In association with Poultec Training Ltd

Vermin will always be a concern for poultry producers, but by taking an integrated approach to control, it is possible to keep problems at bay, advise David Selway and Geraint Price from Novartis Animal Health.

Rodents and flies are two of the most common pests affecting poultry units and can be incredibly difficult to control. The biggest issue is the speed with which they multiply, meaning any delay in action can result in a massive infestation.

Rats are becoming more prevalent. One female rat can produce up to 700 young per year, each of which reaches sexual maturity at two to three months old, and will then have four to six litters of its own.

Rodents are notorious carriers of disease, with up to 30% of the population carrying leptospirosis. They can also transmit tapeworm, foot-and-mouth disease, brucellosis, listeriosis, salmonella and a range of other diseases.

To properly control rodents, you need to understand how they behave, and take an integrated management approach.

The first step is to monitor rodent activity on the unit and surrounding facilities. Rodents are most active at night, so it is best to take a torch out for a good look round.

Being very secretive by nature, every one rat seen at night indicates another 50 unseen. And every rat seen in daylight suggests 100 lurking in the undergrowth.

Other signs to look out for include dead rats, droppings, gnawed items, holes, runways, bait takes and burrows. Live or spring traps are also useful monitoring aids.

Rodents should be controlled as soon as any signs of infestation are noted. Any delay will give them time to breed and spread, making subsequent control more difficult.

Rats use set runs between the nest and food source, and prefer to stay under or near cover such as weedy, unkempt areas; stacks of pallets or rubbish; and building ledges. Typical food sources include spilt feed, organic waste, and accessible feed sacks.

General cleanliness

General cleanliness is incredibly important – if there are food sources and shelter there will be a risk of rodents. Cleaning up yards and food spills is, therefore, a very effective way to limit infestation.

Preventing access to buildings will also help, although rats will get through any hole over 1.5cm (0.6in), with mice able to squeeze through gaps of just 0.7cm (0.3in).

Once producers have identified a problem, they should draw up a treatment plan, with a map of any bait or trap sites. The best type of bait to use is one that is palatable to the rat and lethal in a normal amount of food. Anticoagulant bait types are up to 100% effective when used properly and are the most common rat bait used on farms.

The key is to choose a good quality base. Broken grains may be more palatable in the summer, but will soon break down when left out in wet conditions, so choose whole grain bases for winter use.

Mouse poisons will not be effective on rats and mice won’t eat rat bait, so be sure which animal you are targeting. Mixing mouse bait with drinking chocolate will make it more palatable.

Bait boxes should be placed along the rats’ runways (not at right angles to them), next to shelter, and every 4m (about 13ft) if there is a real problem. It is important to refill them regularly and keep them away from wildlife and children. Dead rodents should be buried or burned to remove the disease risk.

Talk to your supplier of rodenticide as they will know the best action to take. Contrary to popular belief resistance to rat bait is very low, so if bait is apparently not working it is most likely because there are more rats than expected in the area.

Common mistakes include not monitoring rodent populations, not checking traps or replenishing bait boxes frequently enough, and incorrect placing of bait boxes. Clean up the yard, be active around major food sources, and give rats a private bait place. It’s critical to take a holistic approach.

Tackling flies

The same is true when tackling flies. Fly control is a difficult and complex task, requiring an integrated approach.

The most common flies in poultry units are houseflies and lesser houseflies, which have a seven-day reproductive cycle and lay about 120 eggs a week. One pair of houseflies can produce more than one million flies a month. You can go from not having a problem to having a big problem very quickly.

Poultry sheds provide the ideal temperature and environment for flies, which not only spread disease but are a nuisance to livestock, affecting their productivity. Maggots spread through poultry manure can also cause problems for local communities.

If Environmental Health gets a complaint they have to act, and will head straight for the nearest farm.

Careful monitoring

Careful monitoring is again the first step in any control strategy. Producers should carry out fly counts twice a week between March and November, and once a week over the winter, as recently warmer winters are encouraging fly populations.

However, only 15% of flies are adult at any time, with the remaining 85% in egg, larval or pupal states (see below). If you have flies, chances are you will have a huge amount more about to arrive.

It is, therefore, important to monitor maggots in the top 10.2cm (4in) of litter, particularly on slatted floor systems, which provide ideal conditions for fly breeding – unlike broiler houses where chickens tend to feed on maggots in the litter. Flies like moist areas, so keep litter dry by avoiding spillages, collecting broken eggs and dead birds, and ensuring good ventilation.

Chemical control is usually required, but it should be in combination with other methods, and must be recorded and carried out by trained personnel. It should also be targeted, at the type of fly and stage of life cycle, including larvicides and adulticides.

Get your dose rates right or you can encourage resistance. Products with the active ingredient Pyrethoid are very effective, but have a problem with resistance, so should only be used about once a year. Residual sprays can be used on resting areas like window sills, and paint-on bait boards are very useful to hang in problem areas.

Beetles, mites, wasps and birds provide natural fly control, so it may be worth buying in parasitic wasps and choosing selective chemical products which don’t damage beneficial insects, he adds. It is also important to treat other farm facilities where flies are a concern. Find the source of the problem and sort it out as quickly as possible.