Dr. Jacquie Jacob Ph.D., University of Kentucky
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There are a number of intestinal worms that can infest poultry, including roundworms and tapeworms. A small number of worms do not usually cause health problems, but large numbers can affect growth, egg production, and health. Young birds are more commonly affected. Birds ingest the parasite eggs present in contaminated feed or water, or in intermediate hosts (e.g., insects, snails, earthworms or other small animals) that can naturally carry the eggs.
Some worms interfere with feed absorption, some transmit disease, and some can migrate into the blood and other organs.
Nematodes are roundworms that commonly affect chickens; examples include Ascaridia gali, Heterakis gallinarum, and Capillaria obsignata. Infective eggs are resistant to the environment and remain viable for years. Poultry with outdoor access are more vulnerable to parasites than conventional poultry raised indoors due to the intermediate hosts (e.g., grasshoppers, beetles, slugs, earthworms, and snails) that birds eat on range or pasture.
Routine monitoring programs are essential to worm control on the farm. There are two direct monitoring methods. One is to sacrifice a few birds in the flock and inspect their intestines for worms. Adult roundworms are usually found in the upper small intestine. Adult tapeworms can also be found in the upper small intestine just after the duodenal loop. Cecal worms can be found by snipping the end of the ceca and watching for small worms to wiggle out. Capillaria worms are harder to identify and require more effort. If a microscope is available, the surface contents from the first 10 inches of duodenum just past the duodenal loop may be examined. Scrape the mucosal surface with a knife and place portions of it onto a glass slide with a cover slip. The thin worms can be seen with the microscope.
An alternative method, which does not require sacrificing any birds, involves collecting 20-25 fresh fecal droppings from different areas in the house and pasture and placing them into a plastic bag. Fecal flotation is used to detect, identify, and count the different worm eggs. This is typically done at a veterinary diagnostic laboratory. Collected samples should be stored in the refrigerator when there is a delay in submitting the sample.
Some helpful strategies to decrease parasites in the environment include moving the birds often to fresh pasture or paddocks, keeping the birds in dry areas, and keeping the litter in the house as dry as possible. Try to limit contact with wild birds as they may be infected. Ingestion of worms and insects from freshly plowed ground may result in infection.
There are a few products that can be added to conventional poultry feed to control internal parasites. These drugs can NOT be used in organic poultry production. There are no materials that can be used to treat a worm infestation, especially in egg layers, but food-grade diatomaceous earth can be added to the feed to control minor infestations of Capillaria and Heterakis worms (Bennett et al., 2011). Diatomaceous earth consists of fossilized remains of diatoms which are a type of hard-shelled algae. Food-grade diatomaceous earth is different from the pool-grade used for swimming pool filters. Only food-grade diatomaceous earth should be used for worm control.
Examples of diatomaceous earth products:
There is interest in garlic as a treatment against roundworms, but research using the active ingredient in garlic (allicin) failed to demonstrate any effect on intestinal worm populations (Velkers et al., 2011).
If worm loads are found to be high, there are some things that can be done to reduce their levels (Small, 1996). For inside the poultry house, 60 lb of salt for each 1,000 square feet of floor can be used and left for two days. For outside pastures, rotate pastures and leave vacant for at least eight months. Once a year the birds should be removed from the run, and the ground covered with quicklime at a rate of 100 lb per 1,000 square feet. After three weeks, the whole run should be dug over to ensure that the worm eggs are killed. Keep pastures cut close so that sunlight can kill parasite eggs on the surface. Keep pastures well-drained, as moist soil promotes the infectiveness of the worm eggs.
Current research programs include biological control measures (De and Sanyal, 2009). Worms have a portion of their life-cycle outside of the host. The free-living or pre-parasitic stages exist on pasture and are thus potential targets. Biological controls in the future could include fungi, bacteria, viruses and predacious nematodes.
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This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.