Jerold C. Hoffberger announced yesterday that he will step down as chairman and chief executive of Carling National Breweries Inc., of Baltimore, on Saturday. He will remain on the board of directors and become a consultant to the nation's tenth largest beer firm, Hoffberger added.

Carling National, like other smaller beer manufacturers, has been struggling to maintain a market share (2.3 percent of U.S. beer sales) in the wake of volume growth by the two largest brewers, Anheuser-Busch and Miller Brewing. The Justice Department announced last month that it would oppose the proposed merger of Carling National into Pabtst Brewing Co. of Milwaukee, No. 4 in the industry.

Hoffberger's departure comes after 30 years with NationalBrewing Co., or Carling National, the result of a 1971 merger of National and Carling's U.S. business. Hoffbergersaid yesterday it is "time to make room" for other leadership in the firm. He will continue as chairman of the Baltimore Orioles baseball team and as a director and chairman of the executive committee at Fairchild Industries, based in Montgomery County.

Peter Codd, executive vice president, will become acting chief executive of Carling National Dawson Farber, vice chairman, will be acting chairman.