This article summarizes the initial findings of a research project entitled "Etiology, Virulability, and Immunity of Swine PMWS: Genetic-Environmental Interactions" and publishes it as a BPEX (British Pig Raising Committee) from a scientific research to a practical series of articles. The seventh article.
This article summarizes the initial findings of a research project entitled "Etiology, Virulence, and Immunity of Swine PMWS: Genetic-Environmental Interactions." Prior to the advent of the PCV2 vaccine, pigs in almost all pig farms in the UK were infected to varying degrees with PMWS (porcine polymorphic syndrome after weaning). However, for some unknown reasons, some farms are more affected by the disease and some are relatively minor. The purpose of this research project carried out by the Royal Veterinary College is to find out why there is such a difference.
Study involved pig farms
Type blood test results confirmed that all pig farms visited had PCV2 virus or antibodies to the virus (see below). If one of the tests in each sample of a farm is positive for PCV2, the farm is considered to be positive for PCV2.
Pig farmer's impression of the severity of PMWS
Assessing the proportion of PMWS infected on a farm is a challenging task because of the limited time spent on each farm. Therefore, the study included the impression of the farmer as a supplement to the data.
In order to ensure that the farmer's record of PMWS is indeed PMWS, the researchers asked the farmer to answer relevant questions in order to assess their understanding of the disease. The misclassification decision tree was used in the study to remove those farms that did not meet the criteria from the analysis.
According to the farmer's instructions, the severity of the disease changed from 2001 to 2008. The number of heavily affected pig farms decreased, but the total number of affected farms increased (Figure 3). This shows that since the pandemic phase (2001-2003), the prevalence of the disease has changed.
In 2008, pig farm owners evaluated clinical symptoms and data showed that there were differences between different farms. In areas where the symptoms of weaned pigs were reported, growing pigs also reported symptoms. However, this inevitable symptomatic link was not found in finishing pigs. From the analysis, the farmer's impression of the severity of the clinical symptoms of the disease can be summarized as two points:
Incidence factor 1 (MF1): proportion of affected weaned and growing pigs
Incidence factor 2 (MF2): proportion of affected finishing pigs
Assessment of severity of farm-level PMWS
The proportion of pigs affected by PMWS alone is not sufficient to assess the severity of the disease on the farm because the disease affects many performance parameters.
After analyzing several performance indicators, the presence or absence of different pathogens on the farm, and the incidence factors, there was a strong correlation between the three variables. The three variables are:
1. Mortality after weaning
2. Pork PCV2 virus infection rate in pig farms
3, the incidence of weaning / growing pigs.
It was found that only PCV2, but not any other pathogens, was associated with the proportion of weaned/growth pigs affected and post-weaning mortality. This relationship appears to be a measure of the severity of PMWS.
To summarize these three variables, a score of 0 to 10 can be given for the severity of PMWS on the farm.
The score results can be divided into the following categories:
The PMWS score calculator [click here] can be found on the BPEX website.
This PMWS score can be achieved:
1. Assess the severity of PMWS infection in a farm
2. Discussion for PMWS prevention and control, and
3. Monitoring of the PMWS prevention and control measures taken over time.
The Royal Veterinary College will use these severity scores to:
1. Identify risk factors for PMWS and its impact
2. Assess the efficacy of different PCV2 vaccines, and
3. Develop a tool to determine what is the most effective and cost-effective PMWS control solution (for specific farms)
to sum up
The characteristics of wasting disease in finishing pigs appear to be different from those in weaned/growth pigs
Although the severity is declining, PMWS remains a significant problem among UK weaned pigs and growing pigs
There is a tool that has been developed to compare the severity of PMWS between different farms, and will help develop a control plan
More information
The results of this study have been published: Alarcon, P et al., 2011. Assessment and quantification of multisystemic debilitating syndrome after weaning in pig farms. Preventive Veterinary Science, 98:19-28.
Anti-Allergic Agents,Chlorphenamine Tablets 4Mg
NOUVASANT PHARMhealth LTD. , https://www.nouvasant.com