(Adds economist quote, details)
July 25 (Reuters) - Tyson Foods Inc, the largest U.S. meat processor, said it will discontinue operations at three of its factories which make frozen foods such as pepperoni, pizza crusts and meat dishes, affecting about 950 people.
Tyson, which won the bidding war for Hillshire Brands Co in June, said the closures were not related to the acquisition.
"The decision to close these plants was underway long before the (Hillshire) discussions began", Tyson spokesman Gary Mickelson told Reuters.
Tyson outbid Pilgrim's Pride Corp with its $63 per share offer for Hillshire, valuing the Jimmy Dean sausages maker at $8.55 billion.
The company said the plant closures were due to changing product needs, the age of the Cherokee, Iowa factory and the distance of the Buffalo, New York and Santa Teresa, New Mexico plants from their raw material supply base.
The closures come as the number of beef cattle in the United States is at its lowest level in 63 years due to severe droughts, reducing the amount of meat available to process.
"The consolidation helps them get transportation efficiencies," Chris Hurt, an agricultural economist with Purdue University, said. "It clearly helps them get operational efficiencies."
The Cherokee plant will close on Sep. 27, while the Buffalo and Santa Teresa plants are expected to stop operating in the first half of 2015, the company said.
The U.S. Department of Labor's Occupational Safety and Health Administration had cited the Buffalo factory for workplace safety hazards in November an proposed fines of about $122,000. (http://1.usa.gov/1xd7EVs)
The closures will affect 450 employees at Cherokee, 300 at Buffalo and 200 at Santa Teresa. The company had about 115,000 employees as of last September.
Shares of the company, which will report quarterly results on Monday, were little changed at $39.49 in extended trading on Friday.
(Reporting by Sruthi Ramakrishnan in Bangalore and P.J. Huffstutter and Tom Polansek in Chicago; Editing by Joyjeet Das)