An outbreak of foot and mouth disease in Indonesia threatens to disrupt a ritual of slaughtering animals to mark the Qurban Bayram (aka Eid al-Adha) this year, with livestock traders in the world's largest Muslim-majority nation bemoaning low sales.

Eid al-Adha, also known as the "Festival of Sacrifice," is one of the main holidays in the Islamic calendar and this year starts on July 9.

In the lead-up to celebrations, makeshift pens housing cows and goats typically appear around busy thoroughfares in the Indonesian capital and around the country. Traditionally, devout Muslims slaughter the animals and share the meat with the poor.

But this year the spread of foot and mouth disease, a contagious viral disease that impacts cattle, sheep, goats and pigs, has significantly dampened sales.

"This year is a year of loss for us," said Jamal Lulay, a trader in West Java who has only sold 50 cows this year.

"Before COVID-19, we could sell up to 330 cows, and during COVID-19 it was around 170 ... This year sales have dropped drastically."

Indonesia had launched a nationwide livestock vaccination program in an attempt to curb the outbreak that began this May.

More than 317,000 animals have been infected in 21 Indonesian provinces, largely on the most populated islands of Java and Sumatra, with more than 3,400 animals culled, according to government data.

While the disease can be lethal for animals, it is not generally considered a threat to human health.

"People's enthusiasm for sacrifice has not been diminished, but they are more worried about the health (of the animals)," said Muhammad Husein al-Bana, a livestock trader in Jakarta.

Until this May, the Southeast Asian country had been free of the disease since 1986, a status recognized by the World Organisation for Animal Health in 1990.

"Ultimately it is the consumer's decision," said Iskandar Saputra, a Jakarta buyer still willing to take the risk.

"I think the cows sold here are safe and healthy."