Antibiotics in Agriculture: We Can’t Afford It.

NZ nature

A snapshot from our Massey University Albany campus.

I am fairly certain my housemate saved my life that day. It was the first week of graduate school and she found me delirious, dehydrated and with a temperature above 40°C. Overconfident, I babbled about having the flu but being fine, the futon had hurt my back and that I just needed some water. It turned out I had a progressed kidney infection. That is how I came to start my graduate course in bacterial evolution; alongside courses of antibiotics, prescribed to combat the bacteria ravaging my internal organs.

We often take antibiotics for granted. But every day there are more and more people for whom antibiotics don’t work. Hundreds of thousands now die each year from bacterial infections that can no longer be treated with these life saving drugs. A recent report estimated that by the year 2050, more people will die of antibiotic resistant infections each year than from cancer (O’Neill 2016).

That is a truly scary prospect. We may still be able to avoid this fate but it will take real changes in the way we use these precious medicines. We have over used antibiotics in a deeply irresponsible way and it is time for us to reassess our values. You and I, lawmakers, doctors and farmers must all carefully consider the sacrifices that we are willing to make to save human lives. What is a life worth?

For global antibiotic awareness week this year I want to focus on antibiotics in agriculture. This is not what we generally think of first when we discuss this issue but it should be. According to the Food and Drug Administration, in the US, 80% of all antibiotics are used in agriculture (2009 FDA report).

How can that be? For reasons that are still not clear to science when low doses of antibiotics are given to the farm animals they increase the amount of meat that they put on their bones (2012 Review). This use of antibiotics is called “growth promotion” and it is no longer allowed in Europe or New Zealand. For those places where it is still permitted it is a huge boon for farmers who are looking for ways of producing cheap meat. Bigger animals mean bigger profits for individuals and corporations who are trying to feed the world meat products.

Not long ago the New Zealand Veterinary Association (NZVA) vowed “by 2030 New Zealand will not need antibiotics for the maintenance of animal health and wellness.” In the same report the NZVA also proudly declared that New Zealand is already the third lowest user of antibiotics for animals in the OECD (Organisation for Economic Co-operation and Development) (Hillerton) (Fig. 1). This sort of statistic is enough to swell the heart of any red blooded Kiwi soul. We are proud of our beautiful rolling hills and our happy grass fed sheep and cattle. “Of course we are doing well,” we sigh contentedly, “we are clean and green and so naturally we are miles ahead of places like the US” (ranked 28/30).

Antibiotics ag

Figure 1. Antimicrobial use in humans and agriculture by mg/Kg biomass in OECD countries, 2012 (Hillerton).

Unfortunately, as with many a national myth, this one does not hold up to closer inspection. The first tip off is the metric that is being used by the NZVA; Antibiotic use in milligrams per kilogram of biomass (mg/Kg). To be clear, the NZVA did not invent this reporting measurement, they are simply following a very cleverly opaque convention. By reporting the mg/Kg of biomass we benefit simply by being a country that has a lot of large animals to put in the denominator, a single chicken weighs a little less than 2 kg on average but a single cow weighs 160 times that. Any country in the OECD with a high proportion of cattle and sheep is going to have a lower reported mg/Kg, even if every chicken and pig in the nation is being force fed unnecessary antibiotics in it’s feed each day. As it happens, Cattle and Sheep, which are generally (but not always) free range in NZ, make up 98% of the weight of the animals that we raise for food production each year (Fig. 2).

Bio mass NZ

Figure 2. Animal biomass in New Zealand broken down by animal type.

Poultry and Pigs combined are 2% of the animal weight we put in our denominator but these two groups consume 34% or 22,000 kgs of antibiotics sold for agriculture each year. That is phenomenal to me. Ultimately, we may look good by this measure but we should not pat ourselves on the back for simply having a lot of cattle. We are still pouring huge amounts of antibiotics directly into the feed of many of the poultry and pigs here in NZ.

Why do we do it? This use of antibiotics is called “prophylactic use”. Essentially, we deliver antibiotics to these animals in their water or feed in order to prevent them from getting sick. This is common practice when animals are being kept in less than ideal conditions. Stressed, over crowded, close quartering of small animals is cheaper for farmers but these are also ideal conditions for infections to spread. Constant prophylactic antibiotic administration is one way of keeping these animals healthy.

“Who cares?” you may say, “I am no battery hen!”

Antibiotics Res spreads

Figure 3. Antibiotic use in one environment can affect antibiotic resistance rates in many other environments (adapted from Andersson and Hughes 2014).

I was recently involved in the drafting of the most recent white paper on ‘Antimicrobial Resistance – Implications for New Zealanders’ from the Royal Society of New Zealand. This is an excellent source of NZ relevantdata on this topic and I can recommend it. Two important points are that antibiotics that go into agricultural production are not isolated there and they don’t simply go away. They assert pressure on bacteria in the soil to become more resistant to those antibiotics (Fig. 3). If these are pathogens we can become infected when we ingest food that has been treated with antibiotics. The second point raised by the RSNZ report is that the rates of antibiotic resistant pathogens such as methicillin-resistant Staphylococcus aureus (MRSA), carbapenemase-producing Enterobacteriaceae and beta-lactamase resistant Enterobacteriaceae in New Zealand are already on the rise.

According to a 2015 study published in the Proceedings of the National Academy of Science, New Zealand is using more antibiotics in food animals per Km2 than many other OECD countries (Fig. 4). This means that we are running the same risks in terms of the affect of these antibiotics on the bacteria that infect us as any of our less favourably ranked OECD colleagues. This also means we still need to do better!

Select Counties Use-01

Figure 4. Antibiotic use in animals by land or per person in select OECD countries.

None of us wants our friends or loved ones to be the next person in hospital who will be told that the antibiotics aren’t working because the bacteria are already resistant to everything we have. It’s a nightmare scenario. What are we willing to give up to avoid the post-antibiotic era?

-I encourage lawmakers in New Zealand to take antibiotic use seriously and regulate agricultural use. This should include labelling antibiotic use in the foods we see in the supermarket.

-I implore farmers to reconsider their practices if they are using antibiotics for anything other than saving lives. Let us strive towards practices that will eliminate such use.

-As a consumer, ask yourself what cost we are all really paying for the cheap meat we find in the supermarket. Can you afford it at this price?




About drhhnz

Microbiology, Evolution and Bacteriophages. Lecturer, Institute of Natural and Mathematical Sciences. Massey University. Superhero name: Microbiology Girl. Auckland, New Zealand · Twitter: drhhnz
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3 Responses to Antibiotics in Agriculture: We Can’t Afford It.

  1. Very nice article! You uses very good graphics to explain it.

  2. drhhnz says:

    Thanks! Some of these are adapted from my Fascination Science lecture!

  3. Pingback: Research for AGRI : News – January 2018 – Research4Committees

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