PERFORMANCE OF FEEDLOT CATTLE WITH PARASITE BURDENS TREATED WITH AN ANTHELMINTICS

Two studies were conducted to evaluate the performance of cattle infec ted with liver flukes and gastrointestinal nematodes after treatment w ith doramectin or ivermectin/clorsulon. One study evaluated weaned cal ves; the other, yearling steers. Before placement in the feedlot pens, one group received doramectin and the second group received ivermecti n/clorsulon; the third group included nonmedicated controls. Fecal sam ples for nematodes egg counts and fluke eggs were taken pretreatment a nd on day 84. Hot-carcass weights, quality grades, yield grades, and l iver condemnations were recorded at slaughter. Compared with controls, both treatment groups demonstrated improved average daily gain, feed efficiency, and hot-carcass weight. The advantages of the treatments w ere probably related to removal of gastrointestinal nematodes based on reduced nematode egg counts and positive fluke egg counts at day 84 a nd liver condemnations (due to liver flukes) at slaughter.