Disappearance of 4-(2,4-Dichlorophenoxybutyric) Acid Herbicide in the Dairy Cow

Abstract
The herbicide 4-(2,4-dichlorophenoxybutyric) acid, (4-(2,4-DB)) is used for broadleaf weed control in forage crops. A method based on electron affinity gas chromatography was developed for its determination in forage. In the work reported, this method has been applied to follow the disappearance of the herbicide in dairy cows. Feeding 5 ppm of the herbicide in the feed of a dairy cow resulted in no residue in the milk or feces. Five ppm of the herbicide fed to a fistulated heifer largely decomposed within 5 hours in the rumen.