Best practice use of rodenticides

Rodents and other wildlife can play an important role in the transmission of pig diseases that can compromise the health and growth of pigs, and may also affect people working in close proximity with the animals. Rodents are also responsible for a vast amount of damage, through their gnawing and burrowing to wiring and shed infrastructure.  A number of piggery fires have been caused by rodent activities.  When rodents live around farm buildings, they are a food source that can attract predators such as foxes or stray cats, and these, in turn, may contribute to disease problems. An effective disease barrier system cannot be achieved or maintained without good rodent control.

On-farm rodent control programs that rely on rodenticides alone to control and manage rodent problems aren’t effective or sustainable.  Sound rodent control management is only achieved by:

  • Reducing food and water supply
  • Reducing shelter
  • Ongoing monitoring and surveillance

These objectives can be achieved through an integrated approach made up of a number of steps that include:

  1. Prevention & hygiene
  2. Monitoring
  3. Non-chemical solutions
  4. Chemical solutions (baiting)
  5. On-going monitoring

It is essential that you use a rodenticide product that is prescribed for use in agricultural production systems (on-label use). If you use a contractor, ensure that you receive appropriate instructions for use of the product. These instructions must be strictly followed. Rodenticides should always be handled and treated with a great deal of caution as they are not only poisonous to rodents, they can also be harmful to pets, other livestock, wildlife and in sufficient doses, even humans.  When using rodenticides:

  • Read the Material Safety Data Sheet (MSDS) specific to the rodenticide you plan to use and follow all safety recommendations, including those for protective clothing outlined in the MSDS
  • Bait stations must be numbered and labelled with a ‘POISON’ sign
  • Do not eat, drink or smoke when handling baits
  • Always read the label and follow label recommendations
  • Store rodenticides in their original container: do not transfer to smaller food storage containers or something similar
  • Bait station location must be shown on a site map
  • Baits must be placed in a manner where they can be checked easily and recovered if necessary
  • Baits must not be placed where they can be accessed by children, pets, other livestock,  poultry or wildlife
  • Do not place baits anywhere where they could potentially contaminate food

Some general safety precautions should be followed in addition to those appearing on product labels. When checking on bait stations or handling baits remember to wear the appropriate safety gear specified on the label, including disposable gloves.  The use of gloves will reduce the human smell on the baits. Also remember to wash your hands and face thoroughly and change your clothes after handling used or new bait stations.

Take into account that all rodenticides are sufficiently toxic to cause death to pigs. Remember that pigs may feed on rodent carcasses. Therefore, pick up and properly dispose of any rodent carcasses that result from the use of toxic baits. Handle rodent carcasses with rubber gloves, long tongs, or shovels. Anticoagulant chemicals (which are found in the first and second generation rodenticides) are stored in the body of the rat and don’t break down in the time it takes the animal to die, so it is essential to remove any carcasses to ensure pigs don’t consume them.

Before starting a rodent control program it really pays to investigate where the signs of activity are occurring and concentrated. Burrows, runs, fresh droppings and rodent nests (made from fine shredded paper or other fibrous material) are often found in sheltered locations while insulated walls and ceilings are common nesting locations for rodents, especially mice. In pig sheds, roof rats usually build their nests in roof and wall cavities, however they can also burrow into the ground inside and outside of pig buildings. Search for evidence of rodent activity on above-ground structures, including walls, roof beams, pipes, chords, window sills, feeding systems, and rails. Rats are very good climbers and often use overhead structures to enable them to move around the piggery. When present in relatively high numbers, rats and mice occasionally can be seen during daylight hours, but they are most active at night, particularly just after dusk.

Eliminate or reduce the number of places rodents can use for shelter. Prevent clutter in and around buildings. Keep stored feed in rodent-proof facilities. Where practical, make structures rodent-proof. When rodents have no place to hide or nest, they cannot thrive.

The quality and quantity of alternative feed already available to rodents (i.e. pig feed) will influence the effectiveness of poison baits, as baits are competing with this tasty existing food for acceptance by rats. Therefore it is important that all access to alternative feed is reduced. This is very important because sufficient amounts of bait need to be eaten by the rodents for it to be effective, and appetising alternative food supplies will decrease the success of a baiting campaign. The presence of a continuous alternative food supply will lead to poor acceptance of toxic baits by rodents. Minimising rodent access to feed lines and feeding systems in general will assist greatly in rodent control as the availability of food influences their reproductive ability and population numbers.

If rodents or evidence of rodents are present, begin or increase control efforts. Use traps or rodenticides to reduce their numbers. Place baits or traps in areas where rodents are active. Maintain control efforts diligently until successful.

All pig producers are encouraged to investigate alternative rodent control options including:

  • Vitamin D3
  • Electromagnetic devices

Once rodent numbers have been reduced, continue a regular program of control to keep rodent numbers to a minimum. Maintain permanent bait stations outside sheds or traps to control invading rodents and prevent surviving rodents from breeding.

Ongoing surveillance is important to maintain control that has been achieved by a robust rodent control program.  Keep in mind that a few rodents are likely to survive even the most thorough control effort. Also, rodents from nearby paddocks or sheds may invade pig sheds at any time. These rodents will multiply quickly if not kept in check with an ongoing control program. Therefore, it is important to establish permanent bait stations in farm buildings and around their perimeter. Fresh anticoagulant bait in these stations will control invading rodents before breeding populations become established.

In summary:

  • Do not place baits in pig sheds, including in locked bait stations
    • No unsecured baits in holes in insulation or wood
    • No tracking powder, meal or pellets in sheds or bait stations immediately outside sheds
    • No paste or gel products applied to walls, beams or insulation
  • Locate bait stations between rodent nests and food supplies (outside along shed walls at ground level is appropriate)
  • Use tamper-proof or professional bait stations when using rodenticide paste, sachets and blocks
    • Secure bait to ensure that the bait is eaten within the station and cannot be removed
    • Secure bait station to fixed object with rodent proof fastening e.g. lightweight chain
  • Pick up and dispose of all rodent carcases into a designated animal-proof bin
  • Check bait stations on a regular basis and remove any old or mouldy baits
  • Dispose of all old and mouldy baits into a designated animal-proof bin
  • Do not use mice-sized baiting stations if rats are present
  • Feeders
    • Cover feeders with tight-fitting lids
    • Ensure feeder lines do not provide access to rodents
    • Check that automatic feed lines aren’t missing the access capping or the capping is not secured properly
    • Avoid feed contamination with rodent urine/faeces
  • Store bagged feed up on pallets (well above floor level) and set away from walls
  • Keep lids on silos
  • Clean up feed spills promptly
  • If feasible, ensure that sheds/rooms where feed ingredients are stored are made/remain rodent proof i.e. check these sheds or rooms often for rodent activity and damage
  • Ensure rodents do not have access to overhead feed lines and silos
  • Keep out all larger feral/wild animals from pig sheds (cats, owls, hawks)