By Diane Schivera, M.A.T.
Ectoparasites (parasites that live on the outside of the host) can cause large financial losses to livestock farmers if not managed in a way to reduce populations. Itching and skin irritations cause animals to scratch, rub and bite infested areas. Blood loss, depressed appetite and decreased rate of weight gain are all possible and result in reduced production. A serious infestation can cause animals to be irritable – a potentially dangerous situation, especially with large livestock!
Lice are generally host-specific; they can feed on only one or a few closely related species of animal host. Mites are not as host-specific as lice and can parasitize many animal species. Some mite species spend their entire lives on the animal; others are present only during active feeding periods and retreat to nearby protected locations after feeding.
Biosecurity is the easiest way to prevent many ectoparasites from infesting your livestock. Have a place separate from your existing herd or flock where you can isolate new animals brought on your farm for three weeks, if possible. When doing chores, go to the isolation area last and don’t wear the same clothes during your next chore time. If you are observant, you can catch infestations early by checking itchy animals on areas of skin that are more likely to be attacked (tail, head, sensitive skin around the ears, scrotum or vulva). When only a few animals are affected, this isolation space can also house animals that are being treated.
A generously sized, easily available dust bath helps prevent ectoparasites on poultry. The dust bath can contain a sand and clay mixture and be deep enough that birds can dust themselves well. To increase the effectiveness of the dust bath, you can add 1/4 cup each of diatomaceous earth (DE) and wood ash to each gallon of soil or sand and clay, but don’t add more, because these materials irritate the respiratory system. Wear a dust mask when mixing the dust bath. Many farmers use wood ash alone – not mixed with soil, sand or clay.
The life cycle of the parasite is important in deciding how to treat any infestation. For lice that spend their entire life on the animal, treating just the animal suffices. If the parasite can survive in the environment, then the environment must also be treated or must not be used for a sufficient period.
The overall health of the livestock, including their nutritional status, stress levels and even genetics, will impact their susceptibility. Research by the UMass Belted Galloway Group showed that “Up to 2% of a beef herd can be considered ‘carriers” or ‘chronics.’ This refers to animals that carry a moderate to high number of lice throughout the entire year, specifically in the summer when infestations are know to be uncommon.” Due to contact with these animals, lice could not be eliminated in the herd using various conventional and organic methods of treatment. (https://www.agri-dynamics.com/pdfs/Ecto-Phyte-vs.-Cydectin-Research–University-of-Mass.pdf)
So feed your animals a quality, nutritionally balanced diet including access to minerals. Feed them kelp to produce a shiny coat and to reduce problems with lice and mange. Make sure they are not crowded and that they have space to exhibit natural behavior, including something to scratch on. Do not let them stay wet for long periods, without being able to dry out. Exposing livestock to as much sunlight as possible is the simplest way to control ectoparasites. Replacement stock should come from your healthiest, most disease-resistant breeding animals.
Many treatment methods exist. Repeat any treatment twice in seven- to 10-day intervals to kill newly hatched pests, because treatments rarely kill eggs. Parasite control is most important in the fall and early winter when populations increase. Unfortunately, sheep parasites are easiest to control after the animals are shorn in spring.
Diatomaceous earth (DE) effectively eliminates soft-bodied pest lice – but remember to protect yourself and the birds from this respiratory irritant. A combination of turmeric and neem bark powders as a dust has also been shown to be effective against lice.
An essential oil, e.g., peppermint oil, in a gentle soap used as a drench can be effective.
Smothering can kill scaly leg mites in poultry. With a paintbrush, apply vegetable or linseed oil on the birds’ legs when they are on the roost at night. Mixing the oil with an essential oil, such as tea tree oil with antibacterial properties, helps the healing process. It is important to repeat this process for three or more nights in a row and again in a week to 10 days.
Some pyrethrin products, e.g., pyganic, are permitted for organically certified animals. Follow the label dilution recommendations for a liquid. Use caution when treating animals with a liquid in cold weather; if they don’t have the opportunity to get dry, a liquid is not the best treatment option.
To control mange, use sulfur powder, pyrethrum powder or lime sulfur. These work on the larvae as they migrate on the surface of the skin.
For additional information, see MOFGA’s fact sheet, “Raising Organic Livestock in Maine,” at https://www.mofga.orghttps://www.mofga.org/wp-content/uploads/2021/01/FS-Raising-Organic-Livestock.pdf.
Note: If you are raising certified organic animals, always check with your certifier before using any new products
Common Ectoparasites of Livestock
Body lice – Menacanthus stramineus
Head lice – Cuclotogaster heterographus
Lice survive for only a few days to a week if separated from their host.
Red poultry mites – Dermanyssus gallinae
Feed on poultry at night, hide in crevices of poultry house in daytime. Survive off the bird for six months.
Northern fowl mites – Ornithonyssus sylviarum
Spend entire life cycle on the bird, day and night. Can survive off the host for two or three weeks.
Scaly leg mites – Knemidocoptes mutans
Spend entire life on the bird, under the leg scales of the chicken’s shanks.
Cattle chewing lice – Bovicola bovis
Long-nosed cattle lice – Linognathus vituli
Short-nosed cattle lice – Haematopinus eurysternus
Little blue lice – Solenopotes capillatus
Spend entire life on the host animal.
Female lice lay eggs/nits by attaching them to hairs with a strong glue-like substance.
Chorioptic mange, barn itch – Chorioptes bovis
Mites live on surface of the host animal’s skin, feeding on lymph and dead cells.
Sarcoptic mange – Sarcoptes scabiei
Mites burrow under skin to lay eggs; larvae move to the surface and burrow new tunnels.
Do not live long off the host.
Ticks – Borrelia burgdorferi
Carry Lyme disease and Babesia
Sheep and Goats
African sheep lice – Linognathus africanus
Sheep foot lice – L. pedalis
Sheep body biting lice – Bovicola ovis
Feed on skin scales and wool fibers. All suck blood.
Psoroptic mange – Psoroptes ovis
Eradicated at this point.
Ticks – Borrelia burgdorferi
Carry Lyme disease and Babesia
Fly strike, wool maggots – Lucilia sericata
Flies lay eggs on wet or dirty area of skin, under wool. Larvae develop and live on decayed skin and other material. Sheep with damp fleece, diarrhea or wounds are susceptible.
Sheep keds – Melophags ovinus
Wingless flies resembling a tick, 1/4-inch long with a broad, leathery, unsegmented, saclike abdomen covered with short spiny hairs.
Hog lice – Haematopinus suis
Spend entire life on the animal.
Sarcoptic Mange – Scarcoptes scabei
Mites spend entire life cycle on the hog; dig beneath the skin.
Diane Schivera is MOFGA’s organic livestock specialist. You can reach her at 568-4142 or [email protected].