Rethinking the Stink About Antibiotics in Manure

Thanks to the Soil Science Society of America and Susan Fisk for this great article. Antibiotics and manure. You probably don’t think of them at the same time. But across North America, manure and antibiotics often share the same pile. Antibiotics ward off diseases. Low levels of antibiotics are also often fed to livestock to improve their growth. However, much of the antibiotics fed to livestock goes to waste--literally. “Often, 90% or more of the antibiotic is excreted, according to previous studies,” says Francis Zvomuya. “Manure containing these is then used as fertilizer on crops.” Zvomuya is a researcher at the University of Manitoba in Winnipeg. And that’s not the end. Once applied with manure to crops, those antibiotics are in the natural environment, mixing with air, soil, and water. This can lead to antibiotic-resistant bacteria, a public health concern across the world. One way to prevent such a chain reaction is to make sure antibiotics are broken down before they reach the field, for example, via composting or stockpiling. The question is, “How quickly are these antibiotics breaking down during such handling?” says Zvomuya. Traditionally, researchers have tried to answer this question by adding antibiotics to antibiotic-free man

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2 thoughts on “Rethinking the Stink About Antibiotics in Manure

  1. This may have already posted but I don’t see it.
    This article asserts the concerns about antibiotic resistance from consistent feeding of low dose antibiotics to farm animals are based in field applications of manure. I was under the impression that of just as much or greater concern is that those populations of rapidly reproducing bacteria directly leave the farm via air / wind, via humans, via birds and other wildlife, via waterways and discharge, via clothing and vehicles, etc. Are these factors a concern? Why are people allowed to apply low dose antibiotics over time to non-human animals, but not humans? Why do we not apply similar standards of care and concern for the general population? If living conditions and diets are poor enough to require consistent feeding of antibiotics then the problem is clearly human management and it imperils the animal, the nutritional quality of meat, the lives of workers and surrounding communities of humans and non-humans as well as waterways and all down steam and downwind and down the food chain.

    Another question: is the “composting” of manure in these studies composting (pile coming to heat, turned, etc) or is it digested in a manure lagoon or similar structure?

    Thank you!

    1. Hi Graham,
      I think the authors are on the same page as you noting that “Once applied with manure to crops, those antibiotics are in the natural environment, mixing with air, soil, and water. This can lead to antibiotic-resistant bacteria, a public health concern across the world.” Low-dosing animals with antibiotics has been a way of increasing weight gain and growth and wasn’t necessarily done to offset poor living conditions. Because of the issue of antibiotic resistance over the past couple years the FDA has been working on getting farmers to reduce their use and to use them only for treating illness. Some large companies are now advertising that they have given up the daily use of antibiotics. So things are changing.

      You can read more about the study by clicking on the link at the end of the article. I took a quick look and it seems that the manure was composted not digested in a manure lagoon. The study article contains all the details on how they did that.

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