• Question: Why are antibiotics used in battery farming? How does this make the animals grow faster?

    Asked by 536anta47 to Ceri, Marikka, Matt, Rob, Sally on 12 Nov 2014.
    • Photo: Sally Cutler

      Sally Cutler answered on 12 Nov 2014:

      Good question! Yes they can help growth rate in livestock and were used extensively for many year this way. It is now banned in Europe, but not every where around the globe. Afraid this has really helped to fuel the resistance problems.

    • Photo: Robert Hampson

      Robert Hampson answered on 13 Nov 2014:

      Antibiotics are used in industrial farms for two reasons.
      1) Prophylaxis (they want to prevent bacterial infections in the livestock)
      2) Growth stimulation (the animals produce more meat or milk for less feed)

      Bacterial infections can spread through livestock and make them very ill. This essentially reduces the farmers profits. The farmer must still feed the animals but the ill animals cannot be used for milk or meat. Even when the animals have recovered they don’t produce as much milk or meat over their life time as they would have done if they had never been ill. Continual doses of antibiotics effectively stop this being a risk.

      We don’t really know why antibiotics help animals to grow faster. It has been hypothesised that they affect the bacteria in the gut of the animal meaning less of their food is diverted to the growth and maintenance of gut bacteria and more is used in the growth of the animal. However, we don’t really know the exact mechanism.

    • Photo: Ceri Dare

      Ceri Dare answered on 13 Nov 2014:

      Antibiotics are used in battery farming to stop the animals becoming ill – because they are crowded together, stressed and in bad conditions, infections spread very quickly. So giving the animals antibiotics all the time so they can’t become ill and maybe die makes more profit. But then the bacteria get used to the antibiotics and become more and more resistant. The resistant bacteria can spread to humans, and make humans ill with hard to treat infections.

      Also, antibiotics at a low dose make animals put on weight faster. We don’t really know why, but this was discovered when animals were fed on a low dose of waste left over from making antibiotics. Again, this makes bacteria evolve resistance to antibiotics, and these bacteria spread to humans and make them ill.

      This is one of many reasons why I think it would be better if everybody ate less meat!