A festival believed to be the largest animal sacrifice ritual in the world began Friday in southern Nepal, where devotees believe the sacrifices bring good luck and a Hindu goddess will grant their wishes.

In the fields outside a temple before dawn, a priest dropped five drops of his own blood and sacrificed a rat, chicken, pigeon, goat, and pig to start the festival. More than 5,000 buffaloes were ritually killed during the day.

Many other animals will be killed during the two-day festival at Gadhimai temple in the jungles of Bara district about 160 miles (100 miles) south of Katmandu.

Organizers and the authorities defend the festival held every five years as a generations-old tradition, though animal rights activists decry it as barbaric. During the 2009 festival, an estimated 200,000 animals and birds were sacrificed.

Most people who attend the festival are from neighboring India, even though that country bans the export of animals for the festival.