Autumn sales are upon us and with that, increased movement of livestock to and from the farm. Buying in livestock is something that has to happen on many farms, especially trading systems. There is a significant biosecurity risk that comes with buying in livestock.
Having a closed herd policy is one of the best ways to avoid a new disease outbreak on the farm but it can be difficult to achieve such a policy in full. Suckler and breeding sheep farms have the opportunity to limit the amount of livestock bought in annually by breeding replacements in-house. However, even on these farms, a bull or a ram may need to be purchased in.
Where a closed herd policy is not going to be a runner on your farm, the only other option available is to be mindful of the risks and have a clear procedure in place for dealing with bought-in livestock. Different types of stock will present different challenges and disease risks.
By having some knowledge of the risks, we should have a better understanding of how to avoid issues occurring. It might be a good idea to contact your local vet about disease prevention strategies for the type of livestock you are buying in.
A quarantine period of at least three or four weeks will allow routine tests and health treatments to be administered while also giving a good timeframe to identify issues.
We have outlined some of the common diseases that affect different groups of livestock and ways to prevent these diseases from happening.
In-calf heifers and replacement calves
When buying in any type of livestock, the first thing you should carry out is a visual assessment. It sounds very simple but it is surprising how this step can be overlooked at times. If the animal is coughing, has a low body condition score or is showing signs of lameness, alarm bells should be ringing. In dairy herds, a highly infectious disease such as mortellaro could be bought in, which could spread to other animals in the herd, resulting in a lameness outbreak. A history of the herd you are buying in from can help too if, for example, TB has been an issue in the area or on the source farm itself.
Infectious bovine rhinotracheitis (IBR) should be on the radar, especially when buying in young heifers. It is a viral disease and infected animals can develop loud breathing and sometimes coughing, high temperature, nasal discharge, runny eyes, weight loss, etc. Once an animal is infected, it becomes a lifelong carrier and can shed the virus when subjected to stress in some way.
The source of new infection is most commonly through the purchase of infected animals. Prevention of this disease involves avoiding mixing different age groups of stock, ensuring adequate ventilation in winter housing and avoiding stressful procedures at housing time. If you are very serious about preventing the disease entering your herd, bought-in animals can be blood-tested. All incoming stock should be blood-tested to check for IBR status on arrival, isolated for four weeks and blood-tested again. In a situation where the disease has already entered the herd, vaccination is the only feasible option. There are both live and inactivated IBR vaccines available. The differences between the two are:
The live IBR vaccine is better to use in the face of clinical disease so it should be used when you have a problem.
The inactivated IBR vaccine is better at reducing shedding from carrier animals, so it should be used when the problem is under control and an eradication plan is in place.
Farmers should be aware of the threat of bovine viral diarrhoea (BVD) disease when buying in in-calf and breeding livestock. Contrary to the name, BVD rarely causes diarrhoea. The most common manifestation of the disease is that of immunosuppression.
In pregnant cows and heifers infected in the first two months of pregnancy, BVD leads to early embryonic deaths and problems with cows repeating. The disease can also lead to cows and heifers aborting during mid-gestation onwards. High levels of exposure to the virus, shed by persistently infected animals can lead to increased calf disease in the form of diarrhoea and pneumonia.
Knowing the source herd’s BVD status will help you plan how to approach the disease. Try to find out if the source herd was vaccinated for the virus. If the herdowner did not vaccinate and you do, it may be dangerous to introduce unvaccinated heifers naïve to the disease to your herd. If there were issues with BVD in your herd in the past, vaccination could play a role. Ideally, vaccination programmes should be completed a month before the breeding season starts. If it is left too late, adequate protection cannot be guaranteed.
To avoid problems in the future, all persistently infected animals should be removed from the herd. If heifers are purchased in-calf and the BVD status of the foetus is unknown, the animals should be isolated at birth until the BVD status is known.
Mycoplasma bovis has been in the news a lot lately because of its spread in New Zealand and the measures it is taking to control the problem.
The disease can manifest as respiratory problems occurring in purchased weanlings, mastitis and arthritis-type problems in milking cows and ear infections or pneumonia occurring in young calves. There is no vaccine available for this disease.
The main way farmers can prevent its introduction is by taking normal biosecurity measures when buying in livestock. Where it has been a problem on your farm already, it is important to clean the environment, especially drinking points.
The sudden death of newly purchased animals can cause a shock and is frustrating. A lot of the time, this can be the result of clostridial diseases such as blackleg. As there is a wide variety of clostridial diseases out there, a multivalent vaccine which covers several types of clostridial disease should be used to prevent issues.
Leptospirosis is a disease that no one wants to see in either suckler or dairy herds. It can manifest as abortion or infertility and sometimes milk drop syndrome, mastitis or weak calf syndrome. It is much more common in larger herds so be aware of that when making purchasing decisions.
Infection in cattle is acquired from contact with infected urine and the products of abortion including foetuses, cleanings and discharges. Again, good biosecurity measures are important to prevent disease spread.
Vaccination plays an important role in the control of leptospirosis but like BVD vaccination, it should be carried out a month before breeding. Other abortion-causing diseases such as salmonella and neosporosis should be taken into consideration when making purchasing decisions. Ask the source farmer if they had issues with these diseases in the past.
Another disease that can cause problems for herds is Johne’s. It can lead to weight loss, diarrhoea and eventual death. Unfortunately, the disease is very difficult to identify in the initial stages, even by using diagnostic tests. It is only when the disease progresses that clinical signs may become apparent.
A whole herd test should be carried out to identify at-risk animals. If your herd currently tests negative for Johne’s disease, a good biosecurity and purchasing policy is essential.
Try to buy from low-risk herds if animals need to be bought in.
Other preventative measures include avoiding the importation of slurry and colostrum.
When buying in beef weanlings, look out for obvious signs of issues such as coughing, drooping ears, discharge from the nose and sweating. Animals that are not fully weaned should be avoided.
The main risk farmers need to be conscious of when buying in beef weanlings is respiratory disease. Check for obvious signs of issues such as coughing, drooping ears, discharge from the nose and sweating.
Avoid buying animals that have not been fully weaned. If an animal is bawling and unsettled, they are more likely to develop issues such as pneumonia. Lungworm is common in weanlings with the main symptoms being coughing and shallow breeding.
Bought-in weanlings should continue to receive regular worm treatments on the advice of your vet. Try to time worm treatments, so that they do not clash with other stressors such as weaning or castration.
Pneumonia is very common in young stock and weanlings are particularly susceptible. The cause of pneumonia can be attributed to viruses such as IBR, RSV and PI3, bacteria such as mycoplasma bovis or parasites such as lungworms. There are effective vaccines available against IBR, RSV and PI3. These vaccines can be divided into intranasal vaccines and injectable vaccines. The intranasal vaccines stimulate good immunity in a very short period of time (three to seven days) and are suitable for use in the face of an outbreak of pneumonia. However, this is a relatively short acting vaccination.
On the other hand, injectable vaccines may take three to four weeks to stimulate maximal immunity, but they are longer-lasting. No vaccine gives 100% protection and disease prevention still relies on good management of housed livestock (adequate ventilation and optimum indoor stocking rates).
Beef weanlings should also receive a clostridial vaccine on purchase, which covers several clostridial diseases to avoid sudden deaths occurring (as mentioned previously).
Breeding ewes and hoggets
Newly-purchased breeding sheep should be held in quarantine for 30 days to help identify any diseases early and prevent them from spreading to the main flock.
A visual and physical assessment of breeding ewes, hoggets and rams will pay dividends because there are a lot of issues that can be picked up at this stage. Check if the sheep are walking lame. If a number of sheep in the group are lame, you should avoid purchasing the animals. If just one sheep is lame, her foot should be assessed – it might be just a stone causing the pain, for example. However, if it looks like an infectious agent you may want to reconsider your options.
The two main lameness diseases that are difficult to control once they enter a flock include infectious footrot and contagious, ovine, digital, dermatitis (CODD). Footrot is most common and flocks should aim to have less than 5% infected. Segregation of infected sheep is vital. It can be treated successfully with antibiotics and there is also a vaccine available.
CODD is a very severe clinical condition and can spread through a flock quickly. Biosecurity is crucial in its prevention and control. Ideally, sheep should only be purchased from flocks free of the disease. Before purchased animals are introduced into the flock, they should be held in quarantine for 30 days to allow clinical signs to develop if the disease is present. If you suspect a case of CODD in your flock, it is highly recommended that you call your vet before it gets established.
Mouths should be looked at to ensure ewes are not missing teeth or suffering from an over-shot or under-shot jaw. The udder should be handled to check for swelling/lumps or missing teats.
Diseases that cause abortion in sheep, such as enzootic abortion and toxoplasmosis, can be horrific if they enter your flock. In the case of enzootic abortion, if buying in replacement sheep from an unknown health status flock you should consider vaccination. If your flock has suffered from the disease in the past, replacement sheep should be vaccinated. Ideally, replacements should be bred from within the flock.
Toxoplasmosis is the main cause of abortion in sheep in Ireland. Unlike enzootic abortion it cannot spread from sheep to sheep as the disease is spread by cats shedding oocysts on animal feed. Where toxoplasmosis has been confirmed or there is a history of it on the farm and naïve animals are being introduced, veterinary advice is to vaccinate these animals.
Autumn sales are upon us and with that, increased movement of livestock to and from the farm. Buying in livestock is something that has to happen on many farms, especially trading systems. There is a significant biosecurity risk that comes with buying in livestock.
Having a closed herd policy is one of the best ways to avoid a new disease outbreak on the farm but it can be difficult to achieve such a policy in full. Suckler and breeding sheep farms have the opportunity to limit the amount of livestock bought in annually by breeding replacements in-house. However, even on these farms, a bull or a ram may need to be purchased in.
Where a closed herd policy is not going to be a runner on your farm, the only other option available is to be mindful of the risks and have a clear procedure in place for dealing with bought-in livestock. Different types of stock will present different challenges and disease risks.
By having some knowledge of the risks, we should have a better understanding of how to avoid issues occurring. It might be a good idea to contact your local vet about disease prevention strategies for the type of livestock you are buying in.
A quarantine period of at least three or four weeks will allow routine tests and health treatments to be administered while also giving a good timeframe to identify issues.
We have outlined some of the common diseases that affect different groups of livestock and ways to prevent these diseases from happening.
In-calf heifers and replacement calves
When buying in any type of livestock, the first thing you should carry out is a visual assessment. It sounds very simple but it is surprising how this step can be overlooked at times. If the animal is coughing, has a low body condition score or is showing signs of lameness, alarm bells should be ringing. In dairy herds, a highly infectious disease such as mortellaro could be bought in, which could spread to other animals in the herd, resulting in a lameness outbreak. A history of the herd you are buying in from can help too if, for example, TB has been an issue in the area or on the source farm itself.
Infectious bovine rhinotracheitis (IBR) should be on the radar, especially when buying in young heifers. It is a viral disease and infected animals can develop loud breathing and sometimes coughing, high temperature, nasal discharge, runny eyes, weight loss, etc. Once an animal is infected, it becomes a lifelong carrier and can shed the virus when subjected to stress in some way.
The source of new infection is most commonly through the purchase of infected animals. Prevention of this disease involves avoiding mixing different age groups of stock, ensuring adequate ventilation in winter housing and avoiding stressful procedures at housing time. If you are very serious about preventing the disease entering your herd, bought-in animals can be blood-tested. All incoming stock should be blood-tested to check for IBR status on arrival, isolated for four weeks and blood-tested again. In a situation where the disease has already entered the herd, vaccination is the only feasible option. There are both live and inactivated IBR vaccines available. The differences between the two are:
The live IBR vaccine is better to use in the face of clinical disease so it should be used when you have a problem.
The inactivated IBR vaccine is better at reducing shedding from carrier animals, so it should be used when the problem is under control and an eradication plan is in place.
Farmers should be aware of the threat of bovine viral diarrhoea (BVD) disease when buying in in-calf and breeding livestock. Contrary to the name, BVD rarely causes diarrhoea. The most common manifestation of the disease is that of immunosuppression.
In pregnant cows and heifers infected in the first two months of pregnancy, BVD leads to early embryonic deaths and problems with cows repeating. The disease can also lead to cows and heifers aborting during mid-gestation onwards. High levels of exposure to the virus, shed by persistently infected animals can lead to increased calf disease in the form of diarrhoea and pneumonia.
Knowing the source herd’s BVD status will help you plan how to approach the disease. Try to find out if the source herd was vaccinated for the virus. If the herdowner did not vaccinate and you do, it may be dangerous to introduce unvaccinated heifers naïve to the disease to your herd. If there were issues with BVD in your herd in the past, vaccination could play a role. Ideally, vaccination programmes should be completed a month before the breeding season starts. If it is left too late, adequate protection cannot be guaranteed.
To avoid problems in the future, all persistently infected animals should be removed from the herd. If heifers are purchased in-calf and the BVD status of the foetus is unknown, the animals should be isolated at birth until the BVD status is known.
Mycoplasma bovis has been in the news a lot lately because of its spread in New Zealand and the measures it is taking to control the problem.
The disease can manifest as respiratory problems occurring in purchased weanlings, mastitis and arthritis-type problems in milking cows and ear infections or pneumonia occurring in young calves. There is no vaccine available for this disease.
The main way farmers can prevent its introduction is by taking normal biosecurity measures when buying in livestock. Where it has been a problem on your farm already, it is important to clean the environment, especially drinking points.
The sudden death of newly purchased animals can cause a shock and is frustrating. A lot of the time, this can be the result of clostridial diseases such as blackleg. As there is a wide variety of clostridial diseases out there, a multivalent vaccine which covers several types of clostridial disease should be used to prevent issues.
Leptospirosis is a disease that no one wants to see in either suckler or dairy herds. It can manifest as abortion or infertility and sometimes milk drop syndrome, mastitis or weak calf syndrome. It is much more common in larger herds so be aware of that when making purchasing decisions.
Infection in cattle is acquired from contact with infected urine and the products of abortion including foetuses, cleanings and discharges. Again, good biosecurity measures are important to prevent disease spread.
Vaccination plays an important role in the control of leptospirosis but like BVD vaccination, it should be carried out a month before breeding. Other abortion-causing diseases such as salmonella and neosporosis should be taken into consideration when making purchasing decisions. Ask the source farmer if they had issues with these diseases in the past.
Another disease that can cause problems for herds is Johne’s. It can lead to weight loss, diarrhoea and eventual death. Unfortunately, the disease is very difficult to identify in the initial stages, even by using diagnostic tests. It is only when the disease progresses that clinical signs may become apparent.
A whole herd test should be carried out to identify at-risk animals. If your herd currently tests negative for Johne’s disease, a good biosecurity and purchasing policy is essential.
Try to buy from low-risk herds if animals need to be bought in.
Other preventative measures include avoiding the importation of slurry and colostrum.
When buying in beef weanlings, look out for obvious signs of issues such as coughing, drooping ears, discharge from the nose and sweating. Animals that are not fully weaned should be avoided.
The main risk farmers need to be conscious of when buying in beef weanlings is respiratory disease. Check for obvious signs of issues such as coughing, drooping ears, discharge from the nose and sweating.
Avoid buying animals that have not been fully weaned. If an animal is bawling and unsettled, they are more likely to develop issues such as pneumonia. Lungworm is common in weanlings with the main symptoms being coughing and shallow breeding.
Bought-in weanlings should continue to receive regular worm treatments on the advice of your vet. Try to time worm treatments, so that they do not clash with other stressors such as weaning or castration.
Pneumonia is very common in young stock and weanlings are particularly susceptible. The cause of pneumonia can be attributed to viruses such as IBR, RSV and PI3, bacteria such as mycoplasma bovis or parasites such as lungworms. There are effective vaccines available against IBR, RSV and PI3. These vaccines can be divided into intranasal vaccines and injectable vaccines. The intranasal vaccines stimulate good immunity in a very short period of time (three to seven days) and are suitable for use in the face of an outbreak of pneumonia. However, this is a relatively short acting vaccination.
On the other hand, injectable vaccines may take three to four weeks to stimulate maximal immunity, but they are longer-lasting. No vaccine gives 100% protection and disease prevention still relies on good management of housed livestock (adequate ventilation and optimum indoor stocking rates).
Beef weanlings should also receive a clostridial vaccine on purchase, which covers several clostridial diseases to avoid sudden deaths occurring (as mentioned previously).
Breeding ewes and hoggets
Newly-purchased breeding sheep should be held in quarantine for 30 days to help identify any diseases early and prevent them from spreading to the main flock.
A visual and physical assessment of breeding ewes, hoggets and rams will pay dividends because there are a lot of issues that can be picked up at this stage. Check if the sheep are walking lame. If a number of sheep in the group are lame, you should avoid purchasing the animals. If just one sheep is lame, her foot should be assessed – it might be just a stone causing the pain, for example. However, if it looks like an infectious agent you may want to reconsider your options.
The two main lameness diseases that are difficult to control once they enter a flock include infectious footrot and contagious, ovine, digital, dermatitis (CODD). Footrot is most common and flocks should aim to have less than 5% infected. Segregation of infected sheep is vital. It can be treated successfully with antibiotics and there is also a vaccine available.
CODD is a very severe clinical condition and can spread through a flock quickly. Biosecurity is crucial in its prevention and control. Ideally, sheep should only be purchased from flocks free of the disease. Before purchased animals are introduced into the flock, they should be held in quarantine for 30 days to allow clinical signs to develop if the disease is present. If you suspect a case of CODD in your flock, it is highly recommended that you call your vet before it gets established.
Mouths should be looked at to ensure ewes are not missing teeth or suffering from an over-shot or under-shot jaw. The udder should be handled to check for swelling/lumps or missing teats.
Diseases that cause abortion in sheep, such as enzootic abortion and toxoplasmosis, can be horrific if they enter your flock. In the case of enzootic abortion, if buying in replacement sheep from an unknown health status flock you should consider vaccination. If your flock has suffered from the disease in the past, replacement sheep should be vaccinated. Ideally, replacements should be bred from within the flock.
Toxoplasmosis is the main cause of abortion in sheep in Ireland. Unlike enzootic abortion it cannot spread from sheep to sheep as the disease is spread by cats shedding oocysts on animal feed. Where toxoplasmosis has been confirmed or there is a history of it on the farm and naïve animals are being introduced, veterinary advice is to vaccinate these animals.
This is a subscriber-only article
SHARING OPTIONS: