Ron Foster announced Thursday that he will step down as president and chief executive officer of Foster Farms, the poultry company founded by his grandparents 75 years ago. Foster, 56, will remain an owner and board member with Foster Farms, which has a vast chicken processing plant next to its Livingston headquarters and a pair of turkey plants in Turlock. The business grew 70 percent over the 11 years Foster was at the helm, according to a news release. He had to deal over the past year and a half with a salmonella outbreak tied to raw chicken from Livingston and two Fresno plants. Federal authorities said it sickened at least 634 people, but they noted that the company carried out extensive measures to reduce future risk.