Occurrence: Worldwide. Species affected: All. Age affected: All.

Causes: The Norwegian rat (Rattus norvegicus) and the house mouse (Mus musculus) are the most common rodents found around poultry houses.

Effects: Rats and mice cause damage to buildings and their foundations through chewing and burrowing activities. Both will eat poultry feed, and rats may also eat eggs in laying houses. Rats and mice are common vectors for many viral, bacterial and protozoal; diseases and can also carry ectoparasites.

Rodents are common external pests in and around poultry facilities and can parasitise poultry. Rodents can eat or contaminate feed, which increases feed costs and affects feed conversion. Additional problems can be produced by the presence of these pests, since they may carry a variety of diseases and ectoparasites.

The Norwegian rate (Rattus norvegicus) is the most common rat around poultry houses. Rats eat almost any type of food, including eggs and poultry feed; 200 adult rats will consume 25 lbs of feed daily.

Rat harbourage around a poultry house is seen in the form of burrows in the ground and under the foundation, litter under the slats, in wood piles, old nests and other debris near the poultry houses. This type of harbourage must be removed for any control program to be successful.

Most rat activity, including feeding, occurs at night. Rats observed outside their harbourage during the day indicate a large population. The best time for search for rodents and their excrement is at night in the dark with a flash light.

The house mouse (Mus musculus) is the most common mouse found in and around poultry facilities. Mice will eat almost any kind of food. Mice are active throughout the day, often feeding every hour. However, peak activity occurs at dusk and dawn. Mice breed regularly throughout the year with no seasonal peak.

Rodents can do a tremendous amount of damage if not controlled. They eat the contaminate feed, which increases costs and affects feed conversion. Rats may also eat eggs, so are a problem in layer and breeder houses. If present in very large numbers, rats may also attack birds.

Populations usually decrease during the winter, but in buildings the opposite is often true, as the animals migrate indoors.

Mice are more active at dusk and dawn, but are frequently active during the day. Peak rat activity occurs at night, so rats can best be found using a flashlight. Droppings in and around spilled feed and signs of gnawing and burrowing around the poultry house are indicative of rodents.

Rodent-proofing can be an effect long-term control measure. However, it is impossible to rodent-proof a poultry facility with curtains, wooden side walls and/or dirt floors. Access to the building can be restricted by patching or screening holes in the foundation, thus forcing the rodents to burrow into the house, which makes them easier to detect.

Sanitation involves cleaning around the facility. Rodents are secretive creatures, they do not like to move in open areas; therefore, mowing the grass and weeds on a regular basis creates a less favourable habitat. Removing piles of old wood, nests, or any other debris helps to make the area less attractive to rodents and aids in making early detection possible. When debris or tall grass is present, rodents can burrow into a facility and go unnoticed. Rolling the house curtains up and down a couple of times a week during summer months will disturb any rodents that are in the curtains and discourage them from living and/or nesting in them.

After the control measures have been completed, rodent-killing can be done by baiting, fumigating, trapping or even shooting. A properly conducted baiting program is easiest and most effective.

There are many products that will kill rodents. Safe and commonly used baits are the multiple-dose anticoagulants. Products that contain warfarin, fumaric, chlorophacinone, or diphacinone as an active ingredient are examples of this type. Multiple-dose anticoagulants must be consumed for several days to be lethal. The effects are cumulative therefore, it is imperative that enough bait be available for the rodents to eat for several days. These chemicals are safe for people and for non-target animals, because a single dose will not cause death.

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