New PRRS Study: Impact Remains High

A new study just released estimates the total tab to the industry at $664 million annually, based on a review of production records from 80 breeding herds and grower pig closeout data on more than 600 groups of pigs over the past 3-5 years.

Joe Vansickle, Senior Editor

September 20, 2011

8 Min Read
New PRRS Study: Impact Remains High

For years, the swine industry has remained burdened with the staggering $560-million price tag for production losses associated with porcine reproductive and respiratory syndrome (PRRS). But the real news is this — since the 2005 economic study was released, and despite numerous advancements in research and production schemes, the cost of this disease continues to rise.

A new study just released estimates the total tab to the industry at $664 million annually, based on a review of production records from 80 breeding herds and grower pig closeout data on more than 600 groups of pigs over the past 3-5 years.

That analysis also includes expert opinions from 26 swine veterinarians who provide services to 2.4 million U.S. sows — roughly 45% of the nation’s sow herd. Information for the report was collected from October 2009 to October 2010.

Economic Breakdown

Lead researcher Derald Holtkamp, DVM, Iowa State University, says the economic impact breaks down to an annual loss of $302.06 million for the breeding herd, $52.19/breeding female or $2.36/pig weaned.

The majority of the loss in the breeding herd — $300.4 million — reflects the lost revenue resulting from weaning 8.3 million fewer pigs. Table 1 lists productivity estimates from a survey of expert opinions and production records for breeding herds by PRRS category.

For the growing pig herd, the estimated annual loss amounts to $361.8 million or $65.52/breeding female.

Accounting for higher mortality, lower average daily gain and a decrease in the percentage of pigs sold to the primary market meant 9.9 million fewer pigs, and 2.41 billion fewer pounds of pork sold annually, resulting in a total loss in potential revenue to the pork industry of well over $1 billion.

With PRRS, costs were lowered significantly to $361.8 million because fewer pigs and pounds of pork were produced during the grower period, thereby partially offsetting the
lost revenue.

Table 2 depicts wean-to-finish productivity estimates. Both breeding herd and wean-to-finish estimates stem from a survey of expert opinion and production records for growing pigs by PRRS category.

Combined losses in the breeding and growing pig herds accounted for 9.9 million fewer pigs lost during the nursery and grow-finish phase, and 2.41 billion pounds of pork, carcass weight, sold per year in the United States.
The total direct cost of PRRS to the U.S. national breeding herd and growing pig herd of $664 million annually breaks down to a drain of $1.8 million/day.

One major difference in the two PRRS studies, 2005 vs. 2011, is in the allocation of losses between the breeding herd and the growing pig herd. Losses in the breeding herd accounted for 12% of the total cost of PRRS in the 2005 study, compared to 45% in the current analysis, Holtkamp explains.

“If you put that $560 million into today’s dollars, it would be about $40 million higher, so inflation explains about 40% of the difference in the cost of PRRS,” he adds .

Other reasons for higher costs in the 2011 study may be due to changes in the prevalence of PRRS virus, virus strains and the severity of disease they cause, and other pathogens that have emerged since 2005, such as porcine circovirus type 2.

Biosecurity, Outbreak Costs

Based on the expert opinion survey, animal health costs tack on another $140 million annually due to PRRS. The annual biosecurity and other outbreak-related costs attributed to PRRS were estimated to be $191.86 million and $145.82 million, respectively. Biosecurity costs include installation of air filtration systems, truck washes and other changes to transportation, added showers, changes in pig flow, etc. Total additional costs were pegged at $477.79 million annually, putting the cumulative cost of the disease at more than $1 billion/year when added to production-related losses, Holtkamp reports.

In addition to the expert opinion survey, the report also drew on a literature review related to the economic impact of PRRS virus and data compiled from swine health surveillance by USDA’s National Animal Health Monitoring System (NAHMS) of pork producers.

Surprising PRRS Results

With the magnitude of the PRRS problem, Holtkamp says it was also surprising to learn that 28% of U.S. breeding herds reported being PRRS virus-free (designated BH-A in Table 1) based on the expert opinion survey.

The current data also revealed that 42% of all breeding females were in herds that had a PRRS outbreak in the 12 months prior to Oct. 1, 2010 (BH-B and BH-D).

For the year-long study ending Oct. 1, 2010, 60% of weaned pigs in the United States were identified as negative at placement. That means that 40% of pigs were positive at placement (GP-C).

Of the 60% of pigs that were negative, 58% of them became infected before they were marketed, Holtkamp points out.

Further, in breeding herds that had an outbreak, productivity and economic losses in the 12 months after the outbreak were greater when the herd was PRRS virus-free before the outbreak, compared to herds that were PRRS virus-infected, he says.

Also, the timing of infection in growing pigs affected how the pigs performed, the study showed. Productivity was better in groups of growing pigs that were infected after weaning (GP-B), than those infected before weaning (GP-C).

“In 2005, the number of PRRS-positive pigs at placement would have been a lot higher, and that has been one of the advancements as reflected in this study. We have gotten a lot better at being able to wean groups of negative pigs,” Holtkamp says.

Using the survey of expert opinions to signify regional differences, 19% of herds were negative for PRRS (BH-A) in the east, 35% in the Midwest and 28% in the west.

Definitions for PRRS status of breeding herds and growing pig herds are provided in the sidebar below.

PRRS Elimination Plans

A net present value (NPV) economic analysis was performed to evaluate the costs and benefits of PRRS virus elimination from individual herds. This is the first analysis that accounts for the more severe negative production and economic consequences of a PRRS outbreak when a PRRS virus-free herd becomes reinfected, Holtkamp points out.

The analysis evaluated two approaches to eliminating PRRS virus from a herd: complete depopulation and repopulation (CDR) with PRRS virus-free breeding animals and herd closure and rollover (HCR).

Using HCR as the method of elimination, breeding herds needed to remain free of PRRS from four months to 26 months to break even on the cost of elimination. The exact time to break even depended on the PRRS status of the breeding herd when the elimination was started, how often negative pigs were weaned, when the breeding herd was infected and how much it cost to eliminate the virus.

When CDR was the method of elimination, the time needed to remain free of PRRS to break even ranged from 18 to 83 months.

The cost of CDR was significantly higher, ranging from $250 to $350/breeding female vs. $10 to $40/breeding female for HCR.

PRRS Still Has Upper Hand

Despite all of the innovations and advancements made in PRRS research and application of control strategies at the farm level, the virus appears to still be winning the battle and may be winning the war, Holtkamp says.

“Not only have we not beat PRRS, I think we are losing ground. In order to beat this disease, the only strategy that is going to be successful is to get ahead of it by eliminating it faster than we have outbreaks,” he says.

The dozen or so regional PRRS control projects are a way to get that job done. That is, dealing with the disease on a regional/community level, addressing routes of transmission and local risk factors, and getting people working together and sharing information, he says.

The research team that compiled the PRRS economic impact study consisted of Holtkamp, James Kliebenstein, Jeff Zimmerman, DVM, Tiffany Yoder, Chong Wang and Chris Mowrer, Iowa State University; Eric Neumann, DVM, Massey University (New Zealand); Hans Rotto, DVM, Innovative Agricultural Solutions, Ames, IA; Paul Yeske, DVM, Swine Veterinary Center, St. Peter, MN; and Charles Haley, DVM, USDA.

PRRS Herd Classifications Ease Analysis

The objectives of the National Pork Board’s $80,000 funding of the porcine reproductive and respiratory syndrome (PRRS) economic impact study were to estimate the current costs of PRRS virus in the United States and to estimate the cost of eliminating the virus.

The goal was to provide data useful to local, state and national control/elimination efforts and for allocation of resources for swine health research.

Lead researcher Derald Holtkamp, DVM, of Iowa State University devised four categories of breeding herds based on their PRRS status. Definitions for these classifications were developed by the American Association of Swine Veterinarians (AASV) and the U.S. Department of Agriculture PRRS Coordinated Agricultural Program (PRRS-CAP).

The four categories included herds that met the AASV/PRRS-CAP criteria for category I (positive unstable) or category II (positive stable) breeding herds, while PRRS virus-free breeding herds included those that met the classification criteria for category III (provisional negative) or category IV (negative).

Holtkamp explains that once herds were classified based on whether they were PRRS virus-infected or PRRS virus-free, breeding herds (BH) were further categorized by whether they had an outbreak within the last 12 months. Thus, the categories are:

  1. BH-A: herds that were PRRS virus-free, no outbreak;

  2. BH-B: herds with an outbreak in the last 12 months but were PRRS virus-free before the break;

  3. BH-C: herds that were PRRS virus-infected but had not experienced an outbreak for at least 12 months; and

  4. BH-D: herds that had experienced a PRRS outbreak within the last 12 months and were PRRS virus-infected when the outbreak occurred.

The PRRS category assigned to a breeding herd could change over time.

Since most growing pigs are confined in static groups rather than in a continuous-flow environment, Holtkamp’s team of researchers devised a simpler means of placing growing pigs into three categories, according to their PRRS status at placement and at the time of marketing, as follows:

  1. GP-A: growing pigs that were PRRS negative at weaning and remained negative until marketing;

  2. GP-B: growing pigs that were PRRS negative at weaning, but became infected prior to marketing; and

  3. GP-C: growing pigs that were PRRS positive at weaning and remained positive throughout the growing period.

Standardizing the terminology has helped clarify disease status for cleanup programs, and the breeding herd and growing pig classifications have been adopted for use in a number of the regional PRRS control projects, Holtkamp says.

About the Author(s)

Joe Vansickle

Senior Editor

Joe, a native of Indiana, is a graduate of the University of St. Thomas in St. Paul, MN, with a bachelor’s degree in journalism. He worked on daily newspapers in Albert Lea, MN and Fairmont, MN, before joining the staff of National Hog Farmer in 1977. Joe specializes in animal health issues, federal regulations, environmental concerns, food safety and writing about the swine veterinary community. Joe has won several writing awards from the Livestock Publications Council. In 2002, he earned the Master Writer Program Award from the American Agricultural Editors’ Association.

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