Two days before Thanksgiving, Wal-Mart (WMT) slashed prices on hundreds of grocery items, a welcome break for consumers but the first shot in what is sure to be a price war between mainstream grocers and the largest seller of food in the United States.

Wal-Mart, also the world's largest retailer, has already cut prices on toys, appliances, electronics and apparel to attract more holiday shoppers. The retailer also recently initiated a $4 generic prescription drug program that threatens pharmacy chains.

Now, it is trimming prices on hundreds of fresh and dry food items.

The retailer said that the price of many food items would be lowered by as much as 20 percent. Some items were discounted more heavily.

The prices of some items for Thanksgiving dinners are being slashed. A six-ounce box of Stove Top stuffing sells for 88 cents, down from $1.44 to $1.74 per box. A can of Ocean Spray cranberry sauce is now 88 cents, down from $1.14 to $1.36.

Among the other rollbacks, a 26.4-ounce pack of boneless skinless chicken breasts from Pilgrim's Pride Corp. (PLG), Tyson Foods Inc. (TSN) or Perdue will now sell for $4.74, or $2.87 per pound, down from $5.35, or $3.24 per pound.

The retailer, which is based in Bentonville, Arkansas, said the lower prices, or rollbacks, would be in effect throughout the season.