Meat producer Tyson Foods Inc. reported a higher-than-expected quarterly profit, but shares fell 4 percent on doubts the results can be sustained and that chicken prices may fall.

Tyson’s beef unit had a 5.6 percent profit margin versus 2.4 percent a year ago, while pork margins rose to 10 percent from 3 percent, helped by price increases because of a constricted meat supply.Analysts praised the results but said they would be hard to repeat. They do not expect the beef and pork segments to perform as well in the coming year, partly due to lower chicken prices, which tend to lure more consumers.

“We do not expect a repeat of this performance any time soon,” JPMorgan analyst Ken Goldman said in a note.

Goldman Sachs Monday initiated coverage of Tyson with a “conviction-sell” rating as it forecast lower chicken prices in 2011 amid an oversupply.

“I’m optimistic we will have a good year in beef and pork, it may not be the great, phenomenal year (like) this year, but it will be a good year,” Tyson Chief Executive Donnie Smith told Reuters.

Smith said the company was investing a major portion of its $600 million budget for capital improvements making chicken production and distribution more efficient. He said those improvements should lift the business enough to overcome any drop in Tyson’s pork and beef segments.

Tyson shares fell 4 percent, to $16.46, Monday. At Friday’s close, the stock was up nearly 40 percent year-to-date, but down nearly 17 percent from the year’s high of 20.56 set in April.

In the Reuters interview, Smith said Tyson’s feed costs are covered through the first quarter 2011, with corn at about $4 per bushel, in line with market levels.

Tyson’s earnings rose to $248 million, or 65 cents per share, in the third quarter ended July 3, from $131 million, or 35 cents a share, a year earlier.

Excluding one-time charges and income tax benefits, the Springdale, Ark.-based company earned 67 cents per share. On that basis, Wall Street expected 58 cents, according to Thomson Reuters I/B/E/S.

Revenue rose to $7.44 billion from $6.66 billion, beating analysts’ expectations of $7.26 billion.

The results came despite the loss of the Russia export market for chicken and the company having to pay higher prices for cattle and hogs.

In 2001, Tyson bought beef and pork producer IBP Inc to become the largest U.S. meat producer.

A smaller cattle herd this year reduced U.S. beef production and led to higher prices, with Tyson’s up 19.5 percent for the quarter. Cattle producers had reduced herds due to high feed costs and slow beef sales during the recession.

Beef accounted for 42 percent of sales, chicken 34 percent and pork nearly 17 percent. Prepared foods and other adjustments made up the total.

Tyson forecast 1 percent to 2 percent fewer cattle in fiscal 2011, which starts in October, but said there should be enough to efficiently run its beef plants.

Profit in the pork segment jumped to $125 million from $28 million a year earlier, helped by a 31.6 percent increase in prices and operating efficiencies.

Earnings in Tyson’s chicken unit, the nation’s largest, rose 30 percent on better margins.