Beef specialist: Producers should control lice in cold weather

WEST LAFAYETTE, Ind. - Beef producers should be on the lookout for lice infestations and have a plan for controlling the spread to prevent animal stress, a Purdue Extension beef specialist says.

"Now is the time when lice populations are going to become a noticeable problem," Ron Lemenager said. "We've got cold weather and heavy winter hair coats on cattle, and that's the perfect scenario for lice populations to increase and become evident."

Cattle with lice infestations will rub against trees, fences and buildings, irritating their skin and damaging property. Lemenager said lice can disrupt feeding behavior, reduce milk production, increase weight loss and result in an unthrifty appearance.

Persistent rubbing and loss of hair should be a warning to producers that cattle have a lice problem.

"Lice infections can be confirmed by parting an animal's hair and looking closely to identify the small, flat-bodied lice attached to the hair and skin," Lemenager said. "Heavily infected cattle can take on a greasy appearance from rubbing, and skin will be raw and red."

This additional stress can make cattle more susceptible to disease, and it hinders productivity in grow-finish cattle, cattle experiencing cold stress and cows within the herd.

While there are many species of lice, biting and sucking lice are two of the most common. The biting louse has a yellowish-white body with a triangular head and is commonly found near the base of the tail and along the topline. Short-nosed sucking lice are gray or black and are usually found along an animal's neck, ears, dewlap and brisket.

Producers should use an insecticide to control lice. Endectocides, systemic products that are commonly available in pour-on and injectable forms, are effective against both internal and external parasites and have some residual control.

But Lemenager cautions producers to be aware of the timing of their applications because the best time to control external parasites may not be the best time to control internal parasites.

Another control option is non-systemic insecticide, which is available in more forms, but typically needs to be applied twice to kill the eggs as well as live lice.

"The safe way to go is to treat cattle with a non-systemic insecticide. They come in pour-ons, dust bags, sprays and cattle rubs that can be applied," Lemenager said.

Lemenager offered these tips for treatment:

* Treat every animal in a group at the same time to prevent reinfestation. Keep treated and untreated groups separate.

* Read and follow product label directions for correct dosage, application site, timings and any precautions regarding withdrawal times prior to slaughter.

* Make sure the insecticide gets in the hair and down to the skin where it can do the most good. Pour-on insecticides are usually best for this.

* When using a non-systemic insecticide, a second application will be needed as a follow-up in three to four weeks to help eradicate lice that have moved from egg to adult stage.

About 1 percent to 2 percent of the cattle population, usually older cows and bulls, are carrier animals that can reinfect the herd. While total eradication of lice is unlikely, Lemenager said timely application of the right products can keep lice populations low and greatly reduce animal stress.

Writer: Amanda Gee, 765-494-8402, agee@purdue.edu

Source: Ron Lemenager, 765-494-4817, rpl@purdue.edu

Ag Communications: (765) 494-2722;
Keith Robinson, robins89@purdue.edu
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