The Effects of Feeding Parathion to Dairy Cows

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Abstract
Two groups totalling 10 dairy cows in heavy lactation, representing 4 major breeds, were fed a commercially available wettable powder formulation of parathion at levels of 5 and 1 ppm., based upon an estimated roughage dry matter intake of 2.25 lbs. per 100 lbs. of body wt. daily, continuously for 81 days. These feeding levels represent an actual parathion intake of 0.112 mg./kg. of body wt. for the cows receiving 5 ppm. and 0.022 mg. for those receiving 1 ppm. based upon the estimated roughage dry matter intake. At the conclusion of this expt., two of these cows were fed increasing amts. of parathion up to 40 ppm. of the estimated roughage dry matter intake. In neither expt. was any parathion found in the milk of the exptl. cows by the use of both a chemical method of analysis for parathion involving a liquid-liquid extraction technic and biological assay using adult houseflies. No objectionable flavor was noted in the milk and no harmful effects to the health or reproductive ability of the cows were observed.