Hog farmers are continuing to expand production in the face of rising feed costs prompted by the drought, an Agriculture Department report showed Thursday. As of June 1, the U.S. inventory of hogs and pigs was estimated at 56.2 million head, up 8 percent from a year ago and 15 percent more than two years ago. Industry analysts had expected a smaller increase. The number of breeding hogs, at 7.53 million head, was up 7 percent and 17 percent from June 1 of 1987 and 1986, respectively. That indicated further production increases in the months ahead. Officials said the June 1 inventory of market hogs _ animals headed for slaughter and the consumer market _ totaled 48.7 million head, up 8 percent and 15 percent from the previous two years. The pig crop during the first half of the hog marketing year that began last Dec. 1 was estimated at 46.6 million head, a gain of 8 percent from a year ago and 15 percent from two years ago. Looking at future prospects, the report said hog farmers surveyed intend to have 6.2 million sows give birth in the June-November period, a 7 percent increase from the same six months of last year and 14 percent more than two years ago. But the report cautioned that the farrowing intentions ``do not reflect conditions after the June 1 survey date.'' Leland Southard of the department's Economic Research Service said in a telephone interview the industry had expected the total inventory to be up only about 4 percent as of June 1. But Southard said ``a spike in feed costs'' has raised doubts about further expansion, however. ``I think there is a question whether producers will carry through with these farrowing intentions to the extent that they've indicated (in the June 1 survey),'' he said. ``We can blame that on higher feed costs ... costs of production.'' The following list shows the June 1 inventory in the 10 leading hog states, which account for about 79 percent of the nation's pork. The first number, in thousands, is the total number of hogs in the state, the second is the June 1 figure's percentage of a year earlier.