Implants and Feed Additives for Feedlot Cattle

The introduction of diethylstilbesterol to the cattle feeding industry in the early l 950's set a milestone in terms of adding an implant or additive to the feed and improving feedlot performace. The stilbesterol (not presently approved for use) caused feedlot cattle to gain about 9 percent more rapidly and reduced feed required for gain about 7-9 percent. The industry took many years to except and understand the stilbesterol concept. In the late l 970's the first ionophore was cleared for use in feedlot cattle and in less than 60 days following final clearance by FDA for this compound, it was reported that nearly 90 percent of the cattle on feed in this country were receiving Monensin.