Prevention of Parasitic Gastroenteritis in Second-Season Beef Cattle with Topical Ivermectin

Abstract

In the U.K. and Ireland, parasitic gastroenteritis is a serious threat to the health and welfare of young cattle during their first season on grass (1). Disease and consequent production losses are usually prevented by strategic anthelmintic therapy associated with appropriate pasture management. One such system which takes advantage of the prolonged activity of ivermectin formulations involves the treatment of calves at 3, 8 and 13 weeks after turn-out (2). Less is known about the epidemiology of parasites in cattle during their second season on grass, however, it is recognized that immunity to Ostertaqia ostertaqii, the most important gastrointestinal parasite, is slow to develop (3). There are no previous publications on the use of an early-season anthelmintic suppression system using ivermectin for second-season grazing cattle. A trial was conducted in Northern Ireland to determine the parasitological and production effects of treating second season cattle with topical ivermectin at 3 and 8 weeks after turn-out.