This is our Friday rubric: every week a new Science Page from the Bob Morrison’s Swine Health Monitoring Project. The previous editions of the science page are available on our website.
In today’s Science Page Kaci Way, Jessica Higgins, Todd Wolff, Derald Holtkamp and Lynette Holeman share the results of a study evaluating the benefit of influenza vaccines in finishing pigs.
Influenza A virus (IAV) is a growing concern among swine practitioners. This is due to swine influenza’s large economic impact on the industry, its zoonotic potential, and its ability to rapidly mutate.1 Following the implementation of a vaccination program for IAV, it is important to assess whether the expected economic benefit is being achieved and whether vaccination should be continued based on the evaluation. The objective of this study was to evaluate the economic impact of an autogenous influenza vaccine used in finishing pigs with a pre-post analysis utilizing closeout data
Material & Methods
The study took place in a medium-sized system that is Mycoplasma hyopneumoniae negative with variable porcine reproductive and respiratory syndrome virus (PRRSV) status located in the Midwest United States. Closeout data utilized for this analysis included multiple lots of pigs started from October 1, 2020, until February 28, 2022. The pre-vaccination group included lots of finishing pigs started from October 1, 2020, until February 28, 2021. The post-vaccination group included lots of finishing pigs started from October 1, 2021, until February 28, 2022. To address the potential confounding effect of seasonality, only lots started between October through February were included in this study. There were 47 lots of finishing pigs included in the pre-vaccination data and 40 included in the post-vaccination data. The pre-vaccination group was vaccinated with a single dose of a commercial killed influenza vaccination given at weaning or 8-9 weeks of age at the labeled dose per pig. The post-vaccination group was given a single 1 ml dose of a five-strain autogenous influenza vaccination formulated specifically for finishing pigs at 8-9 weeks of age.
The closeout data was extracted and analyzed using Excel. Potential confounders and outliers were explored using box and whisker plots of the average weight at placement, average finishing weight, and days to market. Frequency distributions and box and whisker plots were created for key performance indicators (KPIs), including average daily gain (ADG), feed conversion (FCR), mortality rate, and feed per head. The economic analysis was performed to estimate a relative benefit: cost ratio using a fixed time-to-market production and economic model.
Results & discussion
The average finishing mortality was 7.52% for the pre-vaccination group and 5.66% for the post-vaccination group. ADG was 1.96 for the pre-vaccination group and 2.02 for the post-vaccination group. The pre-vaccination FCR was 2.85, and the post-vaccination FCR was 2.70. Administering an autogenous influenza vaccine to pigs at 8-9 weeks of age that costs $0.52 per pig placed was beneficial to this swine production system with a $10.54 increase in profit per pig placed for the post-vaccination group and a benefit-to-cost ratio of 20.3:1 (Table 1). In conclusion, the use of an autogenous influenza vaccine in finishing pigs demonstrated that it is not only beneficial to health and production metrics but also proved to be economically favorable.
1. Influenza viruses – diseases of swine – Wiley Online Library. (n.d.). Retrieved November 16, 2022, from https://onlinelibrary.wiley.com/doi/10.1002/9781119350927.ch36