Animal rights activists say the butchering of animals ranging from buffaloes to rats in the village of Bariyapur amounts to mass cruelty while local residents say the stench of death leaves them struggling to breathe.
But despite intervention from India's Supreme Court, which has ordered a ban on buffalo exports, big crowds are expected at the two-day Gadhimai Festival in southern Nepal, close to the border between the two countries.
An estimated 300,000 animals, including chickens, ducks, pigeons and pigs, had their heads chopped off or throats slit during the last festival in 2009, making it the world's biggest sacrifice of animals at any one site.
According to legend, the first sacrifices in Bariyapur were conducted several centuries ago when the Hindu goddess Gadhimai appeared to a prisoner in a dream and asked him to establish a temple to her.
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The practice of ritual sacrifice has a long history in the conservative, largely Hindu Himalayan nation, with devotees offering goats and buffaloes to gods during major festivals in the hope of bringing health and happiness.
"There are people who say we shouldn't sacrifice animals, but we have our beliefs," Gopal Adhikari, a 36-year-old civil servant who is offering up a goat to be slaughtered this year, told AFP.
"I had asked Gadhimai to help solve property complications of my family and she granted my wish" at a previous festival.
"We don't force anyone to sacrifice... People come of their own free will," Chaudhary told.