[1] Univ Coll Dublin, Sch Agr Food Sci & Vet Med, Agr & Food Sci Ctr, Dublin 4, Ireland
[2] Univ Coll Dublin, Sch Biol & Environm Sci, Agr & Food Sci Ctr, Dublin 4, Ireland
[3] TEAGASC, Grange Beef Res Ctr, Dunsany, Meath, Ireland
[4] Scottish Crop Res Inst, Dundee DD2 5DA, Scotland