Whether I meet Owen Brennan at his home in Beauparc or at Devenish’s research farm in Dowth, both within a short distance of Newgrange in Co Meath’s historic Boyne Valley, the first thing he shows me is trees. Then he moves on to the wild flower meadow that has replaced his front lawn, the wild deer roaming the sprawling Dowth estate, and the many archaeological features in between.  At first, this all seems very remote from Brennan’s successful global feed ingredients business, which I’ve come to discuss. The Devenish group posted £225 million in revenues in 2018, growing the figure…