Economic Impact of Porcine Reproductive and Respiratory Syndrome (PRRS) on Nursery and Grower-Finisher Production in Ontario08 May 2014
Researchers at the University of Guelph in Canada have calculated the total cost associated with PRRS outbreaks in Ontario - based on the cost of mortality and impaired performance - to be up to C$4 million annually or C$4.50 per nursery pig and C$1.87 per grower-finisher pig in the year following an outbreak. The data were presented at the 33rd Centralia Swine Research Update in January 2014.
Porcine reproductive and respiratory syndrome (PRRS) is considered to have a major economic impact on the pork industry in Ontario and worldwide, reported Radu Zorzolan and colleagues at the University of Guelph, Canada.
However, very few studies have been conducted using production data from nurseries and grower-finisher barns associated with herd outbreaks of disease to determine the financial impact of PRRS on these stages of production.
The objective of this study was to estimate the economic impact in nursery and grower-finisher stages associated with a PRRS outbreak using production records provided by six Ontario pork production enterprises. Cost was estimated to reflect the impact of PRRS on the total Ontario pork industry as well as on a per pig basis.
Methods and Materials
The cost of a PRRS outbreak for the nursery and the grower-finisher phase was determined by combining the total cost due to increased mortality, reduced growth and changes in the feed conversion ratio.
The time period used in this cost estimate was divided into two six-month periods, i.e. the first six months following the outbreak, and the six- to 12-month period after the outbreak.
The Guelph data suggest that the effect of PRRS differs in these two time periods.
Likewise, the cost model was stratified by the type of pig flow (all-in/all-out vs. continuous) because our investigations of cases showed a difference in the effect of PRRS between these two types of flow. In addition, the incidence of PRRS (assumed to be 10 per cent) was included in the cost model.
As a general principle, production losses were based on a summary of actual production data from documented outbreaks of PRRS in six Ontario pork production enterprises.
The production loss attributable to PRRS was calculated as the difference between the average production parameter during a specific phase of the outbreak (i.e. the first or the second six-month period of the outbreak), relative to the six-month period before the outbreak.
In Ontario during the study period, the total annual numbers of pigs raised in continuous flow (CF) and all-in/all-out (AIAO) nurseries was estimated to be 2.08 million and 3.33 million, respectively, for a total of 5.41 million per year. In the finishing barns 3.12 million market hogs were produced in a CF system and 1.68 million per year in AIAO. Total number of grow-finish pigs raised in both systems was estimated to be 4.80 million per annum.
A total cost associated with reduced nursery performance for herds experiencing PRRS outbreaks based on the cost of mortality, reduced feed efficiency and slower growth rate was estimated to be C$2,485,831 per year or for an affected farm this represents a loss of C$4.50 per nursery pig in the year following a PRRS outbreak.
For the grower-finisher stage, the total cost of PRRS outbreaks for Ontario in a year was estimated to be C$1,464,012, or for an affected farm this represents a loss of C$1.87 per grower-finisher pig in the year following an outbreak.
The one study (Neumann et al., 2005) in the literature that is constantly quoted estimates the cost of PRRS in the US to be approximately US$560 million.
The Neumann paper identified a cost of $6.01 and $7.67, for a nursery pig and a grower-finisher pig, respectively. This estimate for nursery impact was based on two operations and the grower-finisher performance was based on data from six operations.
In the American study, no distinction was made regarding the type of flow but the Guelph data suggest the impact is less in AIAO type operations than in continuous flow. It is possible that the outbreaks documented in the American paper were caused by a more pathogenic strain of virus or that the herds involved had other health issues that complicated the picture.
It is well recognised that an important way that PRRS exerts its effect on the health of a pig is by reducing the pig’s immunity to other respiratory diseases so, depending on what other diseases are also present, the impact of PRRS in the grower barn can be severe.
The cost estimates in the Guelph study are much lower than the American study primarily because the Ontario case herds that provided the data were impacted to a lesser extent with respect to mortality, growth rate and feed efficiency in the nursery and the grower-finisher phase than reported in the small number of herds used in the American calculation.
In the Canadian cases, the PRRS outbreak affected the farrowing herds as well as the other production phases. Obviously, different scenarios might produce a more severe disease in the grower-finisher stage.
For example, if a PRRS-positive grower-finisher barn operated as CF and received feeder pigs from a PRRS-negative source, then one would expect a much worse outcome than the model predicts. However, such a scenario is relatively rare compared to the situation documented in the six production systems used to create the baseline for this study.
The calculation of the cost of PRRS for nursery and grower-finisher production based on Ontario data and accounting for different production practices and recognising the change in effect over time may be a more accurate estimate than is currently available and as such may be useful in making decisions regard ing implementing PRRS control programmes.
Acknowledgments: This work was supported by Agribrands Purina Inc., OMAF/MRA and OSHAB.
Neumann E.J., Kliebenstein J.B., Johnson C.D., Mabry J.W., Bush E.J., Seitzinger A.H., Green A.L. and Zimmerman J.L. 2005. Assessment of the economic impact of porcine reproductive and respiratory syndrome on swine production in the United States. J. Amer. Vet. Med. Assoc. 227: 385-392.
Zorzolan R., Z. Poljak, K. McEwan and R. Friendship. 2014. The economic impact of porcine reproductive and respiratory syndrome (PRRS) on nursery and grower-finisher production in Ontario. Proceedings of 33rd Centralia Swine Research Update.