Financial Analysis of Herd Status and Vaccination Practices for Porcine Reproductive and Respiratory Syndrome Virus, Swine Influenza Virus, and Mycoplasma hyopneumoniae in Farrow-to-Finish Pig Farms Using a Bio-Economic Simulation Model

Abstract

This study aimed (1) to quantify the effects of positive status and vaccination practices for porcine reproductive and respiratory syndrome virus (PRRSv), swine influenza virus (SIV) and Mycoplasma hyopneumoniae (MHYO) on the profitability of farrow-to-finish pig farms and (2) to examine the financial impact of vaccination status in PRRSv and SIV positive farms. Data from 56 Irish farrow-to-finish pig farms were used for this study. Production effects associated with herd status for the three pathogens were incorporated into the Teagasc Pig Production Model (TPPM), a bio-economic stochastic simulation model for farrow-to-finish pig farms. In the analysis, farms negative (-) for either PRRSv, SIV or MHYO were assumed as baseline when presenting results for farms positive (+) for each pathogen. While all MHYO(+) farms used vaccination against the pathogen, not all PRRSv(+) or SIV(+) farms vaccinated against the disease. For all scenarios, a 728-sow farrow-to-finish farm with weekly farrowing batches was simulated. Financial risk analysis was conducted by Monte Carlo simulation within the TPPM using the Microsoft Excel add-in @Risk. Mortality rates, feedstuff costs and price per kg of meat produced were included as input stochastic variables and annual net profit was set as stochastic output variable. Positive farms sold fewer pigs and produced less kg of meat than negative farms and had increased feed usage during the weaner and finisher stages. Variable costs increased in positive farms due to increased feed costs, more dead animals for disposal and healthcare costs. Annual mean profit was lower by 24% in vaccinated PRRSv(+), 14.6% in unvaccinated PRRSv(+), 36.7% in vaccinating SIV(+), 12.8% in unvaccinated SIV(+), and 41% in MHYO(+) farms. Negative farms were first order stochastically dominant over positive farms, indicating that for a given level of profit, the financial risk is lower by avoiding respiratory pathogens. Similarly, unvaccinated farms were second order stochastically dominant over vaccinating farms suggesting that farms that do not vaccinate are less affected by the disease. Results from this study provide further evidence to encourage farmers to undertake improved disease control measures and/or to implement eradication programs.

Keywords: financial risk; herd health status; pig production systems; respiratory diseases; whole-farm stochastic budgeting.

Figure 1

Flow diagram describing data sources and bio-economic modeling process followed to simulate effects associated with different prevalence of pleurisy and lung scars on slaughter pigs on farm performance and profitability. Three scenarios were simulated for a 728 sow farrow-to-finish farm.

Figure 2

Cumulative probability distribution showing the influence of herd status [i.e., negative (–) or positive (+)] and vaccination practice [i.e., vaccinated or unvaccinated] to (A) Porcine reproductive and respiratory syndrome virus [PRRSv(–) not vaccinating, PRRSv(+) vaccinating sows (vacPRRSv) and PRRSv(+) not vaccinating (unvacPRRSv)]; (B) Swine influenza virus [SIV(–) not vaccinating vs. SIV(+) vaccinating sows (vacSIV) and SIV(+) not vaccinating (unvacSIV)] and (C) Mycoplasma hyopneumoniae [MHYO(–) not vaccinating vs. MHYO(+) vaccinating weaner pigs] on farm net profit.

Figure 3

Box and whisker plots of the annual mean net profit, 5th and 95th percentile and the interquartile ranges of farms differing in herd status [i.e., negative (–) or positive (+)] and vaccination practice [i.e., vaccinated or unvaccinated] to Porcine reproductive and respiratory syndrome virus [PRRSv() not vaccinating, PRRSv(+) vaccinating sows (vacPRRSv) and PRRSv(+) not vaccinating (unvacPRRSv)]; Swine influenza virus [SIV() not vaccinating vs. SIV(+) vaccinating sows (vacSIV) and SIV(+) not vaccinating (unvacSIV)] and Mycoplasma hyopneumoniae [MHYO() not vaccinating vs. MHYO(+) vaccinating weaner pigs] on farm net profit.