Beef HealthCheck NEWSLETTER SUMMER EDITION 2015
Guest Contributor P2 The importance of capturing and recording health data.
Dr Stephen Conroy, ICBF, G€N€ IR€LAND
Liver Fluke – The Facts P4
Animal Health Ireland, Main Street, Carrick-on-Shannon, Co Leitrim. Tel: +353 (0) 71 9671928, Email: firstname.lastname@example.org www.animalhealthireland.ie
The importance of capturing and recording health data
Dr Stephen Conroy, ICBF, G€N€ IR€LAND Progeny Test Centre, Tully, Kildare
R ecent work by the Irish Cattle Breeding Federation (ICBF) and Teagasc has demonstrated that there is a genetic component among animals in the response (i.e., negative or positive) to tests for different diseases such as Johne’s Disease and TB. This discovery has led to the idea that other diseases such as pneumonia, scour, and mastitis, may also have a genetic component which could be subsequently exploited in a national breeding programme. Given that breeding has contributed to approximately 50% of gains in performance in cattle (and other species) it is important to quantify the potential of cattle breeding as part of a strategy to achieving a healthier national herd. Genetics is cumulative and permanent which means that when good genes are introduced into a population of animals they have long-term favourable effects. Equally, bad genes can have long-term unfavourable effect and can be difficult to breed out. It is well recognised that animal health is one of the major costs associated with raising cattle in Ireland. Teagasc has estimated that the average veterinary/animal health costs are approximately €60 per dairy cow in 2014 1 . Losses from liver fluke infection are even more shocking with an estimated €90 million in losses annually and up to 20% reduction in meat yield when cattle become infected 2 . Herd health status can be maintained through the appropriate management (e.g., biosecurity), but ICBF is attempting to complement such strategies by addressing the genetic component of animal susceptibility to these different health events. In March of 2014, ICBF launched a new health recording screen (see below). The screen allows farmers to record health and disease events. To date, fourteen hundred farmers have recorded health events through to the ICBF database. Also, some abattoirs are now recording data on fluke, pneumonia and other diseases on all animals at slaughter.
1 https://www.agriland.ie/farming-news/tips-average-veterinaryanimal-health-costing-dairy-farmers-e60cow/ 2 http://www.animalhealthireland.ie/ckfinder/userfiles/files/20130517%20PC%20LiverFluke%20Ver%202_0.pdf
What are the benefits of sending health information to ICBF? By capturing large volumes of data on farm in real-time, ICBF can develop a world-class health index. This health index will aid in identifying sires that can breed animals less susceptible to disease whilst still performing well. The index will also identify calves and cows that are more robust and are less likely to succumb to disease. Accurate genetic evaluations are predicated on access to large quantities of data to identify sire family divergence in susceptibility to disease. Therefore, it is important that all farmers participate in recording health information. Unless a high volume of data is available a breeding programme to improve the health status of the national herd will not be possible. If you would like further information or have any queries relating to the recording of health events through ICBF, please email email@example.com.
Why record? To have healthier cows and calves!
Liver Fluke – The Facts Rebecca Carroll Assistant Programme Manager, Animal Health Ireland
L iver fluke is a parasitic disease of grazing animals, including cattle, caused by a flat worm (Fasciola hepatica) . Economic losses in beef cattle caused by liver fluke are mainly due to lower carcase weights and the increased time required to finish affected cattle. In addition, fertility may also be reduced and the livers of affected animals will be condemned at slaughter. Liver fluke depends on an external host, the mud snail, as well as cattle, to complete its lifecycle. The role of the snail, which prefers muddy conditions and poorly drained areas, means that the incidence of liver fluke is far greater in the wetter areas of the country and in years when there is high summer rainfall. In Ireland, liver fluke infection can be a problem all year round. However, most cattle are infected during the summer and autumn, from snails that have built up over the summer. Cattle do not develop a protective immunity to liver fluke and cattle of all ages can be infected and re-infected with liver fluke.
What are the signs that liver fluke infection may be present in your herd? Most cattle infected with liver fluke do not show obvious signs, however subclinical infections can have adverse effects on growth rates and thrive in cattle. Severe infections can occur with animals showing a variety of obvious signs such as: • oedema under the jaw (bottle jaw) • anaemia • poor coat condition • lack of appetite Remember the severe cases are often just the ‘tip of the iceberg’ and many other animals in the herd may be sub-clinically affected. Monitoring, control and treatment Fluke burdens can be monitored on beef farms by using a combination of faecal egg counts (FEC) and data relating to liver condemnations from meat factories. It takes approximately 10-12 weeks before fluke eggs appear in the faeces following infection, so egg counts for fluke should generally be done at least 3 months after turnout. However, adult fluke (and therefore eggs in the faeces) may be found immediately after turnout if animals were not correctly treated at housing. Where fluke infection is present, identification and exclusion of snail habitats from livestock offers some measure of control. • improve drainage • fence off wet areas with poor drainage • take reasonable measures to prevent poaching • avoid grazing “flukey areas” in the autumn and the winter, when the incidence of disease is at its highest On many farms in Ireland it is not possible to completely eliminate the mud snail and liver fluke, and most control programmes rely on flukicidal treatments. The choice of product and frequency of use will depend on the level of fluke challenge, the time of year, and the management and husbandry systems on the farm. All flukicidal drugs on the market are effective in treating adult fluke but only certain products are effective at treating early immature and immature fluke. Where products that only kill later stages of fluke are used, immature fluke may remain in the liver and continue to develop.
A strategic dose, in early- mid summer, designed to reduce the build-up of contamination on pasture may be useful on farms with a high risk of fluke. At this stage in the year, fluke in cattle that have become infected after turnout by eating fluke larvae (metacercariae; Figure 1) will not yet have developed to maturity, so a product with activity against immature fluke should be used. Adult fluke may also be present in these cattle, if they were not successfully treated for fluke at housing.
Farmers and their vets should assess the risk of liver fluke in the late summer/ autumn, taking into account summer rainfall, historical risk of fluke on the farm, liver results from meat factories and FEC results. Depending on the risk, treating cattle at grass for fluke should be considered. The fluke found in cattle in autumn are likely to be a mix of adult and immature fluke, which have developed from infections early in the summer and more recently respectively. Cattle that are returned to pasture after treatment are likely to be re-infected with fluke. A fluke dose at housing (and repeated 2 months after housing, if required) should be given to most cattle in Ireland, apart from those on the driest farms.
Further information on liver fluke can be found in Animal Health Ireland’s leaflet ‘Liver fluke the facts’. http://online.pageflippdf.com/fitx/jxbp/
IBR and potential beef AI sires
David Graham, Programme Manager for Biosecure Diseases, Animal Health Ireland
‘IBR’ stands for ‘Infectious Bovine Rhinotracheitis’. IBR is caused by Bovine Herpes Virus-1 and is spread mainly by close contact between animals, although airborne spread over distances up to 5m can occur. IBR can also be spread through semen from infected bulls. Contaminated equipment and people who have recently handled infected animals may also spread IBR. IBR infection is very common 70- 80% of all Irish herds contain at least one animal infected with IBR, with no marked difference in prevalence levels between beef and dairy farms. The proportion of infected individual animals on a farm can vary widely. Some herds may have only a single infected animal. More commonly, many animals are infected, and in some cases all animals can be infected. Primary IBR infections The first time cattle are exposed to and infected with IBR, the virus damages the surface of the nose and the upper airways and may enter the blood to spread to other parts of the body. Some primary infections produce
no apparent clinical signs while others can be very severe. Latent infection and reactivation
After recovery from primary infection the virus survives within the nerves of the infected animal. The animal is now a carrier but is not shedding the virus. This is called a latent infection. During periods of stress, the virus can reactivate within a latently infected animal. This typically does not cause clinical signs to develop in the carrier animal, but the virus can then be excreted again, spreading to other animals and causing an outbreak of disease (Figure 1).
Figure 1. Spread of IBR following reactivation and shedding of virus from latently infected animals
Latently infected carrier animals are almost always detectable by antibody testing and will continue to test positive for their entire life. There is no treatment that can remove latent infection from an animal. However, regular vaccination of latently infected animals can help to reduce reactivation and transmission to other cattle. A very small proportion of carrier animals may test negative for antibodies. These are called sero-negative latent carriers (SNLC). These are usually created when an animal becomes infected early in life while it still has maternally derived IBR antibodies (MDA) from colostrum. As these animals can pose a serious threat to AI stations it is important to protect young potential AI sires from IBR infection. IBR and AI Stations Semen collection centres in Ireland operate to European standards (Council Directive 88/407/ EEC) to ensure that semen produced meets requirements for trade within the European Union. These standards require that bulls entering semen collection centres are free from a range of disease-causing agents that may be spread through semen, including IBR.
The screening process for entry to semen collection centres begins with testing of bulls before they enter the quarantine facility of the collection centre. IBR is the disease which most frequently results in bulls being rejected for entry to semen collection centres. Only animals that are entirely free from IBR antibodies are allowed to enter semen collection centres. IBR antibodies may be present for the following reasons:
• Infection: the animal has been exposed to the IBR virus. • Vaccination: the animal has produced antibodies in response to an IBR vaccine.
• Colostrum: the animal received IBR antibodies through colostrum. These may persist up to 9 months of age. To avoid this, it is best practice to ensure that in the first 72 hours of life the calf only receives colostrum from a known IBR antibody-negative cow.
Animals that test positive either as a result of infection or vaccination are therefore excluded. Even where the antibodies can be shown by a later negative test to have been colostral in origin, potential sires may still not be selected due to the possibility of their being seronegative latent carriers. Potential AI sires In Ireland, beef bulls have traditionally been purchased by AI companies when they are between 8 and 20 months of age. However, with the increased use of genomics in beef herds, potential beef AI sires will increasingly be identified prior to birth, giving the greatest possible opportunity to manage the calf and its dam appropriately. IBR control in the herd and management of potential beef AI sires It is recommended that all herds address IBR control at herd level. This may require a vaccination programme. Further information on the management of IBR at herd level may be found in the Animal Health Ireland (AHI) leaflet- An information leaflet for Irish farmers, advisors and vets. http://online.pageflippdf.com/fitx/qlbc/ If you are vaccinating, do not vaccinate potential AI sires for IBR . Vaccinated animals will have IBR antibodies and will be excluded from AI stations.
Further steps to protect potential beef AI sires from IBR include: • Identify pregnancies that could produce a potential AI sire • Carry out a herd screening test to establish IBR status of the herd and dam(s) • Identify a source of IBR negative colostrum or a foster dam (if required) • Identify an isolation area for calving and calf rearing (if necessary)
For further details see: ‘A technical guide for veterinary practitioners and breeders of beef bull calves with potential for use as AI Sires’. http://online.pageflippdf.com/fitx/utkk/
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