Almost a third of all milk consumed in the UK is produced by Wiseman Dairies
Robert Wiseman Dairies has announced its full-year pre-tax profits were up 60% to a record £49.2m.
The East Kilbride-based firm said the results had been boosted by a rise in cream prices and a £1.9m cut in a fine from the Office of Fair Trading (OFT).
Alan Wiseman has announced he will step down from the company in July and be replaced as chairman by his brother, Robert.
Wiseman produces almost one third of the fresh milk consumed in the UK.
The company achieved record sales in the year to 3 April, increasing the number of litres sold from 1.62 billion to 1.77 billion.
A fine imposed on the dairy group by the OFT relating to an investigation into price fixing was reduced from £6.1m to £4.2m.
However, Alan Wiseman warned of uncertainty in the future.
He said: "While the group has recently benefited from higher cream revenues, there is no certainty that these will recur.
"In the absence of a reversal in recent increases in plastic and fuel costs, then consideration will need to be given as to how the impact of these cost increases can be mitigated."
Mr Wiseman, who will step down as a director of the company at its next AGM in July, joined the group straight from school 43 years ago.
In 1976 he and his brother Robert took over the running of the company.
Robert Wiseman will move from chief executive to executive chairman when his brother leaves.
The current finance director, Billy Keane, will assume the role of managing director.