The state Gambling Commission says about 300 birds seized in a cockfighting raid on Monday at Rochester were killed.
A spokeswoman says about 240 roosters and 60 hens were euthanized, although several birds are saved as evidence in the case.
A 35-year-old Rochester man was arrested and accused of raising and training birds to sell for cockfights in Oregon, Texas and Mexico.
The Olympian reports the roosters were outfitted with spurs on their legs to inflict fatal injury.
Court papers in the case say the suspect said each rooster was worth at least $100.
The raid was the result of a two-year investigation by state Gambling Commission agents and Thurston County sheriff's detectives.