The board of Holly Farms Corp. rejected...

The board of Holly Farms Corp. rejected a sweetened $63.50-a-share offer from chicken producer Tyson Foods Inc., saying it was unsure that its rival could guarantee a successful merger. Springdale, Ark.-based Tyson, the nation’s largest chicken processor, raised its offer from $60 in a pre-dawn meeting Thursday, said Tyson spokesman Jim Blair. The bid values Memphis, Tenn.-based Holly at $1.15 billion.