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

Departments of Entomology and Dairy Science, Cornell University, Ithaca, N. Y.

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 (1, 2) was developed for its determination in forage (3). This method has been applied to follow the fate of the herbicide in dairy cows.

EXPERIMENTAL PROCEDURE

A. Jersey cow was fed 5 ppm (based on a daily ration of 50 lb) of 4-(2,4-DB) for four days. The pure herbicide in ethyl alcohol was mixed with the grain. Samples of milk and feces were taken up to 1 wk after the feeding and were analyzed for the herbicide.

The method of analysis consisted of blending 25 g of milk or feces with 70 ml of acetone and 1 ml of 85% phosphoric acid. The solids were filtered off and the filtrate was made to a total volume of 100 ml with acetone. One milliliter of this solution was evaporated in a 10-ml volumetric flask and the contents esterified with 2 ml of BF₃-methanol reagent (4).