[1] Univ Bristol, Div Farm Anim Sci, Bristol BS40 5DU, Avon, England
[2] Univ Bristol, Food Refrigerat & Proc Engn Res Ctr, Bristol BS40 5DU, Avon, England
[3] Vet Labs Agcy, Addlestone KT15 3NB, Surrey, England
[4] Food Stand Agcy, London WC2B 6NH, England