#02-223

Complete

Date Full Report Received

03/05/2004

Date Abstract Report Received

06/23/2009

Investigation

Institution:
Primary Investigator:
Co-Investigators: Alice Green, Colin Johnson, Eric Bush, Eric Neumann, John Marby

This study used a combination of techniques and data sources to arrive at the annual estimated cost of porcine reproductive and respiratory syndrome on the United States swine industry. By using a case study approach and comparing production parameters on PRRS-affected farms to the same parameters on non-affected (or recovered) farms, costs of the disease were summarized for the breeding-farrowing phase, the nursery phase, and the growing-finishing phase of production. The economic affect of PRRS in the breeding-farrowing phase
was calculated to be $74.16 per litter. Approximately 60% ($45.00 per litter) of this cost was derived through a reduction in the number of pigs weaned per litter with the remaining 40% ($29.16 per litter) coming from a
reduction in farrowing rate. The cost of PRRS in the nursery production phase was estimated to be $6.01 per head on an affected farm. Nursery pig mortality was responsible for the majority of this cost ($3.58 per head) with less impact on feed conversion efficiency ($1.17 per head) and average daily gain ($1.26 per head). The economic affect of PRRS in the growing-finishing production phase was estimated to be $7.67 per head on affected farms. Similar to the nursery production phase, mortality was responsible for the majority of the cost ($3.23 per head) with lesser, but still important impacts on feed conversion efficiency ($3.00 per head) and average daily gain ($1.44 per head). In order to extrapolate the data collected through the case study into a national cost aggregate, information collected by the USDA-National Animal Health Monitoring System (NAHMS) in their study of swine production in 2000 was used to estimate the prevalence of PRRS affected farms in the U.S. industry. The NAHMS data indicated that approximately 44.91 percent of breeding females in the U.S. were in PRRS positive herds. Assuming that once a herd is found to be positive, it will remain positive for an extended period, and that approximately one-third of breeding females are replaced each year, it was estimated that 15% (44.91% divided by 3) of breeding herds experience a clinical outbreak of PRRS each year. With the U.S. inventory of breeding females standing at around 6 million, one can then calculate that approximately 0.9 million litters per year are affected by PRRS at a cost of $40.50 (0.9 million times $45.00 per affected litter) million annually. To calculate an aggregate cost of PRRS in the nursery and growing-finishing phases, NAHMS data was again utilized. NAHMS reported in 2000 that 32.16% and 38.10% of U.S. pigs were in PRRS positive nurseries or finishers, respectfully. United States slaughter pig throughput traditionally averages about 100 million pigs per year. This allows one to calculate the estimated cost of PRRS in U.S. nursery pigs to be $201.34 million per year and finishing pigs to be $292.23 million per year. Combining the aggregated costs of PRRS to the breeding herd, nursery herd, and finishing herd yields an annual estimate of $560.32 million borne by U.S. pork producers.
As a comparison to the case study approach for estimating an average annual cost of PRRS to the U.S. swine industry, a Delphi survey of swine disease experts (primarily swine veterinarians) was conducted. A variety of information was collected from the respondents in an effort to estimate the impact of PRRS on specific production parameters as well as the duration of a typical outbreak and their estimates of the prevalence of the disease. When this data was summarized and aggregated to a national level, a somewhat higher impact of PRRS on the industry was reported. The impact of PRRS on the breeding herd was estimated to be $111.12 million per year, on the nursery herd to be $244.53 million, and on the finishing herd to be $406.15 million for a total impact of $761.80 million.