Sustainable Agriculture

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Tipsheet: Organic Management of Internal and External 

Livestock Parasites

Photo: Robyn Metzger, NCAT

Livestock parasites are present on our farms. They have many attributes that allow them to survive difficult environments and seasons, and it is literally impossible to completely eradicate them. When parasite numbers are too high 

for the host animals’ immune systems to control, we will observe signs of disease, including weight loss, appetite loss, 

depression, weakness, and, if not treated, death.

Yet animals have always coexisted with these parasites. The keys to coexisting include:

y A strong immune system

y Low exposure to parasites

A strong immune system is naturally present in some animals. Selecting those breeds and individuals is part of a good 

animal-health strategy. Immune systems are encouraged through good nutrition and low stress, including healthy living conditions and calm handling.

Meanwhile, exposure will not overwhelm the strong immune system if parasite numbers are kept low. This is accomplished through sanitation (clean water tanks and feed troughs) and through pasture management. 
Page 2 Tipsheet: Organic Management of Internal and External Livestock Parasites

Several keys to preventing illness from parasites are stated in the United States Department of Agriculture (USDA) 

National Organic Program (NOP) Livestock Health Care Practice Standard (7 CFR §205.238) at www.ams.usda.gov/nop 

(click the Organic Regulations link, then scroll down to 205.238). 

y Producer must use preventive practices, including the following:

 Select species and types of livestock suitable for local conditions and resistant to prevailing diseases and 

parasites

 Provide adequate nutrition

 Establish housing, pasture conditions, and sanitation practices to minimize occurrence of diseases and 

parasites

 Keep stress low

y When the above measures are not enough to prevent sickness, a producer may use synthetic medications, 

provided they are allowed under §205.603 (the National List of Allowed and Prohibited Substances, www.ams.

usda.gov/NOPNationalList) but ONLY in certain circumstances. These include:

 Breeding stock, when not in the last third of gestation but not during lactation for progeny that are to be 

sold, labeled, or represented as organically produced

 Dairy stock, when used a minimum of 90 days prior to producing organic milk

y A producer is PROHIBITED from:

 Using synthetic parasiticides on a routine basis

 Using synthetic parasiticides on slaughter stock

There is very limited use of certain parasiticides allowed in organic production. However, organic producers are obligated to treat sick animals, even if it means the animal loses organic status (check §205.238(c)(7)). For example, if a group 

of young lambs becomes parasitized and organic treatments fail, the producer is required to treat them with effective 

treatments. Then one of two situations will apply:

1. If animals are treated with synthetic dewormers on the National List, they are no longer eligible for organic 

meat or fiber production. Such treated animals are eligible for organic milk production after a withdrawal 

period. 

2. If animals are treated with synthetic dewormers NOT on the 

National List, those animals may no longer produce organic 

milk, meat, or fiber. However, they do not have to be removed 

from the herd as they may be used as breeder stock. 

Producers must identify and note clearly in the records which treated 

individuals no longer have organic status. 

Internal Parasites

Internal parasites can become a problem under certain circumstances:

y Where there is a concentration of susceptible animals;

y When weather is humid and warm, or when pastures are irrigated;

y For young stock before immunity has developed;

y During times of stress, especially for females giving birth 

and lactating;

y When animals are grazing and are left in one area for too 

long;

y When animals are returned to a grazing area too soon. Lactating females and young stock are more susceptible to internal parasites. Photo: Robyn Metzger, NCAT
www.attra.ncat.org Page 3

Grazing management is the single most important thing a producer can do to prevent illnesses from internal parasites. 

See ATTRA’s Tools for Managing Internal Parasites in Sheep and Goats: Pasture Management for a full discussion on this topic. 

Principles apply to other livestock as well, though cattle are less susceptible than sheep or goats to internal parasitism. 

y Do not allow livestock to graze shorter than three or four inches, because internal parasite larvae will be concentrated near the ground level, generally speaking. 

y Use multispecies grazing to break parasite cycles; cattle do not share parasites with sheep or goats. Sheep and 

goats DO share parasites.

y Allow pastures to rest by grazing with a different species of livestock or cutting for hay before coming back to 

graze the same pasture again. A 60-day rest will also help internal parasite levels naturally die back.

y Provide diverse pastures. Having many forage species present will promote intake and also improve the nutritional quality available for the livestock. Some plant compounds may have medicinal properties that promote 

animal health.

y Provide browse. Internal parasite larvae will not be present on the leaves, and the plants may provide medicinal substances as well. 

y High-tannin forages such as sericea lespedeza have been shown to reduce fecal egg counts in sheep and goats. 

See ATTRA’s Tools for Managing Internal Parasites in Sheep and Goats: Sericea Lespedeza for more information. 

y Graze younger, more parasite-susceptible stock first on fresh pasture that is less contaminated by parasite larvae to help protect the health of these more-vulnerable animals.

Providing excellent nutrition, including trace minerals, will help livestock by boosting their immunity, making them 

less susceptible to parasites and other diseases. 

Good sanitation is also essential to encouraging good animal health and minimizing internal parasites and flies. Remove 

manure and keep water and feed troughs clean. 

Selecting animals that have inherent resistance to internal parasites is required by the USDA organic regulations. 

Keep good records and cull those animals that are most susceptible. See ATTRA’s Tools for Managing Internal Parasites 

in Sheep and Goats: Animal Selection for an explanation of why and how to identify your strongest livestock. 

Organically Acceptable Dewormers

If you farm or ranch in a region with high internal-parasite pressure, then you have a particularly difficult challenge. 

There are very few organically allowable products available to assist you.

Diatomaceous earth (DE) often is touted as a parasiticide and is commonly used by organic producers. Although it is 

heavily promoted as a dewormer, the efficacy of DE has not been proven. If you choose to use DE, make certain that 

Related Publications Available 

from ATTRA 

Organic Principles of Animal Health

Treatment of Sick or Injured Organic 

Livestock

Managing Internal Parasites in Sheep and 

Goats

Raising Organic Pigs: A Guide to USDA Certified Organic Requirements 

Coccidiosis: Symptoms, Prevention, and 

Treatment in Sheep, Goats, and Calves

Coccidiosis in Poultry

Blackhead in Turkeys

Multispecies grazing can help break parasite cycles. Photo: Robyn Metzger, NCAT
Page 4 Tipsheet: Organic Management of Internal and External Livestock Parasites

it is part of a more comprehensive parasitemanagement plan. Also be certain that you 

are using an organically allowable form of diatomaceous earth (not the kind used for pool 

filters), and remember to consult with your certifier before adding new health products into 

your Organic System Plan (OSP). 

Several herbal agents also are reputed to be useful for deworming livestock. Their efficacy has 

not been shown. The Sustainable Agriculture 

Research and Education (SARE) program offers 

many opportunities to learn about research into 

innovative or alternative internal-parasite control. Go to www.sare.org and click on “research 

reports.” Using “internal parasite” as the search 

term will bring up many research reports from 

all SARE regions. Learning about the research 

that already has been done can save a lot of 

effort, time, and money—and improve the wellbeing of your animals.

External Parasites

Common external parasites, also known as ectoparasites, are lice, mange, 

keds, and ticks. External parasites cause reduced rates of weight gain 

and loss of animal condition, and they decrease production rates due 

to animal discomfort (e.g., skin irritation) and blood loss. 

Environmental and weather conditions contribute to ectoparasite infestations. In humid areas, for example, external parasites such as ticks are 

more common in animals that graze close to woodlands. Animals that 

are in confinement and very close to each other and animals in cold 

weather conditions are prone to suffer from ectoparasites. Preventive 

strategies could include the following: 

y Segregating animals new to the farm for at least 21 days. They 

should be monitored closely and treated if necessary.

y Separating infested animals from the herd 

y Ensuring good feed quality and, for ruminants, a constant supply of free-choice minerals. Low stress and good nutrition help 

animals’ immune systems thrive.

y Employing stress-reducing practices, including the following:

 Providing adequate space for animals to exercise and for 

animals to eat without excessive competition

 Providing quiet, calm care when moving or otherwise working with livestock

There are several organic treatment options for external parasite infestations. These treatments are generally allowed, 

but not always effective. If you plan to use them, they should be listed in your OSP and monitored for efficacy:

y Liquid enzymes

y Diatomaceous earth and garlic powder

y Soap

y Organic plant oils (e.g., soy and canola)

Providing adequate space for exercise helps reduce 

animals’ stress and makes them less likely to suffer 

from external parasites. Photos: Robyn Metzger, NCAT
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Sunshine is another “treatment” known to be effective against lice infestations. Also, for calves, housing them separately 

will cut incidence of lice versus group housing. See the eXtension article listed below for more practical tips.

Talk with your certifier before using any treatment materials that are not listed in your OSP. 

Flies are another example of small but costly 

pests. Here are a few tools for managing fly 

populations organically:

y Sanitation practices that keep facilities clean and dry will reduce breeding 

grounds for flies

y Physical traps, including sticky tapes 

and larger fly traps

y Natural predators such as bats and 

predatory wasps

y Composting manure, mortalities, and 

afterbirths

If you get good control of the situation early 

in the fly season, it will be easier to keep the 

fly population down later in the year. Using all 

available tools will make this more manageable. 

Contact your Cooperative Extension Service for 

more on Integrated Pest Management (IPM) for flies and other pests. Another resource to consult is ATTRA’s Biorationals: 

Ecological Pest Management Database. This is a searchable database designed to help farmers and ranchers find preventative techniques and possible treatments for many pests and diseases. Organic Materials Review Institute (OMRI)-listed 

products are noted in the database. It can be found online at https://attra.ncat.org/attra-pub/biorationals. Remember 

always to check with your certifier before using any material and include your plans in your OSP.

Resources

Fly Management in the Organic Dairy Pasture Webinar

www.extension.org/pages/59441/fly-management-in-the-organic-dairy-pasture-webinar-by-eorganic 

This link includes the webinar, and a link to an excellent article authored by the presenters. The article, Integrated 

Pest Management Guide for Organic Dairies, is 38 pages long and covers life cycle, identification, and organically 

approved methods of controlling flies, lice, mites, and grubs. Both the webinar and the article are applicable to all organic 

livestock operations. 

Organic Dairy Herd Health: External and Internal Pests and Parasites

www.extension.org/pages/67228/organic-dairy-herd-health:-external-and-internal-pests-and-parasites

This is a concise article with helpful tips.

USDA Organic Regulations 7 CFR 205

www.ams.usda.gov/nop

USDA National Organic Program Handbook

www.ams.usda.gov/NOPProgramHandbook

USDA National List of Allowed and Prohibited Substances 

www.ams.usda.gov/NOPNationalList

Organic Materials Review Institute (OMRI) 

www.omri.org

Photo: Robyn Metzger, NCAT
Page 6 Tipsheet: Organic Management of Internal and External Livestock Parasites

Questions y Are you using organically allowed strategies and techniques for preventing and controlling internal parasites 

in livestock? Success is more likely when several of these strategies are used together. Options include, but are 

not limited to, the following:

 Pasture rotation 

 Controlled grazing

 Multispecies grazing 

 Dragging pastures to disperse manure piles

 Fecal sampling as a monitoring tool

 Selective breeding for resistant stock

 Sanitation

 Herbal treatments (use caution—see SARE research)

 Diatomaceous earth (use caution—see SARE research)

 Allowed synthetic anthelmintics; currently Ivermectin, Moxidectin, and Fenbendazole (limited use only)

Prohibited materials and techniques include, but are not limited to, the following:

 Most synthetic deworming agents (required to be used if medically necessary, even though the animal 

loses organic status)

 Ionophores—antibiotics that control protozoan parasites, such as coccidia 

y Are you using organically allowed strategies and techniques to control or prevent flies, mosquitoes, and external parasites? Options include, but are not limited to, the following:

 Pasture rotation

 Multispecies grazing 

 Dragging pastures to disperse manure piles

 Manure management 

 Sanitation

 Ventilation and moisture control

 Screening

 Fly parasites and other beneficial insects

 Bat conservation

 Purple martins and other insectivorous birds

 Walk-through fly traps

 Sticky traps

 Flying-insect traps

 Electric bug zappers

 Biological pesticides

 Diatomaceous earth

 Botanical pesticides and preparations

Prohibited materials and techniques include, but are not limited to, the following:

 Most synthetic insecticides and acaricides

 Synthetic insecticidal ear tags 
www.attra.ncat.org Page 7
Page 8 Tipsheet: Organic Management of Internal and External Livestock Parasites

Produced by the National Center for Appropriate Technology

www.ncat.org • 1-800-275-6228 (1-800-ASK-NCAT)

(Parent organization to the ATTRA Project, www.attra.ncat.org)

Tipsheet: Organic Management of Internal and 

External Livestock Parasites

By Linda Coffey, NCAT Agriculture Specialist

Published July 2015

This product was developed with support from

U.S. Department of Agriculture’s Agricultural Marketing Service, National Organic Program