Increased rodent activity is expected this year due to the recent usually warm and wet conditions. So how can producers reduce the risk of infestation and avoid any potential losses?
TEXT DANI HAWKINS
Harsh winter conditions typically help to control rodents, reducing their population come the spring. But with 2023 being the warmest year on record, rodent numbers have increased considerably. This, coupled with increased rainfall and flooding across the UK in late winter and early spring 2024, has seen an influx of rodents entering units and buildings from further afield in search of refuge.
Contaminated feed
“Rodents are a significant threat to biosecurity,” says BASF’s Laurence Barnard. “They spread disease – to livestock and humans – and consume and contaminate large quantities of livestock feed.”
A typical dairy unit facing a significant infestation of around 100 rodents, each weighing around 300g with a daily feed requirement of around 10% of their body weight, producers can expect to livestock feed losses of more than one tonne per year.
Contaminated feed can pose a disease risk to cattle, as can contact with rodent droppings, hair and urine.
“Rats and mice can carry upwards of 45 diseases and those that pose the most significant threat to cattle are leptospirosis, salmonellosis, neosporosis. These not only impact herd health and welfare, and result in production losses, but they also increase the risk of cows developing other diseases, such as mastitis,” says Mr Barnard.
Rodents also pose a risk to producers’ health and wellbeing. Rats and mice carry diseases that can be easily be transmitted to people, as well as livestock.
Salmonellosis, hantavirus and leptospirosis are just three of the main zoonoses transmitted by rats. These diseases can be passed on through contact with rodent droppings or bodily fluids that carry the bacteria. Proper protective equipment and good hygiene practices, such as regular and thorough hand washing, can help.
“But the most effective way to reduce the risk is to prevent rodents from gaining access to the farm or buildings in the first place,“ stresses Mr Barnard.
Health risk: rodents can spread disease and cause stress
Maintenance routine
So how can producers discourage rodents? Keeping the site clean and tidy is important. “This should be a regular and important part of unit’s maintenance routine. Keeping stacks of pallets and sacks to a minimum is important, because these make the perfect harbourage, and remove rubbish or unwanted stores of straw and hay as soon as possible. This gives rats and mice less time to move in.”
Vegetation and bushes around buildings should also be cut back and maintained. “Rats have a fear of open spaces, keeping a clear one-metre boundary around all structures will make them less inclined to cross open yards to enter buildings,” says Mr Barnard.
“This also allows producers to readily observe any rat burrows and gives natural predators more chance of spotting the pests too.”
Taking steps to rodent-proof buildings can also help to deter rats and mice. “Rodents can fit through surprisingly small openings – mice can get through gaps of 6mm, and rats can get through gaps of 10mm. So carefully inspect any buildings, stores or outhouses for wear and tear in walls, piping, doors, and windows. Use a hardwearing materials, such as metal sheeting and concrete, to prevent rodents from re-entering through any compromised areas, as rats can chew through everything from wooden posts to dry walls,” he adds.
Producers should also inspect buildings for signs of an existing infestation. Visible pawprints at ground level or on ledges, smear marks along ledges, walls or cables, damage in structures and equipment from gnaw marks, and droppings are all tell-tale signs of rodent activity.
“Also check electrical cabling. Many farm fires are caused by rodents chewing through wires.”
Feed should also be securely stored. “A lack of available feed sources will deter rats. Ensure stores are thoroughly cleaned and inspect them closely for any entry points or damage where rodents may enter. And always clean up any feed spills immediately.”
Monitoring paste
Producers should also monitor for activity, ideally using a paste, to help spot signs early and prevent infestation. Using a paste also means any rodents in the area will become more familiar with baiting objects, reducing neophobia when the monitoring product is replaced with rodenticide. “An alternative monitoring method is to leave a patch of sand along a suspected rat run overnight and look for paw marks in the sand the next day,” says Mr Barnard, adding that if activity persists, effective control is needed to quickly reduce rat numbers.
Selontra, which contains the active ingredient cholecalciferol, is a soft block bait that causes death from hypercalcaemia – the accumulation of too much calcium in the blood. This results in a stop-feeding effect, on both the bait and any available food on the site, 24 hours after consuming a lethal dose. This makes complete control possible in as few as seven days.
“Implementing a rigorous and consistent pest-management plan can help to reduce the biosecurity risk posed by rodents,” says Mr Barnard.
“Rodent-proofing buildings and maintaining elevated levels of hygiene mean that producers can decrease the likelihood of a rodent infestation occurring in the first place. The risk of disease and stress to both cattle and humans is reduced, and herd productivity and profitability are also protected.”
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