Dietary Aroclor 1254 in the Milk Fat of Lactating Beef Cattle

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Abstract
Excretion in milk fat of Aroclor 1254 (a mixture of polychlorinated biphenyls) by mature beef cows (Hereford and Hereford crossbred) was studied. Groups (3) of 6 cows each were fed primarily a corn silage diet characterized by clean silage (stored in an uncontaminated silo), silage stored in a silo coated with a sealant containing Aroclor 1254 and clean silage to which 200 mg Aroclor 1254/head daily was added (.apprx. 2-3 mg/kg body wt per day). Treatments were started .apprx. 3 mo. prior to parturition and extended 1 mo. after parturition, at which time treatments were discontinued and cows and nursing calves were placed on pasture. Milk was sampled from parturition-132 days after discontinuance of treatments. Fat from the milk of cows fed silage from the silo not sealed with the Aroclor 1254 product contained 0.69-1.59 ppm Aroclor 1254 throughout the 164 day lactation. Fat from cows fed silage from the silo treated with Aroclor 1254 sealant contained > 10-fold as much Aroclor 1254 (15.7-18.4 ppm) for 32 days compared with controls and then dropped to 1/2 that through the 164th day. Fat from the milk of cows fed 200 mg Aroclor 1254/day contained 119-150 ppm through the 1st 32 days and then dropped to 39-51 ppm through day 164.