Storey's Guide to Raising Chickens (41 page)

Gapeworms
— red fork-shaped worms that invade the windpipe, causing gasping, coughing, and head shaking (in an attempt to dislodge the worm). These parasites are quite serious in young birds, as they can cause death through strangulation.

Flatworms
are far less common in chickens than roundworms are. Flatworms fall into two categories:

Tapeworms
(
cestodes
) — long, white, ribbonlike segmented worms that invade the intestine, causing weakness, slow growth or weight loss, and sometimes death.

Flukes
(
trematodes
) — broad, leaf-shaped worms that attach themselves either inside the body or beneath the skin. Flukes are a problem primarily in swampy areas and where sanitation is abysmal.

To control parasites effectively, you have to know something about their life cycles. Some have a direct life cycle; others have an indirect life cycle.

DIRECT LIFE CYCLE OF ROUNDWORM

Worms with a direct life cycle live in a chicken’s body and shed eggs that pass out with the chicken’s droppings and are eaten by the same or another chicken to begin a new cycle.

INDIRECT LIFE CYCLE OF ROUNDWORM OR TAPEWORM

Worms with an indirect life cycle shed eggs that pass out with the chicken’s droppings and are eaten by an intermediate host, which is then eaten by the same or another chicken to begin a new cycle.

In a direct life cycle,
a female parasite inside a chicken’s body sheds eggs that are expelled in the chicken’s droppings. The infective parasite egg may then be eaten by the same chicken or by a different chicken. Assuming the parasite is a guest of the chicken it invades, the chicken becomes its host. A direct-cycle parasite goes directly from one host to another.

In an indirect life cycle,
parasite eggs expelled in a chicken’s droppings are eaten by some other creature, such as an ant, a grasshopper, or an earthworm. A chicken cannot become infected (or reinfected) by eating a parasite egg but rather becomes infected (or reinfected) by eating a creature containing a parasite egg. Because the parasite goes from a chicken to some other host and back to a chicken, the other creature is called an intermediate host. Parasites requiring an intermediate host are said to have an indirect life cycle because they cannot infect one chicken directly after leaving another. Most roundworms and all tapeworms are indirect-cycle parasites.

Pastured chickens are most likely to be infected by indirect-cycle parasitic worms whose life cycles involve ants, earthworms, slugs, or snails. Litter-raised flocks are likely to be infected either by direct-cycle parasites or by indirect-cycle parasites involving beetles, cockroaches, or earthworms. Chickens housed in cages are likely to be infected by parasites whose life cycles involve insects that fly.

PARASITIC WORMS AND THEIR HOSTS

Under proper management, including good sanitation, chickens gradually develop resistance to parasitic worms. A bird that has the opportunity to acquire resistance through gradual exposure to the worms in its environment gets an unhealthy load only if it is seriously stressed, such as by crowding, unsanitary conditions, or the presence of some other disease. Treating your chickens without knowing whether or not they have worms is a waste of money and may actually be harmful because:

It interferes with the chickens’ development of resistance to parasites.

It can cause parasite populations to become drug resistant.

Rather than deworming indiscriminately based on the biased advice of dealers who make a living selling poultry drugs, a more sensible approach involves having fecal samples examined periodically for signs of worms, then developing a deworming schedule based on your flock’s need. A veterinarian will do a fecal test for a few dollars. By taking fecal samples to your vet on a regular basis (perhaps every 3 months for a year), you can find out whether or not your chickens have a parasite problem and whether the problem varies in severity with the season. For example, most intermediate hosts proliferate during warm weather — becoming dormant in winter in northern areas — so you may need to deworm only once a year, in autumn. In a warm, humid climate, intermediate hosts thrive year-round, requiring more aggressive measures for controlling the intermediate hosts or deworming.

If you prefer to avoid drug use, sooner or later someone will tell you that the best way to keep chickens free of worms is to feed them diatomaceous earth (DE), sometimes called fossil flour, consisting of diatom fossils ground into an abrasive powder that supposedly shreds delicate worm bodies. But when diatomaceous earth gets wet (as it does when combined with a chicken’s saliva), it
softens and loses its cutting edge, and once it passes through the gizzard it’s too ground up to retain any sharp edges. But feeding your chickens DE won’t hurt, and it contains a large number of beneficial trace minerals, so go ahead if it makes you feel better.

Protozoa
are simple and tiny creatures, some of which are harmless while others cause serious illness. The protozoa most likely to infect chickens are
coccidia
.
Coccidiosis
is the most common cause of death in young birds.

Although many different animals may be infected by coccidia, the species that infect chickens do not affect other kinds of livestock. The opposite is also true — chickens cannot get coccidiosis from other animals.

Coccidia have a direct life cycle. For each egg that hatches in a chicken’s intestines, millions are later released in the bird’s droppings. All ground-fed birds are exposed to coccidia throughout their lives, but a properly maintained pastured flock is less likely to become infected than birds living in crowded conditions, housed on damp litter, or allowed to drink water fouled with droppings.

Gradual exposure to coccidia allows a chicken to develop immunity. In young birds that are not yet immune, illness or death occurs when poor sanitation exposes them to too many coccidia too rapidly. Chicks raised in a wire cage and later moved to a coop with litter have had little exposure and therefore have no immunity and can become seriously infected. Even mature birds can become infected in hot, humid weather when coccidia proliferate more rapidly.