1. Department of Dairy and Food Science, The Royal Veterinary and Agricultural University (KVL), Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark; Department of Agricultural Sciences, KVL, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark; and Department of Plant Biology, Danish Institute of Agricultural Sciences, Research Centre Flakkebjerg, DK-4200 Slagelse, Denmark