The French government called for a Christmas truce with protesting farmers, warning against further blockades during the holiday season, a move the country's main union said depended on the prime minister's response to their demands.

Farmers have been blocking roads, dumping manure and holding demonstrations in France for over a week to protest against the government's management of lumpy skin disease, a virus affecting cattle, and a trade deal with the South American bloc Mercosur.

Protests against culling

Farmers gathered with tractors early on Friday in front of President Emmanuel Macron's residence in the seaside resort of Le Touquet in northern France, placing a coffin labeled 'RIP Agri' and 'NO Mercosur.'

Meanwhile, in the southern town of Avignon, farmers threw potatoes at public buildings.

Protesters argue that the government's policy of culling an entire herd when lumpy skin disease is detected is excessive and cruel. They also claim the EU-Mercosur deal, whose signing has been postponed to January, would allow massive imports of products not meeting French standards.

Unions Coordination Rurale and Confederation Paysanne, which had been leading the blockades, said they would let farmers in each region decide whether to continue protests.

"We are very disappointed," Stephane Galais, spokesperson of the Confederation Paysanne, said after meeting Lecornu. "The decision will be taken locally, but I'll tell you this: we can't remove the blockades."

Galais said there had been no progress towards ending total slaughtering as a strategy to contain lumpy skin disease.

Young Farmers union President Pierrick Horel said members would observe a Christmas truce.

Mass vaccination drive

Earlier in the week, France deployed its army to accelerate the vaccination of cattle against lumpy skin disease, seeking to contain an outbreak that has fueled a new wave of farmers' protests in southern France.

The army flew in hundreds of thousands of livestock vaccines to southwestern France, and will assist in delivering shots to some 750,000 cows.

As farmers block highways, furious at a policy of slaughtering whole herds when the virus is detected, the government is accelerating vaccinations to quell the crisis, wary of disruption to year-end holidays.

President Emmanuel Macron has also responded by doubling down on a promise he will not endorse a European Union trade deal with the Latin American Mercosur bloc unless safeguards to protect Europe's farmers are toughened.

France procured 400,000 vaccine doses from the Netherlands to add to its stock of 500,000 vaccines. An A400M military transport plane delivered the extra shots to an army base in the city of Toulouse, army spokesman Colonel Guillaume Verne told reporters.

Livelihoods destroyed

The government is also drafting in several dozen veterinary doctors from the army to help with the vaccination programme in southern areas, including the remote Ariege region where few civilian vets are available.

The government aims to complete the vaccination programme within a month.

The authorities say the policy of culling herds is necessary to stop the disease spreading across France, which has the largest cattle herd in the European Union.

Some farmers' unions say the policy destroys livelihoods, adding to deep-seated grievances that include the planned Mercosur trade deal.

French farmers joined European peers at a protest in Brussels calling for an EU leaders' summit not to approve the trade deal.

Lessons from the Balkans

In 2016 several Balkan nations curtailed major epidemics of the same disease through swift action, mass vaccination and culls in about three months.

With no cases reported since 2018, Tamas Petrovic, head of virology at the Scientific Veterinary Institute in the Serbian city of Novi Sad, said the Balkans' response could offer lessons for this new outbreak.

When lumpy skin disease (LSD), or nodular dermatitis, was detected in nearby Greece and Bulgaria, Serbia was placed on alert and formed a task force to monitor its spread, said Petrovic, who was involved in the response.

Although the viral disease poses no risk to humans, it severely affects milk production and fertility and can be fatal in cattle.

As the prolonged incubation of the disease made it difficult to track and contain, officials quickly turned to vaccination, the researcher said.

But with no registered vaccine in Europe at the time, imports were ordered from South Africa.

Within a week of its arrival in Serbia, the vaccine was tested, and the first cattle vaccinations began. Mass vaccination was carried out in phases, with one million doses eventually administered across the country.

By first targeting large swaths of livestock in infected districts and then broadening out in three phases, the outbreak was quickly controlled, he said.

"We stopped the disease within two to three months after it entered the country," Petrovic said.

Insect control, culls and preventive campaigns

By 2018 the European Food Safety Authority (EFSA) said that more than 70 per cent of the Balkan region's cattle were vaccinated.

But vaccination alone did not stop the disease - several culls were needed across the region.

"If the disease appears, the euthanasia of the entire herd is mandatory," Petrovic said.

But rapid action meant fewer than 1,000 cattle were slaughtered in Serbia, out of a total herd of close to 900,000, Petrovic said.

Insect controls across the entire region also helped prevent the spread of diseases through mosquitoes, ticks and flies.

Petrovic said the Balkans proved to be "more than a good example" in controlling the disease.

Croatia's preventive vaccination, after EU approval, meant LSD was never reported in the country, despite outbreaks nearby in Serbia and Montenegro.

Its vaccination program effectively stopped the disease from entering the bloc at the time, he said.

Bosnia and Herzegovina also carried out vaccination and booster campaigns between 2016 and 2018.

As of 2019, the EFSA said that the disease had not been detected in the region, and preventive vaccination programs continued in high-risk areas.

The main lesson from that crisis was that experts must take the lead, Petrovic said.

"The state and politicians acted in line with the experts and followed what needed to be done - and they did it," he insisted.