Rats contribute to the spread of diseases such as swine dysentery, they also have a major impact on feed stocks - 100 rats can eat up to one tonne of feed per year, according to the Western Australia's Department of Agriculture and Food. Managing this problem using appropriate methods will help promote herd health and reduce loss of feed.

What can be done to manage these pests?

Feed availability

Rats often live in piggeries because they have easy access to feed. Some experts advise producers to "deny access to feed” but that is easier said than done.

It is important to look at how your feed is stored and delivered to your pigs; can you prevent the spillage and store feed in sealed bins rather than loose? Are the feeders spilling feed on the ground or down the slats? Assess the feed area, determine where the rats are accessing the feed and place a physical barrier in their way, or a bait station in their path.

Baits, traps and dogs

Rats are ‘neophobic’ meaning they are afraid of anything new. Hence, they are reluctant to try the new bait you’ve put down for them, particularly if it is in a different form from their regular feed. The other reason rats will not take baits is that there is plenty of other feed available to them. Therefore, it is important to do everything possible to limit the rat’s access to feed first and then use baits.

The two types of bait are single-dose poisons and anticoagulants. The single-dose baits can be hazardous and are only available to licensed pest controllers. Anticoagulants slow the clotting ability of the blood and have to be eaten over a period of time to be effective. The rat usually dies after consuming this bait for three to 10 days. These baits are less toxic to humans and other species than the single dose baits.

Rats can develop bait avoidance behaviour but alternating between different bait types can prevent such behaivour from occurring. Baits are best provided as bait stations, such as inside a piece of poly pipe that the rat has to run through to get from point A to point B. These should be out of the reach of pigs and other animals such as dogs.

Other methods of control include shooting, trapping and the use of a dog like a Jack Russell terrier. If you do use a dog to catch rats, be careful not to use baits as well as the dog can get ill from consuming a poisoned rat.

Buildings

The ‘Plan it, Build it’ manual has some good advice on rodent proofing buildings. The manual recommends that all holes of greater than 2-cm in diameter should be sealed to stop access by rats. Gaps under doors, around walls and along feed or water pipes are all ‘doors’ for rats to enter and should be sealed.

Rats are particularly fond of nesting in insulation, however, rats are unable to nest in sealed sandwich panels and polyurethane sprayed externally. Other nesting sites, such as underneath piles of wood, corrugated iron or rubbish, under the building itself and near vegetation, should be removed or destroyed.

Rats are not all the same; there are many species of rats and each species has a preference for living in different environments. Some species prefer living in roof spaces, other below ground etc. It is important to identify what types of rats you have as you may have more than one species.

Rat being observed using motion activated cameras in a baited trap area

July 2014