Treatment of North Dakota beef cows and calves with ivermectin

A 2-year field study was carried out in North Dakota, USA to determine if there was an economic benefit from treating cows and/or their calves with ivermectin (Ivomec) at 200 µg/kg sc. Three herds were used; each herd was divided into 4 similar groups: group I - cows and their calves treated with ivermectin (cows in the autumn and calves in late June); group II - only cows treated each autumn; group III - only calves treated in late June; group IV - neither cows nor their calves treated. A total of 953 calves were weaned over the 2-year period. Calves were individually weighed at weaning and the actual market value (based on local market conditions) of each calf was calculated. Calves in groups I and II averaged at least 20 lb more than calves in group IV at weaning; this difference was significant. Calves from cows treated with ivermectin returned a significant economic benefit over controls.