Tyson Foods Inc. began a hostile $941.2-billion tender offer for Holly Farms Corp., its biggest competitor in the poultry processing business. Memphis, Tenn.-based Holly Farms, which earlier this week rejected a $900-million bid from Springdale, Ark.-based Tyson, said it would study the sweetened $52-a-share offer. Securities analysts said they expected Holly Farms to fight a takeover attempt. Investors apparently expected bidding for Holly Farms to continue, although Tyson said it would not raise its offer any further. Holly Farms stock rose $2.75 to $53.625 a share in New York Stock Exchange trading.