For the quarter ended March 30 net income dropped to $0.8m from $27.2m last year although sales rose 11% to $828m from $746m in 2002.
Coors said it was also hit by interest and pension expenses and lower US shipments to wholesalers, compounded by a blizzard in Colorado in March.
The brewer said that for its UK business, negative customer, channel and brand mix shifts impacted the results “more than expected”. However, chairman Peter Coors said it was likely that “many of these challenges will abate as the year progresses”.
Chief executive officer Leo Kiely said: “The first quarter of this year was even tougher than we thought it would be.
“However, despite a challenging start to the year, we believe that the first quarter is not indicative of our potential for the year.”