33 minute read
ANIMAL HEALTH
Farmers will be faced with different animal health challenges as we enter the autumn and winter period. Here, we look at what farmers can do to take control of their herd’s health.
Protecting cattle from parasites
40 M. BOVIS
Good results from vaccination trial
44 DYSENTERY
Signs to look out for throughout winter
48 DISEASE
Controlling infectious bovine rhinotracheitis
To prevent costly production losses this autumn, farmers should protect their stock from parasites, says Mark Pass, a responsible animal medicines adviser at Beeston Animal Health.
He says if stock are not protected from parasites picked up during the grazing season, they will see signi cant production losses. is will come from reduced weight gain, fertility issues, irreversible lung damage, increased susceptibility to disease and possible death.
The four main parasites to be aware of include gutworms, particularly ostertagia, lungworms, fluke and lice.
Mr Pass says: “At housing, you are bringing together animals and placing them in close proximity with shared airspace, which aids disease transmission. It can also be a stressful time due to the change in housing, diet and mixing of groups. If you think about managing parasites now, it will ease the pressure on stock at housing and help ensure they are as productive as they can be.”
Parasites to look out for
Attention to parasites needs to be paid before housing commences.
GUTWORMS JType two ostertagiosis tends to occur in yearlings. The worm larvae can lie dormant (arrest) inside the youngstock until spring, when they can emerge and lead to scouring, as well as pasture contamination.
Mr Pass says it is key to use a product which will kill the inhibited larval stages. He says: “By using a moxidectin product you will cover for any arrested larvae as well as adult worms, and it is a persistent product, meaning it can be used up to five weeks before housing while the cattle are still out grazing and it will protect them.”
LUNGWORM JFailure to treat lungworm can result in quite rapid death from when signs first appear, says Mr Pass.
Even when it is picked up quickly it can still cause irreversible lung damage, increased susceptibility to pneumonia, decreased milk production and death.
FLUKE JFluke can also significantly limit production and can predispose cattle to clostridial disease.
Due to the incidence of fluke being farm-specific, Mr Pass recommends all farmers test their stock before treating.
He says: “For cattle, you can conduct a coproantigen test, which will detect whether the animal has picked up fluke six weeks previously.
“What it will not tell you though is if that animal picked it up two days previously.
“So if you know your farm is at risk of fluke, it is best to treat with the most appropriate product for the life stage of the fluke they are infected with.
Mr Pass says: “It is important to use different actives to treat fluke to reduce the risk of anthelmintic resistance developing on-farm, so for example, if triclabendazole is used in autumn, then a fluke adulticide product can be used in spring before turnout.”
LICE JLice are parasites that is often forgotten and only treated for when an infestation is severe.
Mr Pass says: “Lice can cause anaemia, reduced growth as they spend less time eating and lying, as well as being a welfare concern from the intense itching. It is important when you treat lice you treat all animals housed in that space at the same time.”
Zoetis Vet Ally Anderson says animals which have had a grazing season may be at risk and if they are carrying worms, will require treatment at or before housing.
She says a product containing moxidectin and triclabendazole, such as Cydectin TriclaMox PourOn is one option. She says: “The moxidectin will treat for stomach worms as well as controlling chewing and sucking lice. The triclabendazole gives a good spectrum of activity against late immature and adult fluke.”
42 TIMING
Avoiding gaps when it comes to vaccines
46 CALF HEALTH
Keeping a lid on pneumonia problems
52 STARLINGS
How to keep them out of buildings and feed
A vaccine against mycoplasma bovis has performed well in UK trials and could be an option for herds which are affected by the disease. Hannah Park reports.
New M. bovis vaccine welcomed by industry
UK vets have welcomed a new vaccine against mycoplasma bovis (M. bovis), with 95% of those surveyed recommending its use where the disease is present.
Since 2019, the vaccine, which has been used in the US for several years, has been assessed in a case study carried out on four farms in
Scotland by Graeme Fowlie, of
Meadows Vets, Aberdeenshire, with the help of Dutch pharmaceutical rm Kernfarm.
It has since been used by more than 56 vet rms across the UK under the Veterinary Medicines
Directorate (VMD) special import scheme, with excellent results.
Of the 40 vet practices surveyed by Kernfarm, three-quarters rated the vaccine’s e cacy at 80-100% and more than 87% said they had seen reduced clinical signs and treatment required a er using it.
Mr Fowlie says: “Treatment and control of M. bovis in the UK has been challenging in the past because of the nature of M. bovis bacteria. Existing treatment options can be ine ective and control before now has been hampered by a lack of a licensed vaccine in Europe.” e case study involved four endemically infected dairy farms and 932 calves. e same calf health parameters were compared before and a er the vaccine was administered over two six-month periods, with growth rates, mortality and antimicrobial usage evaluated before and a er the vaccine was used.
Results showed vaccinated groups demonstrated a signi cant reduction in post-weaning mortality in calves aged 70-200 days old.
Mr Fowlie says: “Of the calves involved, 31 died a er weaning pre-vaccine when looking at all causes of mortality up to 200 days of age. A er vaccination, only two died during the same period.”
A signi cant reduction in antimicrobial usage to treat calf pneumonia post-vaccination was also observed.
Mr Fowlie says: “We vaccinated cows eight weeks pre-calving and then gave the o spring of those cows a booster at four weeks.
“This worked well, but it was important that other management considerations were taken into account. If M. bovis is not the only problem, then response to the vaccine will be muted. However, if addressing this issue is the final missing link to improving herd health, then adding in this treatment will get a good response.”
Until the vaccine was approved for use in the UK under the VMD
What is M. bovis?
rM. bovis is a small bacterium which does not have a cell wall, meaning antibiotic treatments such as penicillin, which work to break down the cell wall, are not effective in treating the disease rInfection with M. bovis can be clinical or subclinical – symptoms can be chronic in some animals, others will exhibit no symptoms and recover, while others may become a long-term carrier of the disease rInfection is commonly carried in the inner ear and lungs, which is then unknowingly coughed or sneezed out by animals rM. bovis has the ability to change its appearance midinfection, which impacts the immune system’s ability to fight infection and suppress many parts of the immune system
DISEASE SPREAD rM. bovis spread in an endemically infected herd can be via aerosol, colostrum or milk rCalves can be infected from a young age: in one study nasal swabs from calves and vaginal swabs from their dams found 40% were positive for M. bovis at four days of age, suggesting possible pre- or peri-partum infection rMovement of carrier cattle is the most common way infection is spread from farm to farm
SYMPTOMS rInfection can cause pneumonia in any age animal, joint-ill in young calves or mastitis in dairy cows most commonly; less commonly it might lead to meningitis, caesar wound seromas, keratoconjunctivitis and subfertility rInfection supresses the immune system, which can then trigger other easier to diagnose infections to take hold alongside it, which is why M. bovis is hugely under-diagnosed
TREATMENT rResponse to treatment is unreliable as there is only a small number of drugs which work effectively against it rIncreasing antimicrobial resistance patterns are hampering the effectiveness of remaining drugs which work against it
GRAEME FOWLIE
Treatment and control of M. bovis in the UK is challenging because of the nature of M. bovis bacteria.
special import scheme, using autogenous vaccines, those made speci cally from the bacteria isolated on a farm, had been the only option for a ected herds.
But the cost and time involved in doing so has put many producers o .
Mr Fowlie says: “It is ge ing more expensive every year and, as a result, it is becoming increasingly inaccessible for many producers, especially those with less than a 500- to 1,000-dose requirement per annum and for units buying in a lot of ca le, like many of our clients here in Aberdeenshire who buy-in store ca le to nish in di erent batches.
“Autogenous mycoplasma vaccines are o en based on a single strain recovered from a previous pneumonia outbreak.
“ is new vaccine has three strains of mycoplasma.
“For units buying in di erent batches there may be an advantage in having a broader range of protection o ered year-on-year.”
rFarmers or vets who suspect or know they have mycoplasma in their own herd or those of their clients can get advice on potential application of any vaccination protocol from Graeme Fowlie at thevets@meadowsvets. co.uk, or 01651 872 481.
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Bringing cattle in for housing can often coincide with vaccinations being administered, but it is important to ensure these vaccinations are correctly timed. Angela Calvert reports.
The realisation some clients were allowing their vaccination programmes to slip led veterinary surgeon, Laura Donovan, of Nantwich Farm Vets, to put measures in place to tighten up the system.
She says: “If you are going to vaccinate it is important to do it properly for it to be fully e ective.
“From the practice vaccination reminder system, it became apparent that, for example, in some cases vaccines which should have been given annually were slipping to 14 months.
“ is breakdown in biosecurity leaves the door ajar for infection and in some cases can have implications for disease-free status.
“ e timing of vaccination is not as much of a problem for spring and autumn block calving herds, but if you are having calves born all-year-round, it becomes more complicated, as it is more di cult to keep track of what has been vaccinated and when, and some animals may slip through the net.
Main groups
“It is o en easy to vaccinate the main groups which are close to home, but if, for example, heifers are being grazed elsewhere, it can be easy for the timing of their vaccinations to be delayed or missed.
“It is therefore important to have a system in place with timely reminders so you can plan ahead and make sure no targets are missed.” e main diseases dairy ca le are vaccinated against are bovine viral diarrhea (BVD), leptospirosis and lungworm, traditionally done in spring as they are more likely to be contracted at grazing. en infectious bovine rhinotracheitis (IBR) at housing when respiratory disease is more likely, and sometimes salmonella.
Mrs Donovan says: “One of the key vaccinations at this time of year is for IBR and while many cows are housed all-year-round, even on these farms, other ca le, such as low yielders, are likely to be coming inside.
“ is means there will be more ca le in the same air space, so they will need protecting against IBR.”
Mrs Donovan says heifers are required to be vaccinated for BVD before their rst pregnancy and, if you are only vaccinating all stock down to six months old annually, by the time the next date comes around, some heifers could be well over 12 months old and are likely to already be in-calf. is leaves them open to infection in early pregnancy and could create a persistently infected (PI) calf.
She says: “When we have been investigating PI calves born on-farm we o en nd it is because of a vaccination gap, as a result of a group of heifers being missed.
“ is gap in protection and then a break in biosecurity as a result of something as simple as being nose to nose with a neighbour’s ca le over a fence can allow BVD into a herd.
Do not let vaccination timings slip
Chart: Sample all-year-round calving dairy herd
Timing of vaccinations is vital to ensure stock are not exposed to disease such as BVD.
“If you are part of the BVDFree scheme and use the heifer check testing method to retain BVDFree test negative status, they will need to be blood tested to check for BVD antibodies, from nine to 18 months old, but before they have been vaccinated. is is another factor which needs to be taken into consideration when planning timing of vaccinations.” e measures the practice is pu ing in place include creating a bespoke vaccination programme for each client which is recreated on a large, clearly coloured wheel chart of the year outlining which vaccine needs to be administered and when. is can then be displayed in the farm o ce where it can be seen and discussed by the whole team and can play a role in sta training.
Mrs Donovan says: “Having something visual and easy to understand really helps. Of course, farmers have to be fully on board with the process, but it is all about opening up communication and working with them to ensure the correct protocols are in place and then carried out.
“We also provide the farmer with fact sheets outlining each disease and which products are available to vaccinate for each one.
“ is can then lead to discussions about which diseases are being vaccinated for, why a particular product is being used in preference to another and if there are other emerging diseases which may need to be investigated.
Wheel
“ e wheel can be looked at and cha ed about during the course of routine visits, which helps with planning ahead, making sure nothing gets missed, and can o en be scheduled in with other tasks, saving both time and money.”
LAURA DONOVAN
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Winter dysentery is an uncommon but highly infectious viral disease in dairy cows which is hard to detect. As the name suggests, we are entering the high risk period. Wendy Short reports.
Winter dysentery difficult to diagnose
Winter dysentery is a form of bovine coronavirus, with symptoms including profuse, watery diarrhoea, dark brown in colour and sometimes containing blood, says Rob Hall of LLM Vets.
Mr Hall says the milk yields of infected cows will show a rapid decline and infected animals may also show signs of respiratory distress.
He explains that most cows a ected by winter dysentery will display symptoms for between two and seven days. e disease will usually spread through the entire herd within two weeks, having been passed on via infected faeces.
It is also thought it can be transmi ed via respiratory aerosol. e majority of infected animals will recover, with losses estimated at less than 2% and most cows recovering within a week, he says.
However, in the most extreme cases, death may occur due to dehydration and metabolic acidosis.
Some herds in the USA have reported the milk yield losses can be prolonged and animals will show signs of anorexia and struggle to regain their body condition scores. e disease has a seasonal bias, says Mr Hall. He says: “Outbreaks are mainly detected at the point of autumn and winter housing, when the cows are in closer proximity and have been subject to a dietary change,” he says.
“ e poorer ventilation in a building and the presence of other harmful micro-organisms may also be relevant factors.
“ ere is also increased risk in winter because the coronavirus survives best in colder conditions and where there is a low level of UV light.” e pathogen has a poor level of sensitivity and it is not uncommon for faeces testing via ELISA or PCR to produce a false negative result, he comments.
Due to these di culties, there have been only 17 con rmed cases in mainland Britain over the past seven years, although the actual number may be much higher.
“Diagnosis is usually based on the clinical signs alone,” Mr Hall says.
“Blood testing which reveals rising antibody levels from the point of the outbreak until some three or four weeks later can also be suggestive that bovine coronavirus is the cause.” e symptoms of winter dysentery can be confused with salmonella and a misdiagnosis can pose a serious threat to herd health, as undiagnosed salmonellosis can lead to diarrhoea, abortion and other associated illnesses.
It will o en require antibiotic treatment and e ective vaccination is available, whereas the winter dysentery virus is unresponsive to antibiotics.
Digestive upsets and possible poisoning may also be under consideration when a vet has been called in a er cows display acute diarrhoea, but in these instances dietary correction will usually resolve the problem, he adds.
Risk
e bovine viral diarrhoea virus can present similar symptoms to the Schmallenberg virus, a disease which may pose a greater risk this year.
“We are on high alert for Schmallenberg,” he says.
“It occurs in approximately four-year cycles and the UK saw outbreaks in 2012/13 and again in 2017/18.
“Infected ca le develop an immunity which will wane a er about four years and by this period, new animals which have not been exposed to Schmallenberg and have naivety to the disease will have been introduced into the herd. ere is funding for surveillance testing through the Animal and Plant Health Agency where cases are suspected.”
Recovery from winter dysentery is usually spontaneous and treatment tends to be supportive.
It will involve free access to water and possibly the administration of oral rehydration solutions. It is also recommended that diets are checked, to ensure they contain adequate mineral levels.
Severely a ected animals can also be given non-steroidal anti-in ammatory drugs and intravenous uids. ere is li le that dairy farmers can do to reduce the risk of a winter dysentery outbreak, he says.
“ e best option is to adopt a routine two-to-four week isolation period for new animals,” Mr Hall adds.
“Visitors should wear clean and disinfected footwear and overalls and it is essential to prevent disease transfer to other classes of stock.
“ ere is no licensed vaccine for winter dysentery and even if one were developed, it would be ine ective in the face of an outbreak.
“Nevertheless, there is anecdotal evidence that cows which have been vaccinated to boost antibody levels against coronavirus calf scours in their colostrum will display less acute symptoms and recover more rapidly.”
Rob Hall Outbreaks of winter dysentery are mainly detected at the point of autumn and winter housing.
Calf pneumonia is still one of the most common causes of ill health and losses, despite improvements in colostrum management and a wide range of vaccine options. Wendy Short speaks to a vet to get some tips on control and prevention.
Protecting calves from pneumonia
Calf pneumonia occurs as the result of what vet Colin Mason describes as a ‘pathogen soup,’ which is made up of bacteria, viruses and mycoplasmas.
Mr Mason, veterinary centre management at Scotland’s Rural College, says these have a permanent presence in the calf house and elsewhere on the unit in di erent combinations, with infection triggered by a range of conditions which cause stress in the animal. e main risk factor is linked
to low volume colostrum intake, poor colostrum quality and/or a delay in the rst feeding, he says.
Other risk factors include calves incorrect ambient temperature, insu cient ventilation, inadequate nutrition and stress caused by moving and mixing groups.
Producers have made great strides in colostrum management, but there is still room for improvement, says Mr Mason.
“ e colostral antibodies ingested by the calf in its initial six hours of life have a close relationship with its susceptibility to pneumonia,” he says.
“Particular a ention should be paid to calves which have been compromised at birth following a delayed or protracted calving.
“ ese animals will need extra care as they are the most vulnerable. A weaker calf may not always absorb su cient antibodies and its general state of poor health will place stress on its system. is can trigger pneumonia, or any other disease, and lead to an infection outbreak.”
Mr Mason adds that colostrum management hygiene is key.
“Colostrum must be handled using the same standards that are applied to food for human consumption. No one system is be er than another for handling colostrum and it is mainly down to a ention to detail by the operator,” says Mr Mason.
“If pneumonia is an issue, it is worth discussing the colostrum handling protocol with your vet, and there may be bene ts to be gained from colostrum pasteurisation.
“ e correct management of colostrum has a supportive role and will maximise the potential for any future vaccination programme to produce a successful result. In addition, some calves may contract pneumonia before they have reached the minimum age for vaccination.”
Tailored
Pneumonia vaccines must be administered at the right time, with products tailored to individual farms and instructions strictly followed, he adds. e highest risk period occurs within the rst eight weeks of life for milk-fed calves.
Any factor which causes bodily stress can lead to a pneumonia outbreak and a spike in case numbers was reported during the very high temperatures in July and August this year. e cold, damp weather in autumn and winter can also increase the incidence of infection.
“ e harmful pathogens thrive in these circumstances and infection can spread rapidly across the calf shed,” says Mr Mason.
“It is not easy to maintain conditions which are draught-free and well-ventilated, while at the same time keeping calves warm. Calf jackets are bene cial, but only as long as they are kept clean. It is advisable to wash and disinfect jackets regularly, particularly when they are being transferred from one calf to another.
“Moisture levels in the building should be kept to a minimum, so it is not advisable to use copious amounts of water if some pens are being cleaned out while the unit is stocked.
“ e bedding must be kept dry and a good overall standard of pen cleanliness will help with the prevention of a range of diseases, including pneumonia.”
He says a high stocking rate can exacerbate the risk of pneumonia and calves should not share the same air space as older animals.
“ e age range should be kept as tight as possible and each pen should contain calves that are no
Bedding must be kept dry and a good overall standard of pen cleanliness will help with the prevention of a range of diseases, including pneumonia.
more than a couple of weeks apart in birth date,” adds Mr Mason.
“A calf group containing animals of between one week and eight weeks old is at high risk of disease development and transmission. Ideally, an ‘all-in, all-out’ system should be adopted, although this is not always achievable in practical terms.”
Producers have become adept at checking for signs of disease, but it is always not easy to spot sub-clinical pneumonia cases, he says.
Auto-feeder
“Technology has advanced and activity meters are available, along with auto-feeder systems that will provide an alert in cases where the milk intake has dropped sharply. Otherwise, a calf with early-stage pneumonia may lie down for longer than its peers, or be slower to feed. A quick check of body temperature will usually con rm whether or not there is cause for concern.”
Pneumonia is generally considered an airborne disease, with the most frequent transmission occurring when an infected calf coughs and a second animal in close proximity breathes in the contaminated air, says Mr Mason. It can also be transmi ed via physical means, such as the nasal discharge of an infected calf coming into contact with its pen mate, for example.
Most viral pathogens have a poor survival rate without access to a host, but they are sensitive to exposure to UV light, while bacteria are more resistant to UV light and will usually persist for longer periods in the calf house. It is dif cult to allocate a precise gure to the survival rate of pathogens, as a lot will depend on the environmental conditions.
Mr Mason adds: “ e good news is that most respiratory pathogens, including the majority of strains of pneumonia, are destroyed when they come into contact with disinfectants that are designed for the purpose.
“Equipment like buckets, teat feeders and auto-feeders should be disinfected on a regular basis, but there is li le that producers can do on a day-to-day level to prevent transmission between calves through shared feeding systems.”
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The R number identifies the potential for an infectious disease to spread, but can be massively influenced by management practices. Dairy Farmer talks to MSD Animal Health’s Dr Paul Williams to discuss how it can be reduced as part of a control strategy for IBR.
Driving down the R number to control infectious disease
The world is now all too aware of the importance of the R number: a gure which identi es the potential for an infection to spread, sometimes referred to as the reproduction rate.
De ned more speci cally as the average number of secondary cases generated by one primary case of that disease, R has become an important parameter in monitoring and controlling many infectious diseases. e route of infection impacts the R number, particularly if it is an airborne virus.
R can be used to measure the risk and impact of infectious bovine rhinotracheitis (IBR), since it is spread from animal to animal, and an important route for its transmission is through nasal and respiratory discharges.
Various studies have sought to assign an R value to IBR and gures as high as seven have been calculated. However, the gure is not static, being highly in uenced by environmental factors and management practices, which are designed to reduce R to less than one.
Dr Paul Williams, MSD Animal Health’s technical manager for ruminants, says: “When R is less than one, the infection will die out over the long-term.
“And while the UK may not have eradication as its national herd goal, there are overwhelming arguments in favour of driving down the spread of the disease through the use of vaccination and biosecurity.”
Dr Williams explains if the R number is three, the disease grows exponentially.
“ e initial animal passes the infection on to three others; the three pass on to nine; the nine pass on to 27, and you can see how quickly it spreads.”
In fact, it is estimated the virus which causes IBR, the bovine herpesvirus type 1 (BoHV-1), is present in more than 70% of UK herds. is indicates just how e ective the virus has been in transmi ing from animal to animal.
However, of greater concern still are its e ects on the animal, which pull down performance and hit farm nances, even when its presence is low.
Even subclinical infection has been estimated to cost £200/cow/year in lost income due to milk loss – a loss which is brought about by a range of health problems.
Dr Williams says: “ e virus is primarily a respiratory disorder, but it also causes reduced fertility. Once infection has occurred, IBR establishes a lifelong latent infection in individuals, which can be reactivated, and is spread at times of stress.” is leaves an overall picture
IBR is primarily a respiratory disorder, but it also causes reduced fertility.
Vaccination is considered to be a priority, as even in an infected herd, a large proportion of its animals are likely to be naive.
of damage and nancial drain which costs the farming industry up to £36 million each year.
Dr Williams says: “ e e ects of BoHV-1 are particularly damaging in a naive herd su ering exposure to the virus for the rst time.”
All of this means a vaccination programme supported by a robust biosecurity policy should be the line of defence for naive herds.
Dr Williams says: “If you and your vet nd you do not have IBR, the best approach is to stop it coming in. is involves all the usual external biosecurity procedures, such as double fencing, quarantining animals on arrival and testing them a er quarantine, before they enter the herd.
“Alongside this, a vaccination programme, if not already in place, will mitigate the risks if it does enter the farm. Vaccination will reduce transmission and therefore help to bring the R number down and reduce its spread within that herd.”
However, most UK herds already have a presence of BoHV-1, and these are advised to vaccinate at the earliest opportunity.
He says: “For these herds, the goal may either be to eliminate or more likely to bring IBR under control.
“In either case, vaccination is considered a priority, as even in an infected herd, a large proportion of its animals are likely to be naive. is is because of the latent nature of the IBR infection, as carrier animals do not shed the virus all of the time.
“It could be the herd had its last shedding period two or three years ago, and in that period, a lot of new heifers have come into the herd.
Sub-population
“ is sub-population is e ectively naive, so they need protection through vaccination before joining the herd.
“Without this protection it would spread quickly within this group, which would su er the losses associated with IBR, before you were aware of what had happened.”
Ongoing monitoring
JMonitoring IBR is an important process in any herd and will identify new infection as well as latent infected animals.
Dr Williams says: “If you only have one or two latent infected animals, you may be able to cull, but this is not feasible if 30% of the herd is infected.
“That is when you would need to have a strategy of vaccination and monitoring to bring the disease under control. Latent carriers of IBR are the ‘pilot light’ for infection and newly infected animals are the main virus shedders.
“It is possible to eradicate the disease if that is your goal, as long as you maintain internal and external biosecurity and do not bring-in infected animals.”
While bringing down infection, he says think about the stress points which may cause reactivation from latency and previously infected animals to shed the virus.
Biosecurity
He says: “This may mean better biosecurity around calving, such as more calving boxes, longer isolation and better cleaning, and making sure all buildings are well ventilated.
“Eradication of IBR may not be a goal on every farm, but all herds should be driving the R number down, controlling its spread within the herd and reducing its impact on animal health and the farm’s bottom line.”
With an increased starling population as winter sets in, we round up some of the advice on how to effectively control starling numbers. Hannah Park reports.
Keeping starlings at bay
Among other challenges, winter brings with it an increase in starling numbers across the UK with migratory starlings liable for what can be huge increases in bird numbers on some dairy farms.
While effective starling control is likely to differ from farm to farm, combining several control methods is likely to be the most effective way of reducing starling numbers on-farm, says Dr Cate Williams, of Aberystwyth University.
Dr Williams says: “Starlings and other scavenging birds, such as sparrows, pigeons and doves, are well known for their partiality to total mixed rations [TMRs]. With all of these species protected by law, challenges arise in winter when native UK bird populations are joined by migratory bird flocks.
“In summer these return to their native country while domestic starlings disperse to higher land to breed. In addition to the fact that livestock are less likely to be fed a TMR in summer, the problem becomes dormant again.”
As well as depredating TMRs and other hard feed, starlings can also spread disease, says Dr Williams.
She says: “Starlings do not roost and forage at the same location and will move between several feeding sites, making them an ideal vector to disseminate pathogens. It has been confirmed that European starlings are capable of transmitting E. coli, Salmonella and campylobacter, as well as the causative organism of Johne’s disease.”
Birds may also be staying in the UK longer as a result of changing weather patterns.
Dr Williams says: “A 2012 report by Kingshay reported an extended migratory period, during which some birds remained in the UK for more than a month longer than usual due to an unseasonal cold spring.
“This resulted in a longer period in which starlings were able to predate upon cattle feed, equating to larger losses for the farmer.”
The same Kingshay report also highlights the numbers of birds making the annual migration can depend on the severity of winter conditions in central and northern Europe.
Dr Williams says physical barriers combined with other deterrents had been proven as most effective for starling control.
More recently, research which looked into feed particle size suggested feeding a pellet above a certain size was more likely to deter starlings as they were less likely to be able to eat it.
Dr Williams says: “Feeding cattle pellets 1.27cm diameter or larger was effective at preventing starling consumption on a farm in Kansas, USA.
“Feed consumed by birds reduced with an increased pellet size of 1.272.22cm resulted in consumption of just 4% of the offered ration, while pellets 0.39-0.55cm suffered 50-54% depredation. The study suggests that optimum particle size is 0.95cm in diameter and smaller, as starlings were able to consume only 11% of the offered feed, with depredation reducing with pellet size.”
Dr Williams adds that preventing consumption may even encourage starlings to leave the farm altogether in search of alternative feeding sites providing a long-term solution.
Approach
Changing feed times is another straightforward but effective approach, she says, as starlings generally feed twice a day, morning and night.
She says: “Feeding in the afternoon after the starling’s early morning feeding period is finished provides cows with an uncontaminated and complete ration. Feeding twice a day can also reduce depredation and faecal contamination for the same reasons.”
Up to now, netting or covers over feed storage has been rated the most effective bird deterrent, especially when it is well maintained. Audio and visual deterrents, such as gas guns and scarecrows, might also be effective in the short-term.
Dr William says: “Auditory techniques were determined to be relatively effective, but there was a risk of birds becoming accustomed to the deterrent. It is therefore recommended that frequent changes in device location and sounds are essential.
“The most effective was found to be species-specific alarm and distress call, however these systems may prompt noise complaints where farms are close to residential areas.
“Similarly, the use of gas guns and shooting to scare often result in complaints of noise nuisance in residential areas. Gas guns and other pyrotechnic methods can be costly to deploy and maintain, and although these methods are moderately effective, in the longterm habituation has been seen.
“It should be noted that pyrotechnics are suitable only for use on croplands as the noise can cause stress to livestock.”
Visual techniques also vary in efficacy but are most effective when applied in conjunction with auditory methods. Habituation to decoy objects, such as statues of predatory birds or scarecrows, is rapid and common.
“Live decoys, such as dogs and human scarers, are more effective, but are labour-intensive and costly.”
Starlings and other scavenging birds are well known for their partiality to total mixed rations
As well as depredating total mixed rations and other hard feed, starlings can also spread disease.
rTo find out more about preventing birds feeding on TMRs, visit businesswales.gov. wales/farmingconnect/newsand-events/technical-articles
