Better Pork - August 2005PCV2 disease is on the rise in Quebec and Ontario herds
With conventional treatments proving largely ineffective, good management practices have been the main measures used to control PCV2. However, PCV2 vaccines are under development or already in use in Europeby S. ERNEST SANFORD
Porcine circovirus type 2 (PCV2) and its associated diseases have been a known entity in our swine herds for more than a decade. For the most part, it has been of minor importance, occurring sporadically in a small number of herds. Even in the affected herds, with the rare exception, it has been troubling but usually not devastating.All that changed last winter when outbreaks of PCV2 disease erupted in numerous herds across Quebec. Less dramatic but equally troubling is that, in Ontario, we have seen a steadily escalating pattern of increased PCV2-related disease outbreaks last fall and winter.
What is PCV2 and what does it do? There are two types of circoviruses in pigs -- PCV1, which is harmless (non-pathogenic), and PCV2, which causes PMWS (porcine multisystemic wasting syndrome), contributes to the PRDC (porcine respiratory disease complex) and has been linked to at least two other entities, PDNS (porcine dermatitis and nephropathy syndrome) and reproductive failure.
PCV2 is the major etiological agent in PMWS. The presence of PCV2 is necessary but often insufficient for clinical PMWS to develop unless co-infection with one or more other agents (usually PRRS virus or parvovirus, or some other co-factor (mineral oil-in-water adjuvant as an immune stimulant) is present. PMWS affects pigs six to 16 weeks of age, but especially pigs between eight and 12 weeks old. Clinically, PMWS is characterized by growth retardation, unthriftiness and wasting, skin pallor, dyspnea, diarrhea and enlarged peripheral (especially inguinal) lymph nodes.
Gross postmortem findings include non-collapsed lungs (interstitial pneumonia) and generalized lymph node enlargement. Mortality rates of 10-40 per cent are common in severely affected herds.
In combination with one or more other agents -- PRRS, swine influenza virus and Mycoplasma hyopneumoniae - PCV2 is now recognized as a contributor to the porcine respiratory disease complex (PRDC).
As for Porcine Dermatitis and Nephropathy Syndrome (PDNS), this manifests itself as red, raised, varying-sized, irregularly shaped to expanding and coalescing lesions on the skin of the chest, belly, thighs, rump, front and back legs of grower to finisher age pigs. The skin lesions may eventually crust over and form scabs. Spontaneous recovery may occur, but recovered animals remain permanently unthrifty. Morbidity is usually very low but mortality is high ( equal to or greater than 15%).
At postmortem, lymph nodes are enlarged and red. Kidneys are mottled and have multiple small red hemorrhages scattered over the surface. The cause is unknown but is believed to be a hyper-immune reaction in the walls of the blood vessels, which results in the severe skin and kidney lesions seen away from areas that the blood vessels supply. PCV2 is usually found associated with these lesions.
The connection of PCV2 to reproductive failure is still not conclusively proven. The most compelling cases have been in start-up herds in which late gestation gilts have experienced abortion storms, premature births and birth of pigs with high preweaning mortality resulting from heart failure secondary to severe myocarditis, in which there is massive PCV2 infection in and around the heart lesions.
PCV2 is a very small, circular (hence the name "circo") DNA virus. It is resistant to disinfectants and drying and it survives very well in the environment. A prolonged viremia persists after infection and the virus is shed in bodily fluids and in semen. Although PCV2 has been shown to be necessary for PMWS to occur, there usually has to be something else present that triggers PCV2 disease.
The reasons for this line of thinking are that PCV2 virus appears to be ubiquitous. Nearly all herds tested, and all pigs in those herds, are infected with the virus. So it seems that PCV2 is subclinically present in most or almost all of our herds, yet only a small percentage of herds experience any PCV2-related disease. Furthermore, in most affected herds, only a small number of pigs in the herd usually come down with PCV2 disease, although all pigs in the herd are infected with the virus. The triggers that have been identified to promote an outbreak of PCV2 disease include:
- PRRS virus infection;
- Parvovirus infection;
- Mycoplasma hyopneumoniae infection;
- Vaccines containing mineral oil-in-water adjuvants.
An initial diagnosis can be made from clinical signs of wasting and enlarged peripheral lymph nodes in late nursery and grow-finish pigs. Definitive diagnosis depends on identification of characteristic granulomatous histological lesions in several organs, including lung, liver, kidney and especially lymph nodes. Large numbers of PCV2 antigen, identified with special staining techniques, are associated with the lesions.
Conventional treatments have been largely ineffective. In affected herds, however, it becomes even more important to control known co-infecting diseases, such as PRRS and mycoplasma. If using a vaccine with mineral oil-in-water adjuvant, changing the timing of vaccination so it does not coincide with the time of infection with PCV2 removes the stimulus that activates PCV2 disease.
Good management practices have been the main measures used so far to control PCV2 disease in affected herds. These include:
Serum inoculation has been used in Europe with some reports indicating good success, others giving less than satisfactory results. Serum inoculation consists of harvesting serum from pigs (90 kilograms and above) that have recovered from PMWS and injecting 10 to 20 millilitres subcutaneously into nursery pigs in the same herd as soon as they show early signs of developing the disease. Antibodies in the serum are expected to be protective against development of PCV2 diseases. Treatment is repeated 10 days later if necessary.
- All-in/all-out (AIAO) pig flow;
- Unidirectional pig flow;
- Maintenance of good air quality;
- Strict hygiene;
- Good intake of colostrums;
- No overcrowding;
- No co-mingling of pigs from different sources;
- Separation of sick pigs from the rest of the population.
Researchers at Iowa State University have successfully reared several batches (50-80 pigs per batch) of PCV2-free pigs by early weaning them at 10-14 days of age and rearing them off-site. It is not known how long these pigs remain PCV2 free.
A PCV2 vaccine has recently been launched in Europe, but is not yet available in North America. Other PCV2 vaccines are currently in development, likely to become available in the very near future.BP
S. Ernest Sanford, DVM, Dip. Path., Diplomate ACVP, is a swine specialist with Boehringer Ingelheim Vetmedica (Canada) in Burlington. esanford@bur.boehringer-ingelheim.com
© copyright 2005AgMedia Inc..
back An energy audit - the first step in improving energy efficiency and reducing costs
An audit need not be a complicated process. But it can lead to substantial ongoing cost savings and an improved operating environmentby RON MACDONALD
The cost of energy, regardless of its source, will unfortunately continue to rise for the foreseeable future. Before any farm business owner, manager or operator can make informed decisions about improving energy efficiency, it is necessary to understand how energy is used. An energy audit is an important first step.An energy audit is defined as a "series of actions aimed at the identification and evaluation of energy management opportunities (EMOs) within a defined site." The goals are as follows:
- To clearly identify the different types of energy use.
- To understand how this energy is being used.
- To identify alternatives that could reduce energy costs.
- To develop a cost-effective implementation strategy, based upon an economic analysis of the alternatives.
Many EMOs are related to good maintenance practices that have the added benefits of decreasing other operating costs. Improving energy efficiency can provide the farmer with the opportunity for substantial ongoing cost savings, a better understanding of the operating cost of production, a possible reduction in nuisance breakdowns and emergency repairs, and an improved operating environment.
An energy audit need not be a complicated process. In general, the audit process can be divided into six steps: preparing for the audit; performing the farm survey and inspection; analyzing the data; implementing the audit recommendations; documenting the audit activities; and following up to review the results.
Energy consumption on the farm is predominantly concerned with lighting, heating and motors. EMOs result from a careful review of both use patterns and technology choices, and can involve the following:
- Switching to energy-efficient lighting systems;
- Use of dual or natural ventilation where possible;
- Insulation of bare tanks and lines, as well as the building itself;
- Installation of storm windows, doors and weather stripping;
- Use of "set-back" or turn off equipment during downtime;
- Switching to energy-efficient motors;
- Rescheduling farm operations to reduce peak demand;
- Installing milk heat reclaim systems.
Whether or not you conduct the assessment yourself or get a more detailed audit from an energy expert is an individual choice. An initial self-assessment, using the Environmental Farm Plan, is a good place to start, but a more comprehensive expert audit performed can provide significant benefits. An energy audit, particularly a walk-through one, is an exercise in data collection and analysis. When performed by the owner, costs are minimal. A more detailed audit replete with cost/benefit recommendations may cost $200-$2,000 when performed by a local energy specialist or professional engineer. BP
Ron MacDonald, P.Eng., is an agricultural engineer with Agviro Inc. in Guelph.
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back Eight Ontario hog farmers join shelter belt demonstration project
by MIKE MULHERN
Hog farmers who want their barns to look better, smell better and have better snow and temperature control should think about planting windbreaks. That's the message Ontario Pork and the Canadian Pork Council are trying to get out in a joint project designed to train foresters in the art of planning and establishing windbreaks.As part of the program, eight Ontario hog farmers will have a professionally planned windbreak planted around their hog barns and lagoons as demonstration sites. The first one will be planted this fall and the other seven next spring.
Sam Bradshaw, environmental communications specialist with Ontario Pork, said the first part of the program is to train foresters, conservation authority staff and stewardship coordinators in the art of planning, planting and maintain windbreaks around farm buildings. The workshops are being set up with funding from the technical assistance program of Greencover Canada.
Anne Loeffler, a soil and water conservation technician from the Grand River Conservation Authority, will coordinate the Ontario program. André Vezina, a Quebec forester with 21 years experience with windbreaks and shelter belts, will be leading the Ontario workshops. The first is June 27 and 28 at the Maitland Valley Conservation Authority office in Wroxeter.
Planning a windbreak, says Vezina, is more complicated than people think. Snow accumulation, and drainage tiles need to be considered. Heating may need to be reduced and the project has to look nice.
Establishing an effective windbreak, Vezina said, could take five to 10 to 15 years. He said in Quebec, where about 100 windbreaks have been installed around hog barns following a demonstration program that started in 2000, they include hybrid poplars for fast windbreak establishment along with other species.
Once a plan is approved, he said, they have to prepare the soil the way you would garden soil by tilling it thoroughly. "We don't especially fertilize because we think water is the most important thing." He said they use plastic mulch to plant trees and shrubs, beginning with trees at about 60 cm and shrubs at 30 cm. "Sometimes," he said, "we like to go with bigger trees, but it takes more time planting."
The composition of the windbreak, he said, also depends on the diligence of the farmer. "We know some people are not going to maintain their windbreak, so we don't plant a shelter belt which asks for too much care. Some farmers don't mind maintaining it, so we put in some shrubs and trees which ask for more care."
Shrubs are planted to get cover from the ground up to the top of the tallest trees. Species vary, depending on soil type, but often include hardwoods which can later be harvested for logs.
Vezina said the initial workshops will be about planning shelter belts around farm buildings, with following workshops on soil preparation and planting and then workshops on shelter belt maintenance.
Loeffler said most conservation authorities in Ontario offer tree planting programs now, along with technical assistance on how to get trees established. "What we're trying to do (with the workshop program) is to take it to a higher level and get a better understanding of how to properly design windbreaks around barns. If you don't do it right, you could potentially dump a lot of snow in the wrong location or you could block the ventilation."
She said the technical assistance program offered by the Grand River Conservation Authority is free. They will also engage contractors to plant trees and they try to connect farmers with funding programs.
The eight hog farms where demonstration windbreaks will be established are going to be selected based on submitted windbreak designs, though the final selection process hasn't been settled. "We are looking for geographic distribution across the province," says Loeffler. "There will be more demonstration sites in counties that have the highest concentration of pig farms." Visibility of the farm and the degree of problems they have will be also factored in.
Loeffler says a guide on shelter belt planning and maintenance will be available later in the year. It is based on a similar brochure developed by André Vezina for hog producers in Quebec. Cedric MacLeod, greenhouse gas mitigation coordinator with the Canadian Pork Council, says one of the benefits they expect to get from shelter belts around hog barns and lagoons is odour control. "When you get odours moving across the landscape, it's because the wind has access to the surface of your manure storage, so it actually creates that bit of wave action on the top of the storage and that wave action releases odor and it travels with the wind across the landscape."
MacLeod also said aesthetic benefits can be achieved. "With a couple of rows of trees around a barn, you can still tell it's a barn, but it just makes the site a little nicer."
Robinson's interest in trees led to summer jobs at the Maitland Conservation Authority during his time at the University of Guelph where he studied resource management. Now, Brent works with his mother and father, Rose and Bob, his two brothers Scott and Jeff, and their wives, running a 3,200-sow farrow to finish operation where they also sell breeding stock and market hogs. "We have a variety of windbreaks on five different farms, generally on the field edges, so that allows for ease of farming operation," Brent says.
The windbreaks are pleasing to look at, he said, and it can generate profit as well as all the benefits associated with wind breaks. "It has the long-term ability to maintain itself because you can actually take out a tree or two as a log, and maybe make some money while the windbreak remains, regenerating itself."
Brent says that adding windbreaks has been a staged process, starting with the north and west wind sides. "It's a big undertaking to plan a windbreak correctly and you have to put in a lot of effort to get them established." Now he starts with larger stock, now, to get windbreaks established. "When you start with the little ones, it takes them two or three years just to get established. The survival rate is better with larger stock."
Brent says that grant programs in the past helped share some costs, but not always. "We look at it as part of our farming expense. If there isn't a grant program, we just do it ourselves."
John Sharpe, a policy analyst with Agriculture Canada, manages Greencover Canada, a five-year, $110-million program that ends March 31, 2008. He says that, while each province is different, most provide up to 50 per cent of the cost of shelter belts for barns.
Nancy Cherny, environmental programs officer for Ag Canada, confirmed that Ontario farmers can qualify for 50 per cent support up to a cap of $10,000 but they must have an approved environmental farm plan before applying for cost-share dollars.
Greencover Canada in Ontario is managed through the Ontario Soil and Crop Improvement Association. The association also administers the environmental farm plan and the peer-reviewed action plan portion of the environmental farm plan, which is essential to access the cost-share programs for such things as shelter belt establishment. BP
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