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ABOVE Alistair Mcnab, independant consultant.
LEFT Cattle should be kept in isolation with blood testing and vaccinations carried out before joining the main herd.
• IBR should high on your list, as it is becoming widespread and can cause a big drop in milk yield posing a significant risk to the economics of starting up and to the ongoing economics of your herd.
• Of the long-term diseases Johne’s is probably the most significant. Control of established disease in a herd is slow and expensive with the need to slaughter positives and their last offspring. This can lead to the loss of top genetics and long-term productivity and can impact on quotas and future supply contracts from the need to seek replacements quickly.
• Leptospirosis is an infectious disease which can cause illness, milk yield drop, abortion and can infect humans. There are Health and Safety implications to be considered here.
• Neospora can cause abortion and a blood test is available. There is no treatment or vaccine and control should be discussed with your vet.
• Viral diarrhoea and pneumonia in calves ties up scarce resources of time and labour and affects the lifetime production potential of an animal.
• Salmonella is a bacterial disease which can affect humans. Cattle which are affected can become carriers and excrete the bacteria in later life thus reinforcing the point of getting a disease profile of the herd of origin.
• Mastitis history needs to be established. Which cows have been affected, what cause was established, what treatments have been used, which were ineffective? Is there a history of antibiotic resistance?
• Parasites are a major concern in particular liver fluke as there are only limited opportunities for control in the
Control of disease needs as much time and investigation as all the other factors in setting up your herd
adult dairy cow. Mange, lice, ticks, and gutworms all need to be identified and treated.
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• Other skin problems such as ringworm and warts need to be checked.
• Digital dermatitis is of particular concern in the dairy industry and its presence in a herd can influence your purchasing decisions.
• Major emerging concerns are antibiotic and anthelmintic resistance. Enquiries should be made as to the range of antibiotics and anthelmintics used in the herd of origin and their efficacy for all diseases, not just mastitis.
One word summarises this investigation, evaluation and management process – biosecurity. Biosecurity is facilitating the security of your herd from organisms, which can have a detrimental impact on its health, welfare or productivity. Disease comes into your herd through one of four ways – on animals, in vehicles, on people, or other ways, such as feed, wind or water. You need to assess each disease route onto your farm to quantify disease risk and implement a control strategy. For example, when visitors come to your herd how do you ensure they have protective clothing that is clean and disinfected? Simple you provide a range of boots, leggings and jackets for visitors and insist they wear them. Responsible people have no problem with this request.
How do you minimise the risk of diseases in the new herd? All herds will have disease problems of some sort and knowing these when buying a complete herd minimises your risk of exposing cattle to new diseases and allows you to manage the problems. Alternatively you may source your cattle from two or more herds, but in all cases you will need to look at the disease profile of each herd and discuss with the vendor and your vet adviser which herds can be mixed to give the least impact. This of course depends on honesty and trust between the parties and providing the vendor is genuine there should be no problem in divulging this information openly between you.
Control of disease needs as much time and investigation as all the other factors in setting up your herd. Buying whole pig herds has long been a feature of the pig industry where biosecurity is key to success. Where a pig herd is offered for sale prospective purchasers will ask for a disease and performance profile of the herd and ask their vet to inspect and sample the herd for disease risk. Starting with a known disease risk profile allows the new herd to manage any risks and be ready to deal with them.
What are the practicalities in mixing cattle into the new herd?
First and foremost you will need at least two separate cattle sheds or ideally housing on separate farms to avoid nose to nose contact between incoming groups and those already there. One shed serves as the accommodation for the established herd (main shed) and the other for accommodating incoming stock (isolation/quarantine shed). This provides a period where incoming cattle can be allowed to settle and any blood tests, vaccinations and treatments can be carried out. Once treatments are complete and all tests are clear they can move to the main shed. Any cattle not responding to treatment or failing tests should move into another separate quarantine area until a decision is made on dealing with the animal.
Ideally cattle should be brought in either as one complete group or in batches with about five to six week intervals. This allows time for tests to be carried out, results returned and most vaccination
THE JOURNAL APRIL 2015 55
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