HEAVY lamb prices have buckled in early new year markets, falling by up to $20 on Monday.

The stress of deteriorating paddock feed from recent bursts of hot weather and an abundance of numbers have forced prices down dramatically.

After a patchy trading week, prices were stripped back by $10 to $20 for extra-heavy lambs at Bendigo on Monday, with heavy mutton sheep following the trend to be $30 down.

"We copped it on the big lambs - it wasn't a good day at the office," said Rodwells Bendigo livestock manager Mick Crapper.

Agents stressed the price collapse is centred on very heavy lambs of 26kg-plus carcass weight.

Data collected by the National Livestock Reporting Service at Bendigo tell the story, with lines of extra-heavy 26kg-plus lambs averaging 359c/kg carcass weight or $132, compared with 494c/kg or $118.50 for the main drafts of 20-22kg trade lambs.

Mr Crapper said mild weather conditions late last year created a backlog of lambs.

"The season was four to six weeks late this year, and we are still cleaning up stock from areas like Kilmore and the North East that would normally have gone through the system in December," he said.

At Ballarat yesterday heavy export lambs, 24kg plus, were $3 cheaper on the heaviest pens, which sold from $131 to $145.

There were nearly 78,000 lambs offered at the major prime markets in Victoria last week, which is 20 per cent higher than the same time last year, the NLRS said.

Likewise, numbers were also up by 15 per cent in NSW, where nearly 77,000 head went through saleyards.

Elders Bendigo's Nigel Starick said it appeared exporters had limited kill space left to handle heavy lambs from the auction system.

"A lot of lambs have been booked in over the hooks, and that is dictating what competition we are seeing in the market place," he said.

Mr Starick is hopeful the current situation is short-lived and the lamb market will regain its price floor fairly quickly. "I've actually had buyers say to me just sit on the fence for a couple of weeks and the job will sort itself out," he said.