Wales Farmer JANUARY 2014 HEALTHY advice


Takecontroltostop rodentstaking over


WINTER is the time of year when farms experi- ence the most problems from both rats and mice. It is logical really, the weather is colder so they move indoors to anice warm shed with aready supply of feed. In other words afarm feed store


will do nicely! While rodent infestations have


traditionallybeen controlled onlywhen they reach trouble- some levels,today’sfarmassur- ance requirements makeeffective and verifiablerodent control essential on ayear-round basis in order to avoid the rodents spreading disease,eating and contaminating feed, as well as causing serious damage to the buildings.


Rats


THE species most commonly found in Europe is known as the Norway Rat(Rattus norvegicus). Aless commonlyfound species, the black or roof rat, (Rattus rat- tus), is largelyrestricted to port areas,but they both live along- side man, invading his buildings and eating his food. Importantly rats transmit disease,which are potentiallyfatal to man such as Weil’sdisease and murine typhus. Damage by rats to the fabric


of buildings can be costly. Fires can easilybestarted after arat


In aregular column for Wales Farmer, SALLY HARMER, animal health manager for Clynderwen and Cardiganshire Farmers (CCF) highlights seasonal health management issues and solutions in the livestock sectors.


has gnawedacable.Gas and water pipes arealso at risk and ratburrowing can undermine foundations and damage water courses. Physicallyvery strong, rats


have been known to survive for twodaysinopen water,toswim amile in open sea and to get through agap of less than 25mm.


Mice


MICE carry diseases such as sal- monella and can transmit atype of Leptospirosis,but not Weil’s disease.Their continual dribble of urine contaminates food and feedstuffs and they areaparticu- lar problem in poultry units and pig housing and avery real pest in grain stores,warehouses and domestic premises.


Because mice can reach sexual


maturity 42 days after birth, populations grow much faster than those of rats,which take about twice the time to reach maturity. The difficulty of preventing


access,coupled with rapid popu- lation growth and natural disper- sal of mice,means thatalarge building maycontain anumber of colonies,each of which must be treated as aseparateinfesta- tion and control needs to be tackled systematically.


Regular


control WITH food safety in mind, the need to guardagainst contami- nation is placing growing con- straints on howand where


ANIMAL HEALTH 23


TIMING IS CRUCIAL: Rat control opportunities on atypical mixed farm. The best modern strategy


rodenticides can be used, shifting the emphasis to baiting outside buildings and better environ- mental management to prevent infestations. Repopulation of territories


cleared of rats and mice makes farmcontrol acontinuous chal- lenge and ‘fire-brigade’ treat- ment is insufficient to achieve the levelofcontrol required today.


involves an annual cycle of treat- ments at keytimes of the year when rodents aremost vulnera- bleand the system permits the safest control. The best time to use rodenticides is when thereis the least amount of alternative food available, so it makes sense thattreatment times aredesigned to fitwith the farm’sparticular annual production cycle – between batches of stock or around keyseasonal changes,for instance. Because rats thrive best in sta-


bleenvironments and become especiallywary of change,con- trol will generallybebetter when undertaken ahead of rather than during or immediatelyafter major changes.


Signs of rat


activity *Holes or burrowsinrough


ground, earth banks and unmade floors *Well-worn runs along the


sides of buildings with smear marks and hairs *Droppings at feeding sites,


around burrowsand along rat runs


*Gnawing and chewing dam-


agetomaterials and buildings *Foot prints in soft surfaces


and tail swipes in stored grain *Acharacteristic smell in enclosed areas


Good bait


management WHILE baiting in external bur- rows has been found to give the best ratcontrol, it can present greater risks to other wildlife. Whereverpossible,therefore, securebaiting containers sited betweenburrowsand nests and the main sources of food are preferable.For the greatest suc- cess the bait should be presented as close to the burrow and as dis-


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tant from alternative food sources as possible. With rats,baiting containers


should always be placed along well-travelled runs.Choose sites thatthe rats consider safe,such as alongside walls,inrecesses,at the edges of hayorstraw stacks, and in undergrowth –see the dia- gram below, left. The precise location of baiting


points is far less important with mice,the keytocontrol being a sufficient number in the general area of activity. Plenty of baiting points is


vital to ensureasmanyrodents as possible areabletoconsume a lethal dose of bait as rapidlyas possible.Failuretoreplenish bait often enough is acommon rea- son forpoor rodent control. This and the removalofbaits


beforeacomplete cessation of rodent activity all too often pre- vents the entirepopulation from consuming alethal dose. Baiting points should, ideally,


be checked and topped-up wher- evernecessary every three to four days,orsix or seventimes during atypical three to four week pro- gramme. Don’t forget to recordbaiting


activity in the recordbook. To achieve the best and safest


control of rats and mice: *Appreciate the increasing challenge posed by the compet- ing pressures of safety and grow- ing behavioural resistance. *Understand the keyele-


ments of natural rodent behav- iour thatcan best be exploited to ensurethe most rapid, complete and reliablecontrol. *Plan and implement regular,


integrated control programmes based around effective rodenti- cide baiting in sufficient, well- located and securecontainers. *Takefull advantage of mod-


ern bait technology to signifi- cantlyincrease the speed and reliability of rodenticide con- sumption.


Thank youtoBASF forpro-


viding some of the information used in this article.


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