By Justin Walker
Communications Specialist
A common pest—lice—can bite into ranchers’ profits during the winter season when longer coats on cattle provide ideal conditions for populations to grow and hinder herd health.
Dr. Jason Banta, Texas A&M AgriLife Extension Service beef cattle specialist, said longer and thicker hair helps cover and protect the pest, resulting in better reproduction rates.
While lice can infest cattle at any point in the year, the longer winter coats found from December to March provide the ideal environment for them.
“Lice will cause reduced appetite in a herd, which means reduced performance,” Banta told AgriLife Today. “It’s important to be aware of the pest this time of year.”
Lice can also reduce red blood cells, and Banta noted livestock with large infestations can become anemic.
Two types of lice—biting lice and sucking lice—can affect cattle herds, according to Banta.
Sucking lice are usually found around the head and neck areas, while biting lice can be found on the neck, shoulders, back and rump. Sucking lice are the more invasive of the two, but biting lice cause the most irritation.
Symptoms include rubbing, biting, scratching and hair loss on the neck, shoulders and rump.
Lice are transmitted through physical contact.
Treatments can be relatively easy, but Banta stressed the importance of understanding the development of lice. The life cycle is 20-30 days and takes place entirely on the host, making it relatively easier to kill the parasite. Adult females lay their eggs on hairs, hatching 5-14 days later. Two weeks later, the nymphs are fully-grown, egg-laying adults.
“It’s important to know that available treatment products don’t kill the eggs,” Banta said. “Many control methods will take two treatments before the life cycle is broken. And always treat every animal in the herd, because that one you don’t treat will be the one that causes another infestation for you to deal with.”
Traditional insecticides like Cylence or many permethrin-based products require an initial insecticide application to decrease populations and another application two to three weeks later.
Standguard and Clean-up II only require one treatment, Banta said. Pour-on dewormers like Eprinex, Cydectin and Dectomax only need to be applied once for control all season.
Banta also warned that some treatments, such as an injectable dewormer, will only handle sucking lice and won’t control biting lice.
“If they use injectable dewormers, make sure you use a pour-on insecticide to take care of the biting lice,” Banta said.
Spraying is also an option, but doing so in cold conditions can cause stress to the animal. When spraying, it’s important to wet the entire animal to ensure the skin and hair have been properly soaked.
Once treated, Banta said the herd should be prepared for the remainder of winter and through the summer season.
“After the treatment regimen, your cattle will typically be in good shape until the next fall or winter,” he said. “Treat them, control them and you’re done.”