Management of Lice on Cattle

By Conor Ryan

Over the winter months, housing provides us with an exceptional opportunity to revise the animal health plan we have in place on our farm. After the mild autumn, lice burdens will be relatively high. Heavy lice burdens will cause animals to itch which will act to reduce the Live Weight Gain (LWG) as the feed intakes are affected from the itching. Lice are a parasite that will survive for up to 5 days without an adult host (cattle) and it is of paramount importance the effect of lice is not overlooked as we go through the winter housing period.

Lice are divided up into two main groups: 1) Biting lice and 2) Sucking lice. Biting lice feed on the skin and hair of the animal and it is not uncommon to find these lice located on the head, neck, or the rump of the animal. These biting lice have a large, round head. Biting lice can cause severe irritation for the animal and if the infestation is very bad the wound that is created from the lice will become more susceptible to a secondary bacterial infection which will further reduce the thrive of the animal. Sucking lice on the other hand are configured in such a way that they can pierce the skin of the animal and feed on their blood & bodily fluids. The sucking lice thus have a relatively small, narrow head which will aid in the sucking process. Both types of lice have eggs or nymphs that can glue themselves to the hair of the animal and they hatch after two weeks. It is important to be able to differentiate between the two common louse types.

In order to identify lice in the herd it is important to look out for animals that are rubbing, biting, scratching or suffering from hair loss due to rubbing on the neck, shoulder and rump region. Once identified the use of an insecticide will treat the infected cattle. Again, it is important that you can identify whether the lice are sucking or biting as the treatment may vary for both. For example, the use of an ivermectin (avermectin) such as Ivomec Super will be more effective against the sucking lice, and as a result it will not result in the complete elimination of biting lice. On the other hand, a pour-on pyrethroid solution will act against both biting and sucking lice. These pyrethroid pour on products will work by moving through the fat layer of the animal and if these products are used correctly then they are very effective in treating the lice. The use of a deltamethrin based product such as Spot-on will provide exceptional cover against lice. Alternatively, the use of a cypermethrin based product such as Liceban or Ectospec will also provide an emphatic treatment of lice. Lice as a parasite can move freely between the animals so it is also important that all the animals in the herd are dosed not just the ones that are visually affected. All these products are widely available in your local Liffey Mills branch.

Often two separate treatments three weeks apart will be required to ensure the lice are properly treated. This is to kill the eggs that will have hatched since the previous treatment. Animals that are previously diseased or nutritionally stressed are more susceptible to a lice infestation, so it is important to keep our animal health husbandry in tip top shape all through the housing period!

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