Better Pork - February 2004Study shows that vaccines provide good coverage against PRRS field virus strains
But the question remains: Why do we see such variable responses from one herd to the next in the field?by S. ERNEST SANFORD
At the fourth International Symposium on Emerging and Re-emerging Pig Diseases, held in Rome, Italy, in July 2003, Dr. Mike Roof presented a paper summarizing the results from 10 different laboratory studies, all done by independent researchers, in which the efficacy of the two PRRS modified live virus (MLV) vaccines was tested against challenges by several heterologous strains of PRRS viruses.Conventional weaned pigs were used in each study. The pigs were vaccinated at three weeks of age with one of the two PRRS vaccines (see Table 1). Seven different virulent PRRS field virus strains were used to challenge the vaccinated pigs; five of the seven viruses were used on pigs vaccinated with Ingelvac PRRS MLV vaccine; the other two viruses against pigs vaccinated for Ingelvac PRRS ATP. All challenge viruses were heterologous to the vaccine virus in the vaccinated pigs except for Study #2. The parent strain of the vaccine virus was used in Study #2. Pigs were challenged =28 days (=4 weeks) after vaccination, except in Study #2 in which the challenge was 21 days after vaccination. Pigs were euthanized 14 days post-challenge and lungs scored for percent of pneumonia.
The five PRRS field viruses used to challenge the Ingelvac PRRS MLV-vaccinated pigs were between 84 and 99 per cent in their genetic relationship to Ingelvac PRRS MLV vaccine virus on ORF 5 sequencing. The two other field viruses used to challenge the Ingelvac PRRS ATP-vaccinated pigs differed by 85-90 per cent on ORF 5 sequence homology from Ingelvac PRRS ATP vaccine virus. The two vaccine viruses were 11 per cent different from each other on ORF 5 sequence.
What were the results? Pigs in the groups vaccinated with Ingelvac PRRS MLV had lung lesions (pneumonia) that were reduced by 74 to 97 per cent compared with the unvaccinated controls (Table 1) and 54-74 per cent reduction in pneumonia lesions in groups vaccinated with Ingelvac PRRS ATP vaccine compared with unvaccinated controls (Table 1).
The data from these 10 studies show that both commercial PRRS vaccines provided good protection against a wide variety of PRRS field virus strains. The modified-live virus vaccines provided this protection irrespective of:
Protection was provided regardless of whether the isolates were genetically closely related or vastly different from the vaccine viruses, based on ORF 5 sequence homology.
- The origin of the field viruses, whether old or recent isolates.
- Moderate or severely aggressive (e.g.. acute PRRS) isolates.
- Endemic or emerging genotypes of PRRS viruses.
Table 1. Summary of gross lung lesions Per cent lung lesions (pneumonia) # Ingelvac PRRS
vaccine usedUnvaccinated
pigsVaccinated
pigsControls Pneumonia reduction
in vaccinates (%)1 PRRS MLV 31% 0.85% NA 97% 2 PRRS MLV 38% 9.9% 0.12% 74% 3 PRRS MLV 81% 10% NA 88% 4 PRRS ATP 70% 18% 0% 74% 5 PRRS ATP 81% 37% 27% 54% 6 PRRS MLV 47% 8% 2% 83% 7 PRRS ATP 23% 6% 0% 74% 8 PRRS MLV 26% 1% 0% 96% 9 PRRSS MLV 16% 2% 0% 88% 10 PRRS MLV 40% 12% 0% 70% The data show that both commercial PRRS vaccines provided distinct protection against a wide variety of PRRS field virus strains. The modified-live virus vaccines provided this protection irrespective of the origin of the field viruses. Protection was provided regardless of whether the isolates were genetically closely related or vastly different, based on ORF 5 sequence homology, from the vaccine viruses.
I had been aware of some of these studies prior to Dr. Roof's presentation at the Rome symposium. However, it was not until he had them compiled and delivered as a single presentation that the true impact of the studies was clearly driven home. These are very compelling results.
This then raises the question, why do we see such variable responses from one herd to the next in the field? What is so different in the field that makes it not consistently produce the same results as those obtained in these independent studies?
One immediate answer, of course, is that situations in the field can vary widely with multiple different concurrent diseases, environmental and management factors that can and do influence the outcome of any interventions. Also each farm is different (haven't you heard that one before?) and has to be investigated and treated individually by implementing its own farm-specific intervention strategy.
Something else that stands out in these trials is that the pigs were vaccinated at least four weeks before they were challenged by the PRRS virus. We now know that it takes several weeks (at least four weeks and more than that is even better) for the vaccinated pigs to build sufficient immunity to be protected against the respiratory form of PRRS. That time factor of four weeks between vaccination and exposure to the field virus is often lacking in field situations.
There are several "Take Homes" that can be extracted from these studies.
- In the growing pig respiratory model, the PRRS vaccines are able to provide protection against a wide variety of different strains of PRRS virus.
- Protection is provided by the PRRS vaccines against moderate and very aggressive (virulent) strains of PRRS virus.
- Protection is maximized when vaccinated pigs have had at least four weeks after vaccination before they face the field virus.BP
S. Ernest Sanford, DVM, Dip. Path., Diplomate ACVP, is a swine specialist with Boehringer Ingelheim Vetmedica (Canada) Ltd. in Burlington.
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back Swine apprenticeship program gets underway at Ridgetown
With most of the program spent on the farm, students learn a hands-on approach that can equip them for careers in farming or related, specialized sectorsby SUSAN MANN
Students enrolled in the swine herdsperson apprenticeship program have an opportunity to earn while they learn.Most of their course time is spent in on-farm training - only 10 per cent of it in the classroom -- and the students are paid for the time they put in being trained. It takes about two to two-and-a-half years to complete the necessary 4,000 to 5,000 hours for the program.
The Ontario Ministry of Training, Colleges and Universities sets the training standards, says Liz Meidlinger, chair of the apprenticeship Link marketing committee. Currently the course, which is being offered at Ridgetown College, has seven to 10 students. Meidlinger says a viable number of people in the program would be a class of 15 to 20 students.
The marketing committee recently hired a co-ordinator, Bill Weaver, who will spend part of his time on attracting young people into both the swine and dairy apprenticeship programs. He will also work to compile a list of employers interested in hiring apprentices, inform the industry about the programs and talk with his counterparts in other provinces to find out about their programs.
"Apprenticeship's hands-on approach encourages the sort of 'pride in production' that benefits the industry as a whole," Weaver says. He adds that "apprenticeship encourages a well-rounded understanding, perfectly suited to agriculture, and fosters employees with vested interests in the industry."
The students entering the program need to have a high school diploma. But students in Grade 10 can start accumulating their on-farm hours as part of the Ontario Youth Apprenticeship program. Those students can't do the off-farm portion of the apprenticeship program until they have their Grade 12 diploma.
To become a swine apprentice, students can find a pork industry employer to hire them and register them as an apprentice with the ministry or they can contact job placement at Ridgetown College, where staff will help direct them to recommended employers in the industry.
Among the things the students learn are safety on the farm and in working with livestock, herd health and management, breeding, nutrition, vehicles and equipment, and manure management. "They'll cover everything in animal husbandry and everything related to on-farm production," Meidlinger explains.
Employers and students, who can have either farm or non-farm backgrounds, have to register with the ministry to be part of the program. The role of the colleges is to deliver the in-class part and help to market the program.
Once they've successfully completed their course, the students will get the designation of licensed apprentice. They'll be able to pursue careers on farms and in specialized sectors related to the pork industry, including as representatives of feed, pharmaceutical, genetics, agricultural financial and retail companies. BP
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back by JIM DALRYMPLE
BP
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back "Sorti-Stall" offers silent electronic selection for slaughter hogs
by NORMAN DUNN
"Sorti-Stall" is the name for a new low-stress concept of automatic weighing and selection for hogs without them ever having to leave their pen.This electronic system, developed by the Danish-Dutch equipment manufacturer Skiold and just now being tested on 100 German hog units, means humans can stay well away from the whole procedure.
The Sorti-Stall system has been specially designed to fit into the increasingly popular "big pen" feeding units where batches of from 250 to 300 hogs are kept together right up to slaughter.
The pen is split between a raised, straw-bedded or part-slatted lying area, usually about 45 centimetres higher, and a railed-off, part-slatted area usually split into two further pens, each with space feeders. Between the lying and feeding sections is a fully-slatted drinking/dunging passage with automatic scraper-cleaning regularly removing dung from beneath the slats to keep smell and air ammonia content down.
To move from the lying to the feeding areas, hogs must pass through a single gate leading to a weighing floor. If two diets are being fed, pre-set weights can trigger a right or left opening of subsequent gates after weighing to direct pigs to the appropriate feeding area. At the same time, the weighing system provides full documentation of hog performance.
Alternatively, a pre-set slaughterweight can lead to slaughter-ready hogs being admitted after weighing into one side of the feeding area, whence they leave via one-way gates onto a railed-off part of the dung passage. There, the hogs can be held without feed for the appropriate time, before being collected for slaughter from a door leading straight off the passage/holding area.
According to Cor Suselbeek, Skiold manager in the Netherlands, the Sorti-Stall idea has led to improved weight gain performances because of the non-stress automatic handling and selection which also offers savings through reducing labour requirements. BP
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back Quebec's moratorium on hog farm expansion stays in place for now
Those who thought that the new Liberal government would phase out the restraints on expansion, as previously planned, have been disappointed. Quebec society, it seems, is not ready to face another explosion in hog numbersby FRANCE GROULX
No relief is in sight for Quebec's pork producers from the moratorium on expansion of hog facilities imposed in the spring of 2002. The new Liberal government, through the Ministry of the Environment, intends to extend the moratorium until the end of 2004, so disappointing those who had hoped that the election of Jean Charest would put the industry back on the development track.The agreement for resuming the building of new hog facilities anticipated a gradual restart to construction or expansion projects in December 2003. But the new government has shown no indication that it intends to keep the promises made by the old PQ administration.
The moratorium put a stop to all expansion of hog facilities in more than 200 municipalities where, statistically speaking, there is insufficient land to receive the amount of manure produced in that area. Elsewhere, restrictive measures that are attached to construction permits are so severe that, in effect, the hog operations are subject to a quasi-moratorium.
The decision to extend the moratorium stems from a huge 700-page report that has cost the province's taxpayers around $1.5 million. The amount invested in the Commission on the Sustainable Development of the Pork Industry is in proportion to the level of social unrest resulting from the rapid expansion of the hog population in Quebec. In the last decade, hog numbers have doubled to the point that Quebec now slaughters slightly more than seven million hogs annually.
Environmental requirements for the protection of soil and water oblige producers to have land in sufficient acreages to spread all their manure, one of the reasons the price of land has gone up by an average of 12 per cent a year since 1995. Add to this the accelerated disappearance of woodlots on farms and an increase in odours coming from liquid manure, and you have a recipe for neighbourhood conflicts.
Between the fall of 2002 and the spring of 2003, the inquiry held more than 130 public hearings across the province. The four commissioners also visited production and processing facilities in other Canadian provinces, the United States and in three European nations.
The report, which was made public at the end of October, cuts a wide swath. Its recommendations include an increase in powers for municipalities, limits on subsidies for integrators, public consultations for the establishment of new hog operations, taxes on mineral fertilizers, regulation of woodlot cutting, an emphasis on the use of bedding in livestock operations rather than liquid manure, removal of producer immunity from civil indemnities . . . the list goes on.
The acceleration in the industry's expansion has been the result, in large part, of integrated farms. Generally, the producer puts up the barn and the manure storage structures and, in exchange, the integrator provides a guaranteed supply of hogs, feed and technical services.
The producer under contract receives an income proportional to the level of efficiency and the market price of hogs. As for the integrator, they have access to government subsidies per head of pork without any limits on volume produced. The report proposes that subsidies to integrators be limited in favour of family farms, defined as farms which employ four persons or less.
If a ceiling is placed on subsidies to integrators, there are fears that they will react by skirting around the mandatory electronic auction operated by the Fédération des producteurs de porcs du Quebec. On the one hand, prices risk dropping substantially if this happens, and on the other, the marketing links with supermarket chains will be weakened.
The report recommends that municipalities should have more powers in the area of land management, but the Union des producteurs agricoles, the official representative of Quebec's farmers, is flatly opposed to this, and is determined that agriculture should stay under provincial jurisdiction.
Since June 15, 2003, all hog farms have been obliged to have a phosphorus register and fertilization plan. The management process aims to take into account all sources of phosphorus brought onto the farm from manure and mineral fertilizers, and all those from spreading manure from livestock on the farm. To date, 50 to 75 per cent of hog producers have conformed to these demanding requirements.
Pork producers have so far been very diplomatic in their response to the report, but the government is wary about allowing construction projects to restart, conscious that Quebec society is not ready to face another explosion in hog numbers. But, in agriculture as in other economic sectors, to stagnate is to go backwards. BP
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back International standards on animal feeding are on the horizon
By the fall of 2004, an international task force expects to have complete a Code of Practice on Good Animal Feeding that will establish a feed safety system covering the whole food chainby JANICE MURPHY
Today's consumers expect the highest quality food products and the Canadian food industry has responded by initiating quality assurance programs at each link in the food chain. Ultimately the goal is to have such programs at every step of production, literally from the farm right through to the dinner table.While we have been busily working away at developing and implementing the Canadian Quality Assurance (CQATM) Program in the pork industry, more work is going on behind the scenes at the international level to address feed-related food safety concerns on a global scale.
Since June 2000, the Codex Ad Hoc Intergovernmental Task Force on Animal Feeding has been focusing on developing animal feed production and feeding standards. Recent history has reminded us that the basis for healthy and safe foods is established during the production of animal feed and is closely linked to the feeding of animals in our modern production systems.
The Task Force's draft document, Code of Practice on Good Animal Feeding, addresses all avenues of feed production. Its goal is to establish a feed safety system for food-producing animals which covers the whole food chain, taking into account relevant aspects of animal health and the environment in order to minimize risks to the health of consumers. As you might expect, it focuses specifically on feed manufacturing and on-farm feeding practices.
The Code itemizes the minimum standards for good animal feeding practices on-farm and good manufacturing practices during the harvesting, handling, storage, processing and distribution of feed and feed ingredients. The Code suggests that efforts should be made to identify, control and minimize any undesirable substances in feed ingredients, such as pesticides, pathogens or mycotoxins. It specifically mentions that animal products that could be a source of the BSE agent should not be used for feeding directly to, or in preparing feed for, ruminants. Additives must be subjected to risk assessment for safety and be approved for use in animal feed. In addition, antibiotics should not be used to promote growth in the absence of a public health safety assessment.
The Code contains quality assurance requirements for all participants in the feed chain, focusing on such things as buildings and equipment, personnel training, storing and transport of feed, as well as sanitation and pest control at all stages in the process. There are also requirements for record keeping, which is vital in tracing back feed when actual or potential health risks are identified that could lead to the withdrawal or complete recall of products.
For farms where crops are grown and fed, the Code applies to the cultivation, manufacture, management and use of crops and complete feeds, with emphasis on the three types of potential contamination: biological, chemical and physical. Pesticides and fertilizers must be used correctly, and it is important that farm animals be only given feed appropriate for the particular species and class of animal for which it is intended. The Code also emphasizes the basic principles of animal feeding so as to ensure proper mixing procedures, adequate hygiene, routine sampling and analysis of feeds and feed ingredients.
Not surprisingly, one of the major discussion points during the drafting of the Code surrounded the use of genetically modified organisms (GMOs) in feeds. In the current draft of the document, the Task Force suggested that GMO ingredients in animal feed could be subjected to a risk assessment in relation to food safety and, as such, require special labelling.
In May of 2003, the Task Force on Animal Feeding completed what was intended to be the final draft of the proposed code. However, a number of controversial areas could not be resolved, so the Codex commission has extended the task force mandate by one year. The three main sticking points involve the definition of feed additives, labelling of feeds that contain GMOs and the record keeping required to maintain traceability of feed and feed ingredients.
The task force is scheduled to meet in May 2004 in an effort to resolve the outstanding issues. If all the remaining concerns can be addressed, the Code of Practice on Good Animal Feeding could be in place by the fall of 2004. For a copy of the latest draft of the Proposed Draft Code of Practice on Good Animal Feeding, visit: ftp://ftp.fao.org/codex/alinorm03/Al0338ae.pdf.
What is the Codex Alimentarius?
The Codex Alimentarius represents the code of food standards throughout the world. It is a detailed 13-volume collection of Standards, Codes of Practice, Guidelines and Recommendations for dealing with food of all shapes and sizes. As the world's authoritative reference on food standards, it is used by national food inspection systems, health authorities, the World Trade Organization, the food industry, scientists and consumer advocates.The Codex Alimentarius Commission (commonly referred to as "Codex") was formed in 1962 by the World Health Organization and the U.N. Food and Agriculture Organization. Codex is an intergovernmental organization whose mandate it is to safeguard the health of consumers, enhance fair international trade practices, co-ordinate work on international food standards, and manage the compiling and updating of food standards.
Currently, Codex consists of 165 member countries, including Canada. To accomplish its mandate, Codex has established 28 different committees and a number of (presently three) ad hoc intergovernmental task forces. While the standing committees are considered permanent, the task forces are organized to address specific Codex issues as they arise.
The Standards are developed through the work of the various committees, working through an eight-step or accelerated five-step process from proposal to adoption. The process provides for input from all interested parties involved in the food chain. The Commission makes every effort to reach agreement on the adoption or amendment of standards by consensus. Voting is rare, and only occurs when efforts to reach consensus have failed.
There is no obligation for countries to adopt Codex standards as a member of either Codex or the WTO. However, if there was a trade dispute, the WTO could sanction penalties against a country that could not justify a more stringent, trade-restrictive requirement than that specified in the Codex standard.
The food standards, guidelines and other recommendations of Codex are based on scientific principles of analysis and evidence, involving a thorough review of all relevant information, so that the standards developed assure the safety of the food supply. BP
Janice Murphy is Swine Nutritionist with the Ontario Ministry of Agriculture and Food in Fergus. E-mail janice.murphy@omaf.gov.on.ca
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