Mr Brown, employed in November 1988, remains on full pay pending an investigation into why Daisy Hill has plunged into losses. Baker Tilly, a chartered accountancy firm and auditor to Usborne, has been brought in on the investigation.
Richard Endicott, finance director, said he hoped the investigation would be completed in time for the company to announce its delayed interim results next month.
There was no evidence so far to suggest that the problems at Daisy Hill were the result of any criminal activity, he added. No banking covenants had been breached.
One of the biggest problems affecting Daisy Hill has been the volatile and adverse swings in pig prices. Average market price for pigs last June was 118p a kilo, which dropped to 86p in October. The latest price is 100p.
Usborne, chaired by Lord Parkinson, the former Cabinet minister, owns more than 15,000 sows, reared on a contract basis at farms across the UK.
Losses at Daisy Hill are likely to pull the whole group, which made pounds 1.6m before tax in the 18 months to last June, into the red.
Richard Clarke, a farm business management consultant who has worked for Usborne before, has been appointed general manager of Daisy Hill.