According to a recent paper in the Canadian Veterinary Journal, there is a good chance that the calves you buy will be infested with lice.
Researchers discovered that more than 95 percent of beef calves that enter feedlots are lice-ridden.
In a study centered in Western Canada, researchers looked at calves that came from auction markets (multiple sources) and calves that came from one ranch in southwestern Alberta (a single source).
They diagnosed lice by checking the hair coat of each calf for the presence of adult lice and their eggs. Surprisingly, a higher percentage of ranch calves were infested than those from auction markets. This could be because the ranch calves had never been treated for lice. Some of the calves from the auction may have been treated – there was no way to confirm their history.
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In the end, the difference between the two groups was not significant since infestation levels made it necessary to treat all calves.
The long-nosed sucking louse was the most common species identified. In the first winter of the two-year study, more than 95 percent of calves were infested with this parasite. In the second year, 86 percent were infested, but some mixed infestations were seen. Thirty-eight percent carried more than one species.
Researchers were unable to determine the economic impact of infestations. Earlier studies have shown lice affect weight gains in feedlot animals.
Several studies have demonstrated that high lice densities will slow gains and lower feed efficiency while low numbers of parasites have no significant effect on production.
The problem is we don’t know how many lice are too many and if treatment costs can be offset by improved productivity.
The validity of treatment programs could be determined if the true cost of lice infestation was established. This would be valuable for feedlot operators if it prompted cow-calf producers to treat their animals before they leave the ranch.
Facts about lice
- Both sucking and biting lice can be found in Western Canada. Lice cause skin irritation that triggers an intense itch that cattle will do anything to alleviate.
- Lice infestations cause the coat to look greasy and dirty. Blood-laden lice may be squashed when infested cows rub, smearing their coats with their own blood.
- Lice have been reported to reduce calf birth weights and lower weight gains.
- Blood-sucking lice can also cause anemia from prolonged blood loss. This can lower immunity and predispose cattle to infections such as respiratory disease.
- Producers can diagnose lice by looking for adults on the skin of their cattle and by spotting the pale, translucent eggs or nits attached to hair shafts.
- Lice spread from one animal to another through close physical contact, especially rubbing. Calves easily become infested while suckling their dams.
- It has been recognized for some time that lice numbers peak during the winter. It’s not known why, but one suggestion is that immunity falls at that time of year, allowing lice to flourish. Closer confinement in winter may also contribute to higher numbers.
- It takes three to four weeks for an egg to hatch and develop into a sexually mature adult louse. When adult lice are removed from cattle, they can only survive a few days. Unfortunately, lice eggs can act as a source of infestation for other cattle because they continue to hatch for several weeks in warm weather.
- Any building that has housed infested cattle must be cleaned and left empty for a while before restocking with lice-free animals.
- Lice can be effectively treated with insecticides, many of which are applied topically. To achieve good control, the entire herd must be treated simultaneously.
