Secretion of Heptachlor Epoxide in Milk

Twelve cows, fed alfalfa hay containing 0.08 or 0.29ppm heptachlor and heptachlor epoxide for 35 days, secreted into their milk an average of 17 and 9% of the intake, respectively, all in the form of the epoxide. A log-log relationship with a correlation coefficient of 0.97 was found between the amount of heptachlor plus its epoxide consumed and the concentration of the epoxide in the milk fat. Cows in early lactation secreted slightly more of their intake into their milk than cows in late lactation. However, cows in late lactation produced milk and milk fat with a slightly higher concentration of the epoxide than cows in early lactation. Jersey cows had a higher concentration of the epoxide per kilogram of milk than did Holsteins, but the Jersey milk fat had a lower concentration than did Holstein milk fat.