Parasites are a major contributor to production losses in goat herds. Effective parasite management is vital to increase production efficiency and weight gain.
The best way to prevent parasites is to monitor and deworm the herd as needed based on body condition, fecal egg counts (FEC), performance/production, pregnancy/lactation status, and signs of anemia.
Table of Contents
1. Monitoring
A parasite management strategy must include monitoring as part of the routine health check, especially in light of anthelmintic resistance. The first step is to carefully observe the group of animals and look for individuals who are not looking or acting as well as their peers. This will help to catch problems before they progress to disease and loss of production. Thoughtful observation involves watching both the behavior and the appearance of the goats. Watching for signs of a potential problem can include fatigue, difficulty standing, favoring certain limbs, mucus discharge, and lack of hunger. The general observation should be followed by a more thorough individual examination (health check).
Internal parasites breed inside the host and produce eggs that pass through the animal in feces. The eggs need warm, moist conditions to hatch and develop into larvae that the host can ingest. Larvae migrate out of animal feces up blades of grass (usually one to two inches high). When sheep or goats graze, they can take in these parasite larvae along with the grass.
The internal parasite population can become too large to manage with treatment and cause disease, illness, and production losses. It is important that all operations utilize a combination of treatments and management techniques to keep the parasite population under control. The American Consortium for Small Ruminant Parasite Control recommends using “smart drenching” that includes only treating those animals that are clearly infected with the current parasite challenge (using the FAMACHA system for haemonchosis or Body Condition Scoring for other parasites). Leaving a percentage of the herd untreated also decreases resistance development.
Another tool being used by some producers is a fungus that traps parasite larvae in the feces. Research has shown that this fungus significantly reduces parasite growth and can be used in place of traditional drenches.
Other tools include: rotating pastures and moving animals from fields that are heavily contaminated to other pastures to allow forage to regenerate; providing areas of browse on the ranch to decrease the amount of parasite eggs consumed from grazing forages; harvesting hay off pastures to decrease parasite egg counts; and decreasing stocking density to reduce the herd’s overall worm burden.
2. Deworming
Internal parasites (more commonly known as worms) are the greatest threat to goat health. These include the barber pole worm Haemonchus contortus, which feeds on the blood and causes anemia; tapeworms that attach to the lining of the digestive tract and can cause malnutrition; and flukes that can damage the liver. A number of different deworming medications are available to control these parasites. However, if an overly aggressive program is used, parasites can develop resistance to these drugs. As a result, it is essential that any drenching program is implemented with careful attention to the needs of the herd.
Deworming should be done on a regular basis. This is especially important in arid climates where parasites have a greater opportunity to build up resistance to anthelmintics. A good deworming schedule should be based on fecal egg count, body condition, age (kids/weanlings require full grazing seasons to develop immunity), performance/production, and pregnancy/lactation status (these dams are under higher stress and have reduced immunity).
For the most effective management of internal parasites, rotational grazing is an excellent tool. This means dividing your pasture into several smaller areas and rotating the goats from one area to the next, allowing the previous area time to rest. This interrupts the parasites’ life cycle and minimizes their population.
It is also important to deworm only the animals that need treatment. This has been termed “smart drenching” and is advocated by the American Consortium for Small Ruminant Parasite Control. By deworming only those goats that show clinical signs of parasitism and by culling those animals that require multiple drenchings, you are maintaining herd genetics that are naturally resistant to parasites.
Another strategy to use in conjunction with smart drenching is the “dose and move” method. In this practice, the herd is drenched and then moved to a different grazing area that has not been used for haying. This allows the first grazing area to recover and reduces the amount of anthelmintic that is lost to the environment. This method is also recommended for herds that require a periparturient drenching in early spring.
3. Prevention
Internal parasites are a major issue for most goat producers. These parasites can lead to decreased performance, weight loss, and even death. The development of resistance to most commercially available anthelmintics compounds this problem. A good management program is the key to keeping parasites under control.
Parasites breed inside the host animal and then shed eggs in feces. These eggs require warm, humid conditions to hatch and develop into larvae. Once hatched, the larvae migrate up blades of grass where animals can ingest them. Animals from contaminated feed troughs or pen bedding may also pick up parasites.
The use of a properly administered systemic dewormer like SAFE-GUARD (or a similar product) is a great way to control parasites in the herd. A drench gun designed for goats should be used to administer the drug so that each goat swallows the entire dose. Administering the medication slowly ensures that each goat will have enough time to swallow the drug, allowing it to end up in the rumen, where it will provide a killing dose.
Other prevention tools include rotational grazing and pasture management practices. Sheep and goats that are forced to repeatedly graze the same field can become heavily infected with gastrointestinal parasite larvae and eggs. In rotational grazing systems, relocating herds to different fields prevents over-grazing of the first two inches of forage growth which is where many parasite larvae reside. It is also a good idea to include hay fields in the rotation.
There are a number of breeds of sheep and goats that are more tolerant or resistant to parasitism than others. Producers should consider culling animals that are always “wormy” and selecting those that show a natural resistance or tolerance to parasitism. The ATTRA publication Tools for Managing Internal Parasites in Small Ruminants: Animal Selection provides information on selecting for this resistance.
Another new management tool being researched is the use of nematode-trapping fungi, which can be planted in the soil to reduce parasitic nematodes. Research has shown that these fungi can trap parasitic nematodes within the soil, interrupting their life cycle and reducing infection rates in herds. This is an exciting new tool that may help in the battle against internal parasites and is something to keep an eye on for the future of goat production.
4. Vaccination
Parasite control is one of the most important aspects of a herd health plan for any small ruminant producer. Internal parasites, particularly Haemonchus contortus (barber pole worm), are major production losses for many sheep and goat operations, and resistant strains of the worm have developed to nearly all commercially available anthelmintics. Vaccination as part of an overall parasite management strategy is crucial for the future of small ruminant livestock.
Vaccination is most effective when it is used as a tool in a herd health program along with other preventative strategies such as pasture management, herd isolation, and proper feed handling practices. Reliance on vaccination alone without a solid biosecurity plan and herd monitoring strategy is a recipe for disease outbreaks.
The main approach of parasite control for a grazing business should be pasture management. When sheep and goats chew on grass, they ingest infectious parasites larvae. The rate at which these are consumed is regulated by pasture management practices like rotational grazing systems, limiting stocking density, and providing areas with varying weed densities to shorten the time an animal spends on a given field.
Herd isolation is also an effective way to control parasites, as is avoiding the use of hay from fields that other animals have grazed in the past six months. In addition, feeding hay and grain in troughs that are not easily contaminated by fecal matter increases the safety of these feeds for herds with compromised immune systems.
Using only dewormers for sheep or for those animals that need treatment can help slow the development of resistance. We can help producers identify the individuals that need treatment with the FAMACHA system for Haemonchus, body condition scoring for other parasites, fecal egg counts, performance/production, and pregnancy/lactation status (these dams are under higher stress and have reduced immunity).
Lastly, a good record-keeping and vaccine-tracking system is necessary to ensure proper vaccination timing. It is helpful to have a set calendar for vaccinating animals, and it can be helpful to link these dates to a holiday, such as Valentine’s Day or Saint Patrick’s Day, to make it easier to remember when to treat each herd.