By Michelle Kromm, DVM, MPH, MAM, DACPV
Food Forward, LLC
Minneapolis, Minnesota
In poultry production, we are masters of measurement. For decades, we have used data collection systems to help us track input costs and bird performance. Key performance indicators (KPIs) are established and monitored using these data systems and, ideally, strike a balance between input costs and bird performance. Typically, several different KPIs are used to assess how a complex is functioning overall and suggest where there are opportunities for improvement. This approach acknowledges the interconnectedness of input costs, bird performance and financial sustainability.
If we were to focus on a singular KPI to determine success, it would likely lead to financially unsustainable decisions. For example, if our only goal was to make cheap feed with no consideration for feed conversion or daily gains, what would be the overall cost impact on the system? Alternatively, we could myopically focus on formulating feed using premium ingredients, but in an adverse economic environment, would that be the most fiscally sound decision?
And yet, we can fall into the trap of focusing on a single metric. Doing so within the biological systems in which we work leads to false assumptions about where opportunities for improvement exist.
Given our collective panache for measuring bird performance with a stat sheet that would make most baseball statisticians jealous, how did we end up with one number to reflect the daily work that goes into antimicrobial stewardship? As an industry, why don’t we use this multifaceted, measurement-driven mindset and apply it to antimicrobial stewardship?
The ‘single metric’ problem
The poultry industry has led the animal-protein space in reporting antimicrobial use (AMU) for years, yet we’ve cornered ourselves with this singular metric when discussing our comprehensive approach to antimicrobial stewardship.
When we cite our AMU, we typically refer to the ratio of milligrams of antimicrobials used to the kilograms or pounds of protein produced (mg drug/kg protein). It is a simple way to capture AMU, but it isn’t particularly good at providing a holistic view of antimicrobial stewardship.
This single metric measures a single action — the administration of an antimicrobial — and misses the layers of prevention we’ve established and constantly refine to reduce the need for antimicrobial intervention.
It’s akin to looking at your live cost without knowing market weight, feed cost per ton, feed conversion, yield, etc. It is a number without context, operating on the assumption that low is good and high is bad, and with inadequate information on how to impact the outcome being measured.
Antimicrobial stewardship versus antimicrobial use
In addition to being limited to one non-descriptive number, stakeholders across the food economy have adopted the AMU ratio as a proxy for antimicrobial stewardship, which is the set of actions focused on minimizing the use of antimicrobials and selecting the most appropriate one when it becomes necessary, all while minimizing impacts to animal and human health.
Without the additional context provided by a stewardship program, we tend to assume that if your AMU ratio is lower than another company’s, you are obviously a better steward of antimicrobials. If your AMU ratio increases, then your system is clearly overusing antimicrobials.
Using the AMU ratio in this way helps simplify a multifaceted topic of societal interest. Our brains like simplicity and are constantly seeking ways to conserve energy by forming patterns from the information they receive. An easy pattern for the AMU ratio would look like this:
- Down (lower AMU ratio) = good/responsible/judicious
- Up (higher AMU ratio) = overuse/abuse/irresponsibility
I hope you can think of many scenarios in which these ratios change in ways unrelated to stewardship of antimicrobials. For example, disruptions in supply chains experienced during natural disasters or with emerging diseases can cause changes in AMU, as many farms have experienced recently with avian metapneumovirus.
Additionally, how AMU is impacted by treating a flock depends largely on the age at which your birds get sick. AMU ratios for treatment at different ages would differ because antimicrobial administration is based on weight, which is unrelated to stewardship, assuming antimicrobial parity.
How would we interpret the difference in the AMU ratios in this scenario? We would celebrate the producer whose birds were infected young as having practiced better stewardship, yet chide another producer whose birds were challenged at an older age — all because the first producer’s AMU ratio would be lower.
Taken together, although measuring antimicrobial use can be an important data point in an antimicrobial stewardship program, it is not the sole indicator that determines whether a producer/veterinarian/system has a robust antimicrobial-stewardship program.
Measuring antimicrobial stewardship
Producers spend most of their efforts on activities that align with antimicrobial stewardship. From conditioning litter between flocks to practicing biosecurity and, of course, administering vaccines, producers mitigate disease risk through prevention, the bedrock of antimicrobial stewardship.
Veterinarians perform routine disease surveillance to ensure that preventative health programs are optimized for disease control. They assess disease exposure with serology, perform necropsy surveys and review condemnation rates to determine whether a preventative-medicine program is effective.
When flocks do get sick, diagnostic workups are conducted to determine the underlying cause. If there is a bacterial component that warrants treatment, antimicrobial stewardship principles necessitate using a sensitivity test to determine the appropriate treatment choice.
All these processes provide an opportunity to measure our stewardship. Other activities listed below could each be captured as a number to describe better the investment being made in preventative medicine and, therefore, antimicrobial stewardship:
- Investments in biosecurity
- Vaccination rates
- Number of diagnostic tests run annually
- Rate of utilization or spend on prebiotics, probiotics, etc.
Countering the negative
If treatment rates increase due to health challenges for which preventative controls don’t exist, such as a new variant of infectious bronchitis virus, the increase in AMU associated with treating secondary bacterial infections could be viewed negatively. Presenting corollary increases in diagnostics, including necropsy, pathogen identification and bacterial sensitivity testing, would be an important counterbalance to that negative view.
Additionally, establishing preventative-medicine metrics would facilitate a comprehensive view of the work done to ensure that an increase in AMU at the complex, system or industry level wasn’t due to lapses in stewardship practices.
Bringing it together
In closing, although metrics are essential for tracking progress and maintaining accountability in the poultry industry, relying solely on AMU as a singular proxy for stewardship is problematic. AMU trends can change for many reasons unrelated to stewardship practices, ranging from disease pressure to shifts in production practices, and do not reflect the full scope of preventative strategies embraced by the poultry industry.
True antimicrobial stewardship is multifaceted and best captured through a broader lens that includes on-farm practices, preventative medicine and animal-health outcomes. Poultry producers across the country are already practicing many aspects of antimicrobial stewardship, and it’s vital that we recognize and support their efforts without narrowing the narrative to a single, oversimplified metric.
Editor’s note: The views expressed in this article are solely those of the author.
