COPPER STORAGE IN THE LIVERS OF CATTLE SUPPLEMENTED WITH INJECTED COPPER AND WITH COPPER SULFATE AND CHELATED COPPER

Cattle fed ad libitum a mixture of salt containing 0.5% copper as copper sulfate had an average increase in Cu concentration from 111 to 328 ppm on a dry weight basis in liver biopsy samples over a 333-day test period. The alfalfa hay ration contained an average of 8.2 ppm Cu and a relatively high copper to molybdenum ratio of 3.9:1. Copper supplementation from a variety of sources was given orally or by injection in an 87-day test. Chelated Cu was compared with Cu in copper sulfate, both mixed with salt, and with Cu injected as Cu calcium edetate. The ration of mixed alfalfa and grass contained 6.9 ppm Cu with sufficient sodium molybdate added to produce a Cu/Mo ratio of unity against which the various Cu sources were tested. There was no significant (P < 0.05) effect of Cu source on Cu storage in the liver. There were no trends (P < 0.10) for chelated Cu to result in higher levels of Cu in the liver than when Cu was supplied as copper sulfate even when chelated Cu was fed as fivefold the recommended levels.