The Relationship of Serum Protein Bound Iodine Levels to Rates of Gain in Beef Cattle

Abstract

The serum protein bound iodine levels have been determined in a total of 54 beef calves, 8–11 months of age, in 3 feeding trials. These levels were compared to subsequent or concomitant feed lot gain. The results indicate that groups of Hereford and Aberdeen Angus calves which show a wide variation in protein bound iodine exhibited a wide variation in rate of gain. In 10 individually fed Hereford bulls, a high correlation between efficiency of gain and this iodine level was evident. Under certain conditions a negative correlation between the level of protein bound iodine and feed lot gain was observed. A study of a group of Aberdeen Angus and Hereford bulls indicates that this negative correlation exists only in animals which have an optimal or higher level of protein bound iodine. A low level may be accompanied by lowered rates of gain.