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Prairie Swine Centre is an affiliate of the University of Saskatchewan
Prairie Swine Centre is grateful for the assistance of the George Morris Centre in developing the economics portion of Pork Insight.
Financial support for the Enterprise Model Project and Pork Insight has been provided by:
Evaluation of potential sources of PRRS virus infection in negative herds
Posted in: Air Filtration, Pork Insight Articles by admin on August 29, 2004 | No Comments
Traditionally PRRS outbreaks were thought to be from replacement animals and tainted semen. New research has shown that the spreading of PRRS and other viruses can also be transmitted by area spread, in transport, by insects and by fomites. This study tries to evaluate some of the other sources of PRRS outbreaks where semen and replacement animals were negative. Over four years 35 PRRS outbreaks were looked at. Of the sites that had outbreaks one was in a sow herd, six in finishing sites and eight in boar studs. When an outbreak was detected blood samples were taken and tested by serology and PCR. The researchers then tried to find the source of the virus. Area spread was considered as a potential cause in pig dense areas and where pigs were transported near other sites. External transport was also evaluated, with special attention to removal of cull sows and slaughter pigs. Other potential sources of infection included mechanical vectors, insects, people, and suspected biosecurity breaches. Reviewing the data found that 83% of the PRRS outbreaks were a result of lateral transfer and 17% were from semen or replacement pigs. For the lateral transmissions, over half were from area spread. Transport due to the removal of cull sows, boars or slaughter and feeder pigs, was strongly suspected in 17% of the lateral infections. Insects were only suspected in one case while biosecurity breaches were suspected in two cases. Seven cases could not be determined and infections had a tendency to happen in colder months. Location of the barns was considered the most likely causes of lateral infection. This study provides insight into sources of PRRS infections other than by replacement animals and semen.
La science au service de l’insémination porcine
Posted in: Air Filtration, Pork Insight Articles by admin on August 28, 2004 | No Comments
Partout à travers le monde, l’insémination porcine a connu un très fort développement au cours des quinze (15) dernières années. Ce développement est dû, entre autres, à la recherche qui a permis des améliorations notables au niveau de cette technique de reproduction. Afin de mieux faire connaître leurs travaux et permettre des échanges utiles, les principaux acteurs ont mis sur pied, il y a plusieurs années, un événement à caractère international : « International Conference on Boar Semen Preservation (ICBSP) », soit Conférence internationale sur la conservation de la semence porcine.
EVALUATION OF PRRSV OUTBREAKS IN NEGATIVE HERDS
Posted in: Air Filtration, Pork Insight Articles by admin on August 23, 2004 | No Comments
PPRS is a detrimental disease to swine producers. To combat PRRS, systems are stocked with PRRS negative animals and semen. Despite this being a measure to prevent PRRS the introducti0n of these animals has been considered the most important source for virus introduction. Although new research has shown that fomites, insects and transport all can help transmit the PRRS virus. The objective of this study is to provide information on the epidemiology of PRRSV breaks in negative systems where the source of replacement animals and semen is negative and to illustrate the ease with which lateral infections occur. Thirty-five PRRS outbreaks were tested during a four year period. They broke down as such: 21 in sow herds, 6 in finishing sites, and 8 in boar studs. Herds were routinely monitored through the observation of clinical signs, blood sample collection and semen testing in the case of boar studs. The samples were compared to samples taken from neighboring sites, and in a lab tests were done to see if the strains were from the same source. Attempts were made to determine the origin of the disease that were considered lateral, not being caused by introduction of new animals or semen. These infections were tested to see if they were because of area movement of the disease, pig movement with in the barn, transport, insect carriers, or human carriers. In this study 83% of infections were considered lateral, the remaining 17% were caused by introduction of infected animal or semen. Area spreading was considered to be the cause of 52% of the lateral cases. Transport due to the removal of cull sows, boars or slaughter and feeder pigs, was strongly suspected to be the causes of 17% of the lateral infections. Insects were suspected in one case, while bio-security breaches were suspected in two cases. This study provides insight into systems that have PRRS negative pigs brought into them. PRRS is then caused mostly by area, meaning vicinity to other operations and transport of dead animals.
Transmission Of Pathogens: We Veterinarians Should Change OurTune!
Posted in: Air Filtration, Pork Insight Articles by admin on March 31, 2004 | No Comments
It has been commonly assumed that the leading cause of disease transmission among animal herds is by contact of infected animals with non infected animals. But since this theory has been so accepted there is little attention payed to other possible causes of disease transmission such as airborne spreading. This article describes instances where diseases have been transferred not by the introduction of infected animals but by aerial transmission. Foot and mouth disease in the UK was found to be caused by the introduction of infected animals in 5% of cases and 79% because of local spreading. In 1997 the epidemic of hog cholera was only found to be spread because of introduction of infected animals in 3% of the cases. Local spreading was the cause of the disease spreading in 36% of the cases. Porcine reproductive and respiratory syndrome is another common disease among swine herds. In an outbreak in Quebec, 44 cases of PRRS were detected, but the multiplier herd had never tested positive for PRRS meaning that none of these cases were because of the introduction of an infected animal. Enzootic pneumonia is another common disease worldwide in the pig industry. A outbreak in Quebec was from a completely negative herd source leading to the belief that the herds were infected by area spread, or neighborhood infection. These events suggest that aerosol transmission should be considered as a likely source of disease spreading along with infected semen and introduction of infected animals.
PRRS in Review: What do we know and where do we go?
Posted in: Air Filtration, Pork Insight Articles by admin on March 29, 2004 | No Comments
Since the discovery of the PRRS virus there have been large strides in further understanding it and how it moves within a swine herd, from one herd to another and how it is diagnosed. This article by Scott Dee summarizes the facts that we currently know about the PRRS virus. Most pigs are infected with the PRRS virus from an infected sow. As sows give birth to piglets they become infected while lactating and run the risk of transferring the virus to older pigs who were not born with PRRS but grouped together with these PRRS positive pigs. Understanding this transmission sequence is crucial in achieving a stabilized herd, meaning there is no chance of transmitting the virus from sow to sow or sow to pig. The work to eliminate PRRS from swine herds has been well documented, despite this completely PRRS negative herds still become infected with the virus. This was originally blamed on introducing PRRS positive pigs into a PRRS negative population and the use of semen that my contain the PRRS virus. But further research has proven that PRRS can also be transmitted by fomites, insects, in transport trailers and aerosols. Many new forms of diagnosing PRRS have become available since the discovery of the virus including the IDEXX ELISA, polymerase chain reaction and nucleic acid sequencing. Although each method still has drawbacks such as it can be difficult to interpret data for an individual pig.
New Information on Regional Transmission of PRRSV and its Potential Impact on Swine Farm Biosecurity Protocols
Posted in: Air Filtration, Pork Insight Articles by admin on August 31, 2003 | No Comments
One of the biggest challenges faced in pig biosecurity is the spreading of the PRRS virus by aerosols. Currently biosecurity protocols are successful at preventing the introduction of other swine pathogens, such as transmissible gastroenteritis virus, but they have limited, if any efficacy against PRRSV. This was mostly because no one knew exactly where the virus was coming from and it was believed that once the disease left the host it was harmless to others. The purpose of this article is to summarize attempts to identify regional vectors and routes of PRRSV spread and discuss how these new data may impact future biosecurity protocols and facility designs on swine farms. It has been proven that PRRSV can be transmitted by biological vectors like mosquitoes and house flies. Also both mosquitoes and flies have shown that PRRS can remain viable in their GI tracts. Tests done that invovled infected flies who were released and then baited and trapped at various distances found that flies caught as far as 2.3 km away were PCR-positive. Another possible transmitter of the PRRS virus is transport carriers. Pigs are shipped long distance to slaughter and also come into close contact with other pig herds and cross international and state boarders. Little information exists on this subject so a test was designed to find the potential risks involved with the spreading of PRRS through transport trailers. The experiment involved four treatments: Treatment 1 consisted of a manual scraping of the interior to remove soiled bedding. Treatment 2 consisted of bedding removal, washing, and disinfecting. Treatment 3 consisted of bedding removal, washing, disinfecting as described; however to simulate cold weather conditions, trailers were then frozen overnight at -20 0 C and allowed to thaw. Treatment 4 consisted of bedding removal washing, disinfecting and drying. Following each treatment, naive sentinel pigs were housed in trailers for 2 hours. Only treatment 4 prevented pigs from becoming infected with PRRSV. Scott Dee believes biosecurity for PRRS comes down to four things 1. Having a naive source of breeding stock and semen. 2. Insuring that the interior of the transport vehicle is always dry in every case. 3. Controlling the risk of insect entry. And 4. Controlling the risk of PRRSV-contaminated aerosols. Dee goes on to propose questions that should be asked about biosecurity such as: Should we have different protocols based on season? Do we need to reconsider barn design? Can we still live with naturally ventilated facilities? and other questions that should be addressed as we battle the PRRS virus.
Accurate screening for porcine reproductive and respiratory syndrome
Posted in: Air Filtration, Pork Insight Articles by admin on August 30, 2003 | No Comments
The PRRS virus is very detrimental to a swine herd and can be very costly to producers. Being able to test for PRRS is crucial, the IDEXX HerdChek* PRRS 2XR test kit which can detect antibodies from European and North American strains of PRRS in pig serum, is a good tool for producers to have for early detection of the PRRS virus. This tool has a 1:40 dilution of serum with 30,30,15 minute timing. The IDEXX HerdChek provides a fast, accurate, sensitive and easy to use tool due to the incorporation of diagnostically important epitopes representing the two major type strains of PRRSV.
Evaluation of mosquitoes, Aedes vexans, as biological vectors of porcine reproductive and respiratory syndrome virus
Posted in: Air Filtration, Pork Insight Articles by admin on August 29, 2003 | No Comments
This study tries to determine if mosquitoes are able to transport the PRRS virus form one swine herd to another. To achieve this the study looked into the duration of viability and the site of PRRS virus within the mosquitoes. The researchers evaluated if PRRS could be transported to a susceptible pig by mosquitoes who had fed on an infected pig 7-14 days earlier. The tests consisted of 100 mosquitoes that fed on a pig which was experimentally induced with PRRS. The mosquitoes were then kept alive under lab conditions. 10 mosquitoes were then collected a various time intervals: at 0 hour (h), 6 h, 12 h, 24 h, 48 h, 72 h, 5 days (d), 7 d, 10 d, and 14 d post-feeding. Samples of various mosquito parts were taken to determine if they were PRRS positive. Infectious PRRS that would infect pigs was only found on the gut homogenates of mosquitoes collected at 0 and 6 hours post feeding. The second experiment involved 30 mosquitoes who feed on PRRS infected pig and then after 7, 10 and 14 days after feeding the mosquitoes were allowed to feed on a PRRS negative pig. The PRRS negative pig did not contract the virus nor did the mosquitoes have any traces of PRRS on them. This lead to the indication that mosquitoes are not a likely source of biological vectors for PRRS.
The Financial Impact of PRRS Virus
Posted in: Air Filtration, Pork Insight Articles by admin on August 28, 2003 | No Comments
Some of the financial losses from a PRRS infection are more deaths, poor growth performance, increases of other diseases, and the use of more medications and vaccines. Outbreaks among the sow herd have been estimated to be around $250 per sow and as high as $302 per sow. The costs involved with persistent infections in the breeding herd or growing pigs are difficult to quantify, some authors believe it to be around $6.25 to $15.25 per pig. Following a PRRS outbreak the chances of other diseases infecting the herd can be increased significantly, which can cause huge losses to producers. Most producers spend more money on diagnostic testing and herd monitoring after their herd becomes infected. Budget analysis can provide a simple method for estimating the cost of the diseases on a farm and help justify the money spent developing control strategies.
Costs of PRRSV in Commercial Production
Posted in: Air Filtration, Pork Insight Articles by admin on August 27, 2003 | No Comments
The PRRS virus is a serious problem for hog producers but it is often difficult to understand the economic impact of PRRS on a herd. In order to acquire a solid understanding of the impacts of a PRRS outbreak, researchers looked at hog operations in the mid-west United States to gain data. Sites were ranked based on there PRRS infection rates: 0 – consistent production of PRRS negative pigs, 1 – PRRS infected herds with no sign of PRRS in the nursery, and 2 – PRRS positive pigs in the nursery. Pig flows were tracked over seven months, and nursery data and finishing data was collected. Analysis of the data was able to provide a good look at the cost of PRRS, stating that: Income per pig weaned for status 0 was $42.64, for status 1 $40.46 and for status 2 it was $35.57. Also the PRRS status of each site moved linearly with wean-finish performance.