Herd Health/Management

The Impact of PRRS On Cost of Production

Four pork industry analysts used a combination of techniques and data to project the current annual cost of porcine reproductive and respiratory syndrome (PRRS) to the U.S. swine industry.

The USDA-National Animal Health Monitoring System (NAHMS) conducts a survey every five years to provide a valid demographic and descriptive survey of the U.S. swine industry. The most recent survey of pork production operations was in 2000. The next NAHMS survey of hog operations will be in July 2006, and the results will be published in March 2007.

PRRS was a specific focus of the 2000 NAHMS survey. It showed that PRRS was the second-most often reported health problem in breeding herds (21.4%).

Using a case study approach, the NAHMS group surveyed information on farms across the United States to estimate the prevalence of PRRS-affected farms by production phase.

Also, a Delphi-type survey of industry personnel (primarily swine veterinarians) familiar with PRRS was conducted to help with estimating the annual cost of the disease. A Delphi survey is a structured group interaction process that provides opinion collection and feedback, validated on a national scale for detailed information on PRRS.

In the breeding-farrowing phase, the economic impact of PRRS was calculated to be $74.16/litter on affected farms. Of this amount, $45 was derived from a reduction in the number of pigs weaned/litter, and $29.16 was due to reduced farrowing rate.

The cost of PRRS in the nursery was pegged at $6.01/head on affected farms. This amount was comprised of $3.58 for increased pig mortality, $1.17 for reduced feed conversion and $1.26 for reduced average daily gain.

In grow-finish, the cost of PRRS was projected at $7.67/head on affected farms. Of this total, $3.23 was due to increased mortality, $3 for reduced feed conversion and $1.44 was attributed to reduced average daily gain.

Overall, based on NAHMS information and the size of the U.S. pig industry, the annual cost of PRRS is projected to be $66.75 million in breeding-farrowing, $201.34 million in the nursery, and $292.23 million in finishing. Combined, the total is $560.32 million.

A much higher cost of PRRS was arrived at when the Delphi survey data was summarized. The annual cost of PRRS was estimated at $111.12 million in breeding, $244.53 million in the nursery and $406.15 million in finishing for a total impact of $761.80 million.

The study was completed using pork checkoff funds.

Researchers: Colin Johnson and John Mabry, Iowa Pork Industry Center; James Kliebenstein of Iowa State University; and Eric Neumann, DVM, formerly of the National Pork Board. Contact Johnson by phone (515) 294-2340 or e-mail ColinJ@iastate.edu.

Bacterial Product Cuts Antibiotic Use, E. coli Problems

Beneficial bacteria, cultured in a research laboratory, hold promise as an alternative to antibiotics in providing a cost-effective treatment for postweaning E. coli problems.

The patented bacteria that is harvested, often referred to as commensal bacteria, is produced naturally in the pig.

The new treatment approach involves colonizing a baby pig's intestinal tract with a mixture of beneficial bacteria, which are designated as RPCF (recombined porcine continuous-flow).

The field trials consisted of six geographically separated farms (five nursery sites in Kansas, Minnesota and Missouri, and one wean-to-finish operation in Iowa), with a history of high mortality from K88 and F18 strains of E. coli.

On those farms, piglets were orally administered a 2 ml. dose of the cultured bacteria within 24 hours of birth, and monitored through the nursery phase.

A total of 21,467 piglets were treated with RPCF. A similar number of piglets served as untreated controls.

On five of six farms, the beneficial bacteria reduced the impact of E. coli at a fraction of the cost of antibiotics. Mortality in RPCF-treated pigs decreased by an average of 2.6% over untreated control pigs (Table 1). Differences in mortality were not observed for the different treatment groups on one Minnesota farm.

When projected to an annual basis, the economic benefits from decreased medication costs and mortality averaged $24,663/farm.

Lead researcher Roger Harvey, DVM, with the Agriculture Department's Agricultural Research Service in College Station, TX, concludes that although RPCF is not a “silver bullet,” research results suggest it may serve as a valuable intervention method, when used with other management practices, to lessen the effects of E. coli. RPCF also offers a viable alternative to antibiotics in pig production, thus curbing concerns about antibiotic resistance.

The treatment is not yet approved for commercial use. Harvey says it may take two years or more before it is licensed and commercialized. He projects the product will cost in the range of $0.50 to $1/dose.

Researchers: Roger Harvey, R.C. Anderson, K.J. Genovese, T.R. Calloway and D.J. Nisbet, Southern Plains Agricultural Research Center. Phone Harvey at (979) 260-9259, fax (979) 260-9332 or e-mail harvey@ffsru.tamu.edu.

Table 1. Effects of a Defined Culture of Commensal Bacteria of Porcine Gastrointestinal Tract Origin* on Mortality and Medication Costs Due to Escherichia coli (E. coli)
Location (No.) Mortality plus cull, % Medicine cost/pig, $
Farm A (Missouri)
Control (3,242) 9.06 0.70
RCPF (10,402) 2.80 0
Difference 6.16 0.70
Farm B (Missouri)
Control (6,318) 3.33 0.11
RCPF (4,900) 2.54 0
Difference 0.79 0.11
Farm C (Missouri)
Control (3,068) 3.30 0.28
RCPF (3,127) 2.45 0
Difference 0.85 0.28
Farm D (Iowa)
Control (1,331) 9.00 0.40
RCPF (1,288) 4.20 0
Difference 4.80 0.40
Farm E (Kansas)
Control (350) 1.50 0.10
RCPF (250) 0.90 0
Difference 0.60 0.10
Farm F (Minnesota)
Control (1,500) 0.40 4.0
RCPF (1,500) 4.0 0
Difference 0 0.40
*RCPF refers to recombined porcine continuous-flow.

Crowding Reduces Performance, Floor Type Doesn't

Crowding is known to affect the performance of grow-finish pigs. But research at the Prairie Swine Centre (PSC) in Saskatoon, Saskatchewan, discredits the belief that pigs need more floor space if housed on partially slotted floors.

PSC scientists placed four blocks of grower pigs averaging 81 lb. on full or partially slotted flooring at three levels of space allowance: 4.1 sq. ft./pig, 5.81 sq. ft./pig and 8.40 sq. ft./pig. The lowest space allowance was discontinued after the grower phase.

Average daily feed intake was not affected by floor type or floor space allowance in grower or finisher phases.

Average daily gain tended to be less on partially than on fully slotted floors during the grower phase (Figure 1), but in general did not differ during the finishing phase of production.

As expected, pigs tended to grow slower on the lowest floor space allowance than the two other space allowances.

Average daily gain tended to be reduced by crowding during the finishing phase. PSC researchers estimate that this represents a lost opportunity of about $1/hog marketed at $0.65/lb.

Researchers: T. Done, S.M. Hayne and H.W. Gonyou, Prairie Swine Centre, Saskatoon, Saskatchewan, Canada. Phone PSC at (306) 373-9922, fax (306) 955-2510 or e-mail Ken.Engele@usask.ca.

Developing Better Oral Vaccines For K88 E. coli

Infection with enterotoxigenic E. coli (K88, now known as F4) causes postweaning colibacillosis (PWC) in 4- to 6-week-old pigs. Current vaccine strategies provide maternal immunization, conferring protection to piglets. But this protection wanes at around 5-6 weeks of age, leaving piglets susceptible to infection.

Antibiotics are the main line of defense against E. coli, but an effective vaccine may provide better protection while decreasing the use of antibiotics.

Researchers at the Vaccine and Infectious Disease Organization (VIDO) in Saskatoon, Saskatchewan, are trying to develop effective oral vaccines against PWC by inducing mucosal immunity in the small intestine.

Oral vaccination is being tested using a recently developed gut-loop model, which is based on the surgical creation of independent intestinal segments (loops) in piglets. All loops remain within the animal for four weeks. Various vaccine formulations are administered into the loops, and local immune responses to vaccination are assessed for four weeks.

Having access to multiple loops (6-8 loops/animal) allows VIDO researchers to assess multiple doses and vaccine formulations within the same animal, eliminating environmental fluctuations.

Using the model, it was found that the vaccine induced the strongest immune response when the animal had the highest level of K88 receptors present in its small intestine.

This has implications for the development of future vaccines, as it demonstrates that the K88 status of the animals is more important to vaccine effectiveness than the dose given or the adjuvant used.

Researcher: Volker Gerdts, Vaccine and Infectious Disease Organization, Saskatoon, Saskatchewan, Canada. Contact Gerdts by phone (306) 966-1513, fax (306) 966-7478 or e-mail volker.gerdts@usask.ca.