- Animals: goats
- Animal Production: animal protection and health, manure management
- Crop Production: food product quality/safety
- Education and Training: display, extension, on-farm/ranch research, technical assistance
- Farm Business Management: whole farm planning, budgets/cost and returns
- Natural Resources/Environment: biodiversity, habitat enhancement
- Pest Management: biological control, prevention
- Production Systems: agroecosystems, holistic management
- Soil Management: earthworms, soil quality/health
- Sustainable Communities: partnerships, community services, sustainability measures
Haemonchus contortus, the barberpole worm, is a blood-sucking gastrointestinal parasite of special importance in small ruminants. Goats infected with H. contortus suffer from reduced productivity, anemia, and eventually death. Due to the overuse of chemical dewormers, H. contortus has become resistant to all available classes of dewormers.
Alternative methods of controlling H. contortus infections include the use of forages high in tannins, copper oxide wire particle boluses, selective breeding, rotational grazing and maintaining pasture forage heights above 4 inches. No one of these methods is capable of completely controlling H. contortus. Alternative methods will have to be part of a comprehensive integrated pest management (IPM) program designed to reduce H. contortus infection rates to manageable levels. Reduction of fecal material on pastures could reduce the parasite egg load on the pasture. Most methods of manure management on pastures require a tractor to pull a harrow or similar object over the pastures to break up manure to speed drying and expose parasites to predators and the elements.
Development of additional H. contortus control strategies is necessary to protect small ruminant producers in the southeastern United States against unsustainable economic losses due to gastrointestinal parasites.
Project objectives from proposal:
The proposed project will identify coprophagous and nematopredacious species present on farms in Arkansas. Species identified as potentially useful in controlling H. contortus larval survival will be propagated. Propagated species will then be used to increase the population on the farm from which they were collected and changes in H. contortus infection rate based on FAMACHA scores and fecal egg counts will be measured.
A sustainable method of managing manure on pasture could involve coprophagous species that are easily managed, readily available, inexpensive, and already shown to be beneficial or harmless to the environment. Dung beetles (Geotrupes, Orthophagus, Aphodius, Bubas spp.) rapidly remove manure from the surface of pastures and bury it below ground. Dung beetles have been widely used in Australia to reduce surface manure deposits and have been shown to be effective in reducing Bush fly and Buffalo fly emergence (Lancaster and Hunter, 1978). Dung beetles released in Texas were shown to be effective in reducing horn fly numbers as well. Fincher (1973) noted that the number of gastrointestinal parasite larvae and the infection rate of calves grazing plots with higher numbers of dung beetles were lower. Additional benefits of dung beetles in pastures are increased plant growth and nitrogen content, and improved air permeability of the soil (Bang et al., 2005).
Some researchers have suggested that dung beetles may not be effective in reducing the number of nematode larvae by burying the manure (Waghorn et al., 2002). However, they merely simulated the action of dung beetles by burying sheep manure in a core 50 mm deep, then covered with 25 mm of soil. The larvae only had to pass through a cm of soil, yet many dung beetle species bury dung up to a meter in depth. Others have found that under controlled conditions, “dweller”-type dung beetles may actually improve parasitic nematode larval hatch and survival (Chirico et al. 2003). Fincher (1973) reported that there appeared to be two peaks of larval activity and proposed that the second peak could be due to larvae burrowing up from less than a few centimeters below the soil surface. Neither peak reached levels achieved on plots where dung beetles were excluded.
Other species that may assist in reducing the survival of H. contortus on pastures have been less well-studied. Earthworms (Lumbricidae) have been shown to reduce the presence of gastrointestinal parasites on pastures (Holter, 1979; Grønvold, 1987). Similarly to dung beetles, earthworms break apart manure pats, facilitating desiccation, consume parasite larvae and bury parasite larvae deeply enough that few survive the trek to the surface to infect ruminant hosts.
Mites, such as Lasioseiuspenicilliger may consume H. contortus larvae before they can migrate from the manure to nearby plants (Aguilar-Marcelino et al., 2010;Quintero Martinez et al., 2010).