Twenty lactating primiparous Holstein-Friesian cows @ days in milk were randomly allotted into four treatment groups that consisted of a wheat-based , pelleted basal diet with no supplemental CDCO ( control ) , basal diet with CDCO added at @ ml/kgDM ( DM ; dry matter ) ( low ) , @ ml/kgDM ( medium ) and @ ml/kgDM ( high ) in an eight-week feeding trial , after two weeks of adjustment .