelty to Animals, which is housing the birds at its farm in Methuen, says the roosters are extremely aggressive and cannot be rehabilitated or retrained.

Northampton police seized about 400 birds from a farm in the city last Friday. About three-quarters of them are roosters bred for fighting.

Officials discovered signs of cockfighting during a barn inspection, including the birds, gloves used during fights and a bag of medication commonly used in cockfights. Cockfighting is illegal in all 50 states.

The farm's owner says he rented the space to another person and had never been inside.

There have been no arrests.