Links between antibiotic use for growth promotion, cost and production methods

By Aerin Einstein-Curtis

- Last updated on GMT

Links between antibiotic use for growth promotion, cost and production methods

Related tags Antibiotic resistance

The cost of ending antibiotic use for animal growth promotion may be dropping depending on the way the animals are raised, says a group of scientists. 

The team, based at Princeton University and the Center for Disease Dynamics Economics and Policy tracked the economic factors involved with the use of antibiotics as growth boosters in animals, said researcher Aude Teillant.

“We initially decided to start working on the economics of AGP [antibiotic growth promoters] use in livestock because we found that the debate and the research on antibiotic use in animals was much focused on the potential impact on antibiotic resistance in humans (and in animals), but less so on the economics of antibiotic use in livestock,” ​she told FeedNavigator. “We wanted to study what's known so far about the economic benefits and costs of using AGPs as crucial information for policy-making.”

In their work, the group sought to establish the overall amounts of antibiotics that are used in livestock growth promotion and to quantify the costs of removing AGPs from use in several countries.

Challenges and questions

The group did have some challenges tracking down information on the use of antibiotics worldwide and linking the use to animal productivity, said researchers.

“First we estimate and map order of magnitude estimates of the volume of antimicrobials used in the animal industry worldwide in 2010 and the projected values for 2030,” ​they said. “A secondary objective is to estimate (at a high level) the economic value of antimicrobial consumption in the livestock industry.”

It can be challenging to find recent data on the use of antibiotics as growth promoters because there is a variation in animal responses based on age, type of animal, and hygiene or management conditions, they said. Also, earlier studies done in the 1980s tended to demonstrate a greater response to the use of AGPs than more recent work.

“A common explanation is that the growth response to antimicrobials is less important when nutrition, hygiene practices, the genetic potential of animals and health status of the animal herd or flock are optimal,” ​they said. “With drastic changes in the animal industry over the last 30 years in the [Organization for Economic Co-operation and Development] OECD countries, all of these key parameters have changed, potentially explaining the decrease in the efficacy of AGPs.”

Methods

Researchers examined and estimated use of antibiotics for growth promotion for cattle, pigs and chickens in either an extensive or intensive farming situation in 228 countries, they said.

“Coefficients of antimicrobial use per kilogram of animal for each type of livestock and for each system were estimated based on data from the European Surveillance of Veterinary Antimicrobial Consumption (ESVAC) and were subsequently applied to high-resolution maps of livestock population densities topredict the geographic distribution of antimicrobial consumption in food producing animals for the years 2010 and 2030,”​ they said.

Additionally, the group sought to use that information to set value ranges for the potential loss producers might see if the use of AGPs was banned in that country in two different situations – with growth results from older data and from new data – they said.

Results

The team determined that the global consumption of antibiotics by animals raised for food was about 63,151 tons in 2010 and is expected to increase by about 67% to 105,596 tons by 2030. In some countries the use rate is expected to far exceed that, said the scientists.

 “It is projected that the cumulative loss of global meat production resulting from a worldwide ban on AGPs would result in a decrease by 1.3% to 3% from its current level (1980s vs 2000’s scenarios), corresponding to a global loss in meat production value between USD $13.5 and USD $44.1 billion in the two scenarios respectively,”​ they said.

However, there were some unexpected data points in the results, said Teillant.  “We were indeed quite surprised by the data we found, because recent data tend to show a decrease in the productivity gains from using AGPs in pigs and poultry production, even if sound and reliable data are still lacking,”​ she added.

Additionally, the results weren’t the same for all of the farms or production systems, she said. With different management practices, such as improved biosecurity and sanitation, reducing densities or uses and all-in-all-out pig flow, producers could limit lost cost in production.

“A ban on AGPs would impact producers differentially, according to location, farm size, contracting arrangements and most of all production practices,” ​she said. “Countries such as Denmark did not observe significant losses in production and earnings when they stopped using AGPs, partly because they invested a lot in modern production systems with high hygiene standards and improved biosecurity in herds.”

Analysis of the broiler industry in Denmark, found that there has not been much effect from the ban on AGPs, researchers said. The mortality rate and average weight gain were not altered by the change and there was a minor increase in birds’ feed conversion ratio.

Similarly, results for bans of AGPs with finishing and weaning pigs didn’t cause large changes for finishing pigs, they said. But, weaning pigs did see a loss in growth rate, though total production for the swine industry increased.

The results seen in some countries, including Demark and Sweden, after bans on AGPs may offer guidance to others seeking to move in the same directions, Teillant said.

“This can be used to understand which kind of investments need to be done ideally before withdrawing AGPs to make sure that production systems will be resilient enough and that the potential losses will be mitigated when stopping AGP use,”​ she said.

What’s next?

Although the group’s project covered potential economic results from the limiting of antibiotic use in animal production, there are areas where more work is needed, said Teillant.

Future work with the topic could seek to refine the initial findings and give a more specific picture for different regions or types of farms, she said. Additionally, there could be value in repeating or running new experiments looking at the growth effects of antibiotics in animal production to offer a more up-to-date data set.

“There is a lack of recent data - both in pig and poultry production - to assess the current growth response to AGPs; redoing studies similar to the early studies that established the growth benefits from AGPs would be very interesting to assess how this growth response changed,”​ she said.

One study​ along those lines looked at the use of antimicrobials in poultry production and found minimal effects from removing AGPs of two farms, she added.

Source: OECD Food, Agriculture and Fisheries Papers

Title: The Economic Costs of Withdrawing Antimicrobial Growth Promoters from the Livestock Sector

DIO: 10.1787/5js64kst5wvl-en

Authors: Ramanan Laxminarayan, Thomas Van Boeckel, Aude Teillant

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