Tyson has reported a jump of 15 times in third-quarter earnings but warned that, thanks to continued weakness in demand for meat, much of the improvement may prove temporary.

The US group, the world's largest meat producer, reported earnings of $134m for the three months ending on June 27, compared with $9m a year before.

The earnings figure, equivalent to $0.35 a share, trounced analysts' forecasts of a $0.22-a-share result.

However, while shares soared 5% in before-the-bell trading, investors' jubilation evaporated as they digested a warning from Leland Tollett, the Tyson chief executive, that less profitable times were on their way.

"Soft demand for protein is likely to make the fourth quarter more challenging than the third quarter," Mr Tollett said.

Tyson shares stood 1.9% lower at $11.21 in official trading in New York at 14:00 GMT.

'Oustanding performance'

The group's third-quarter improvement reflected higher volumes of chicken sales, which garnered higher prices too.

With acquisitions also chipping in, divisional revenues grew 7.1% to $2.42bn, an "outstanding performance", Ken Goldman, a JP Morgan analyst, wrote.

While sales of beef and pork slipped, dragging group sales 2.7% lower to $6.66bn, both feed prices and administration charges fell faster.

The group added that it had, for a second quarter running, made a "substantial" cut back on inventories leaving it better placed to ride out fresh market weakness.

"I'm feeling much better about our position than I would be if we were sitting on a lot of inventory," Mr Tollett said.