Rodents, if not controlled, can cause serious economic loss through spoilage of animal feed, spread of pathogens, and damage to buildings and equipment, Teagasc has warned.

Teagasc adviser Eamonn Dempsey has said that rodent control is essential to ensure food hygiene and for the protection of human and animal health.

During winter, water and food sources for rodents can become scarce, leading to a rise in rodents turning up around farmyards.

Sharing tips on how to control rodents on farms, Dempsey said that farmers should check around the farmyard two to three times a week to identify areas that can harbour rodents.

Obvious entry points on buildings and doorways should be sealed with metal sheeting, hardware mesh or cement.

Animal feed should be stored in rodent-proof containers or sealed silos, and any spilled feed on the yard or around feeders should be removed.

Items like old machinery, pallets, scrap wood and plastic should be kept away from farm buildings.

Non-chemical controls

Dempsey said non-chemical control methods should be considered before rodenticide, depending on the severity of the infestation.

Farmers in the Co-operation Project stream of the Agri-Climate Rural Environment Scheme (ACRES) have the option to choose a rodenticide-free rodent control under the non-productive investments (NPI) where they can install up to six traps in the farmyard.

Dempsey said this action will allow for effective rodent control while preventing accidental or secondary poisoning of other animals.

Rodenticide use

If choosing to use rodenticide, only approved products should be used, and the information on the product label, including application details, manner and area of use, and safety information, should be followed.

The bait used should be appropriate to the conditions and circumstances of the infestation.

Rodenticide products can include meals, cut or whole grain, pellets, wax blocks, edible lards/gels/pastes, and foam.

Dempsey said it should be remembered that rats may carry bait away with them and hoard it, or drop it in areas where children or non-target animals can come into contact with it.

If uptake of the bait is poor, or the treatment is failing, a different bait should be used rather than simply increasing the dosage.

Bait stations for rats should be spaced 5-10m apart along roadways and around buildings. Bait should never be exposed to non-target animals and birds.

Animal that prey on rodents, such as the barn owl, can be exposed to rodenticide through secondary poisoning by feeding on rodents (dead or alive) that have those poisons in their systems.

According to Dempsey, it is important to inspect bait points regularly and not to leave rat bait down continuously for more than 35 days.

If using traps, place several of them in an area where rodent activity in obvious. It is essential that an initial inspection occurs on the following day to check whether non-target animals have been trapped.

Dead rodents should be removed using gloves, placed in sealed bags, and disposed of according to local waste rules.

Once a rodent infestation is controlled, effective measures to prevent reinfestation can include keeping cats or dogs on-farm, as well as encouraging the presence of birds such as barn owls, buzzards, or kestrels.