U.S. meat producer Tyson Foods Inc's second-quarter revenue rose more than expected on higher prices and the company forecast full year sales that would top Wall Street expectations.

High costs for grains, which are used in feed, pressured margins in the company's chicken business and earnings per share for the company came in a penny below analysts expectations.

Revenue was up 15.7 percent to $8 billion, beating the $7.54 billion expected by Wall Street.

Tyson expects full year sales of more than $32 billion, primarily because of price increases aimed at mitigating rising raw material costs, beating the $31 billion Wall Street analysts on average are expecting, according to Thomson Reuters I/B/E/S.

Springdale, Arkansas-based Tyson Foods earned $159 million, or 42 cents per share, for the quarter, on a par with last year's results. Analysts on average forecast 43 cents a share.

Chicken sales rose 10 percent to $2.74 billion as chicken volume rose 6 percents and prices rose 3.7 percent.

But operating margins in that unit, Tyson's second biggest, fell to 1.4 percent from 4.6 percent.

In the beef unit, sales rose 18.9 percent to $3.33 billion. Volume dipped 0.6 percent, but prices rose 19.6 percent.

Operating margin fell to 2.8 percent from 4.5 percent a year earlier.

Tyson shares were unchanged at $18.89 in premarket electronic trading.

(Reporting by Bob Burgdorfer and Brad Dorfman. Additional reporting by Phil Wahba in New York; Editing by Derek Caney, Dave Zimmerman)