Just a quick question lately a some of my cows have been loosing hair on there rump. They are pregnant but now one of the calves is starting to loose a little. Are they just rubbing them or is something wrong?
There are a lot of products that will work well, just pick one that is easy for you to use depending on you facilities and the number to be treated. An injectable will not work for biting lice so it needs to be an external application .
Diatomaceous earth will work good. Hardwood ashes will too. Lice are common in late winter, but double check nutritional issues as weak animals tend to be prone to external parasites worse than critters in top health. Also the infestation will do more harm to sick ones.
Try the less toxic routes before escalating to heavier poisons.