Australia's Defence Force will dig mass graves for the country's burned livestock in a bid to fight off a biosecurity emergency.

Key points: The Agriculture Minister has offered 100 vets to bushfire-affected states to assess and euthanase thousands of stock injured by the blazes

The Agriculture Minister has offered 100 vets to bushfire-affected states to assess and euthanase thousands of stock injured by the blazes Bridget McKenzie says the bushfires will be devastating on the national herd, with stock dying from smoke inhalation and heat stress

Bridget McKenzie says the bushfires will be devastating on the national herd, with stock dying from smoke inhalation and heat stress She says when it's safe for Defence personnel to access the firegrounds, they'll be sent-in to dig pits and bury stock

Hundreds of thousands of animals have perished in the blazes according to early estimates, many of which are livestock, and more have abandoned paddocks that have had fences burned.

Agriculture Minister Bridget McKenzie said the bushfire crisis would "devastate" the national herd.

"I've got 100 vets across the country I've offered to state [agriculture] ministers," she told RN Breakfast.

"I know South Australia, Victoria and New South Wales will be taking up that offer to get that assistance as soon as possible — to not just assess the health, but these teams will also be euthanasing stock."

As of Monday afternoon, 3,872 animals had already been euthanased.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 9 minutes 4 seconds 9 m Former NSW fire chief Greg Mullins wants a more proactive response to the bushfire threat

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Biosecurity crisis countdown

Senator McKenzie said the dead animals presented a massive biosecurity risk and the Defence Force would help the clean-up, "to dig the pits, if you like, that are going to be required to bury this level of stock".

"It's about getting access to those still-live firegrounds but where it's safe to do so we need to be getting in within a week to really be dealing with the carcasses in an appropriate way".

James Zimmerman, a firefighter who helped defend Batlow on Sunday, posted on Facebook as he was defending the fires that they needed ammunition "to put livestock out of their misery".

Dozens of dead livestock on the side of the road outside Batlow. ( ABC News: Matt Roberts )

ABC journalist Tom Lowrey was in Batlow this morning to witness the devastation, saying dead livestock littered the road on the way into town.

"Farmers were this morning loading the charred bodies into utes — they said they did what they could, and saved many, but couldn't save all."

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Need for food and water

Farmers faced the prospect of fighting fires, repairing and rebuilding lost structures, as well as maintaining supply of produce.

"I'm hearing stories of farmers having to milk a dairy herd twice a day to keep the milk production up because if you stop milking you won't have any supply," Senator McKenzie said.

"[Farmers are] going around the farm and dealing with stock that need to be euthanased and then fighting the local fires.

"We're looking at very stretched, superhuman efforts here by our agriculture sector."

Dead livestock along the road into Batlow. ( ABC News: Tom Lowrey )

She said state farming organisations were requesting fodder and water.

However, there were risks that bringing hay into communities facing feed shortfalls would only increase the fire danger.

A lone sheep lies dead near Batlow, NSW. ( ABC News: Matt Roberts )

A delivery of 10 semi-trailers of hay into the fire-affected upper Murray region in Victoria had to be abandoned on Friday due to the ongoing bushfire threat.

"We don't want to put hay into fire zones and create more of a problem," Senator McKenzie said.

"But we also have to make sure we create a space for them to be accessible to farmers when and where they need it."