Manure from Chinese pig farms contains both antibiotic residues and high concentrations of bacteria that are resistant to antibiotics, a new study published Monday by the Proceedings of the National Academy of Sciences. The study adds to evidence that antibiotics used by China’s pork producers pose health risks. The study, led by the Chinese Academy of Sciences, found there is a risk of antibiotic resistance moving into the bacteria that infect humans and make the resulting diseases more difficult to treat. James Tiedje, Michigan State University microbiologist, assisted in the study and said the Chinese were “quite forthcoming.” Antibiotic residues in pig manure was monitored at three Chinese pig farms. Tiedje said the study did not intend to single out China’s pig farms as antibiotics in pig manure is a worldwide problem, with similar findings already recorded in Europe. In China, Tiedje found more than 100 different resistance genes with levels 200 times higher than in manure from pigs that had never used antibiotics. They study also found that once manure leaves the farm, its potential for spreading antibiotic resistance to other surrounding bacteria in the environment is much diminished. Pork production with antibiotic use has been growing rapidly in China, where half of world’s pigs are grown for a country with a growing appetite for pork.

  • Mike_Mychajlonka_PhD

    Excellent paper!  I wonder how this work will impact the meat industry’s HACCP plans going forward.  I was also surprised at the shape of your Figure 1C, where no antibiotic or group of antibiotics was seen to predominate over the other.  I was also surprised by the persistence this paper demonstrated of antibiotic resistance genes upon composting.  This suggested, to me at least, that even if all antibiotic and heavy metal supplementation (in feed) were to stop immediately, antibiotic resistance genes would persist for quite some time.  It seems to me that such persistence would be of considerable interest to fruit and vegetable growers, include leafy greens.

  • 19Matty36

    Why doesn’t this surprise me?  China again?

    • Charles Qu

      At least China does not have that much Listeriosis, Dioxin contamination, nor prion viruses.

    • Bonewrath

      The report specifically says it isn’t singling this out as a “Chinese only” problem, but a worldwide issue with all farms using antibiotics. So “China again” is hardly a fair, or well-read comment on the article.

  • federalmicrobiologist

    Some interesting observations from the paper in PNAS by Zhu
    et al. :

    ‘In China, the use of antibiotics both for animal disease
    treatment and growth promotion is unmonitored, which often leads to high use,
    reflected by the high concentrations of antibiotic residues (hundreds of
    milligrams of tetracycline per kilogram) that are commonly detected in animal

    ‘Furthermore, the use of subtherapeutic levels of
    antibiotics in animal feeds causes an increase in antibiotic resistance traits
    in manure, manure-amended soils, and downstream river waters and sediments. In
    addition, metals are added to swine feed for growth promotion and disease
    control and may provide a long-term coselective pressure for antibiotic

    diversity and abundance of ARGs reported in this study is alarming and clearly
    indicates that unmonitored use of antibiotics and metals on swine farms has
    expanded the diversity and abundance

    of the
    antibiotic resistance reservoir in the farm environment.’

    ‘Pig manure, with its abundant and diverse ARGs and sheer
    volume, is a major source of resistance genes and as such a public health
    hazard.’ (1)


    By importing US-style industrial food animal production (IFAP)
    practices, China is creating the same kinds of problems with antibiotic
    resistance that are bedeviling the US.


    Bizarrely, in India, land of Hindus and Muslims, a Canadian
    corporation named Polar Genetics has recently signed a MoU with an Indian
    branch of the corporation to establish swine CAFOs in Punjab.


    Polar Genetics’ corporate officer’s tout that they are bringing
    ‘modern’ and ‘scientific’ principles to pig farming in Punjab, and from thence,
    to India as a whole. This ‘modern piggery’ business model will of course employ
    the glorified sharecropping that characterizes contract pig farmers in much of
    the US:


    ‘The company will enter into guaranteed buy back agreements with
    the farmers, who will not have to worry about marketing of the pigs once they
    reach maturity (average 100 kg weight) within a short span of five months. The
    company was also in the process of indentifying a site to set up its own pig
    slaughtering and pork processing plant, he [Dr Darshan Singh Ball, CEO of Polar
    Genetics India Pvt. Ltd.] added.’ (2)


    In other words, the Punjab farmers who buy into this scheme will
    have to go deeply in debt to purchase the piglets, and then the feed,
    buildings, antibiotics, and hormones required to maintain a CAFO. If (and
    that’s a big ‘if’) they can force their animals to achieve market weight in 5
    months, then they may get the payment promised by the Polar Genetics India
    operation. If they can’t meet the strict terms of the contract, then they get
    severely reduced payment for their animals, and face bankruptcy.


    Of course, where the feces and urine from such large numbers of
    pigs is to be disposed of is not really addressed. Even in the modern and
    advanced USA, in places like Iowa, where swine CAFOs are considered sacred
    places, mass quantities of fermented manure from CAFOs is dumped on fields as
    ‘fertilizer’,  and efforts by clean-water
    grassroots groups, and the EPA, to deter the practice are decried as  ‘unscientific’.


    In light of the fact that much of rural India lacks adequate
    sewage infrastructure for human use, are we to think that waste from hundreds
    of pigs is going to be adequately disposed of ? Somehow I doubt that Polar
    Genetics India will lend a helping hand when it comes to the proper disposal of
    the pig feces and urine generated from its contract growers. And this is Punjab
    we’re talking about, not Kamrar, Iowa. The heat can reach 117 degrees in
    Summer. So it’s not just pig urine and feces, it’s WARM pig urine and feces,
    that will need to be dealt with.


    I have a bad feeling about Polar Genetic’s proposed operations
    in Punjab. But it wouldn’t surprise me if R. C. Hunt of the US National Pork
    Producers Council, and other advocates of IFAP, are overjoyed……


    1.  Yong-Guan Zhu, et al.,
    Diverse and abundant antibiotic resistance genes in Chinese swine farms. PNAS
    2013 ; published ahead of print February 11, 2013, doi:10.1073/pnas.1222743110


    2. ‘Punjab to be made hub of piggery farming; MoU signed’, by Abhijit
    Prashar; Punjab, Febr. 12, 2103