Emergency crews were called to the Moppity Road facility - which houses close to 40,000 pigs - at 5.30am.

The blaze destroyed 70 per cent of a 120 metre shed that contained weaners.

Three Fire & Rescue NSW tankers - including one each from Harden and Boorowa, five Rural Fire Service tankers, police and ambulance attended the scene.

RFS South West Slopes Zone manager Andrew Dillon said while the loss of pigs was significant, about 1500 weaners had been saved and moved to another shed.

A Riverina Local Land Services (LLS) vet and biosecurity officer from the Young office attended the scene once the fire was declared out at 8.05am.

They assessed between 50 and 60 fire-affected pigs.

A total of 33 weaners had to be euthanised.

“Unfortunately at this stage it hasn’t been confirmed but we’re looking at around 2500 pigs lost,” Riverina LLS biosecurity and emergency services manager Ray Willis said.

Mr Willis said LLS staff left the property at 11am and were awaiting clearance from police forensic investigators to return to help with the clean-up.

“We’ll also provide advice on the appropriate disposal and reducing the disease risk of the carcasses,” he said.

“I haven’t spoken to [the owners] but I would say they’re quite distressed.”

Young Police Inspector Ashley Holmes said there was nothing to indicate the fire was suspicious.

“It seems more likely it was a heating fault,” he said.

Forensic investigators were still on the property at 4pm.

Barwang RFS brigade remained on site with LLS officials until 10am for safety reasons and to assist staff.

Andrew Dillon praised the “excellent” response to the fire by his zone brigades, Fire & Rescue NSW, paramedics and the LLS.

Member for Cootamundra Katrina Hodgkinson - who has had many dealings with Wonga piggery owners - also congratulated all agencies for their fast and professional service.

She said she was devastated to learn of the loss of the significant number of weaners and passed on her deepest condolences to the owners and staff of the property.

While Young Fire & Rescue firefighters were battling the blaze at Wonga piggery, a second fire ignited in a chimney at the Commercial Hotel.

Cootamundra Fire & Rescue NSW - who manned the Young station in Lynch Street while Young firefighters were at the piggery - attended the scene at 7.30am.

Young Fire & Rescue NSW captain Ryan Terry said the fire was the result of a blocked chimney.

The two occupants living upstairs in the hotel managed to extinguish the fire and evacuate before firefighters arrived.

Firefighters - equipped in breathing apparatus - climbed the roof of the hotel to assess the chimney and ensure the fire was completely out, while local paramedics were on standby.