And exactly what does a clean calving pen look like?
During and since completing my Nuffield study entitled “Alternatives to Antibiotics in Agriculture”, I identified that husbandry practices on livestock farms, ruminant and monogastric, increase stress and infective bacterial challenge on livestock without farmers realising so. I found that farmers, when they can see and understand a problem, are very good at fixing those issues. They are not so good when it comes to problems they can’t see or understand. Farmers don’t see dead animals as a result of antibiotic resistance; they see dead or sick animals due to, for example, E.coli infections.
In my attempt to understand the effect of Anti-Microbial Resistance (AMR) within agriculture, I struggled to understand:
- Why broiler chicken farmers in Australia, America and Canada got equal or better feed conversion ratio’s and less mortality than we do in the United Kingdom (UK), even though they only clean and disinfect their sheds once a year, whilst we clean and disinfect after every crop, every 39 to 43 days? They would place a new crop of chicks onto the previous crops’ dirty litter. We would place new chicks in clean disinfected freshly littered sheds.
- Why pigs farrowing in old, at first sight dirty, farrowing buildings had healthy piglets, whilst brand new setups where piglets are born into almost sterile conditions had mortality rates of up to 25%?
- Why dairy cows are susceptible to mastitis infections whilst beef cows aren’t?
- Why lambs born inside, in clean and disinfected sheds get infections and scour whilst lambs born outside in muddy fields don’t?
- Why calves born in nice warm disinfected sheds with clean bedding get bacterial infections that cause scour whilst those that calve outside in the rain, wind and on muddy grass don’t.
By studying both diagnostic tools for agricultural use and types of bacterial infections of livestock, I realised that AMR in agriculture is as much of an issue in terms of Biocides as Antibiotics. In other words, bacteria have developed strategies to cope with disinfectant use on farm to as well as antibiotic use. As farmers we seem to be unaware of this scenario.
Animals don’t live in sterile conditions; neither should we keep them in conditions conducive to bacterial infections. There is an assumption within agriculture that when we use disinfectants, we reduce the bacterial challenge our animals face. But, this is an assumption that is NOT based on evidence. My Nuffield study led me to the conclusion that if we are to develop strategies on farm that allow for prudent use of antibiotics, then we have to generate evidence of what bugs are actually causing the infective issues we are trying to resolve. Not all bacteria that cause infections in our animals can be treated with antibiotics. I was amazed to find that of the fifteen common mastitis causing micro-organisms’ in dairy cows, only four can be treated effectively by antibiotics. When our dairy farmers detect clinical mastitis, the first call to action is often to treat the animal with an antibiotic. If the bacteria causing the infection can’t be destroyed by the said antibiotic anyway, the farmer is wasting time and money and increases the risk of AMR by treating.
The assumption that surfaces are clean post disinfection needs challenging. What I have found, based on evidence generated on farm, is that, post disinfection; concentrations of disease causing bacterial colonies have intensified and proliferated on the surfaces that come into contact with our livestock and farmers / farm workers. So, for example, piglets in disinfected farrowing buildings are being born onto surfaces where there are concentrations of disease causing bacteria three days before the immunoglobulins in the sows colostrum can build an antibody mediated immune defence within the piglet to fight bacterial infections. This happens either because bacterial colonies present on the surfaces have become resistant to the disinfectant, or, due to biofilms protecting these bacteria from the disinfectant. New born calves, lambs, chicks, even smolt fish all face the same fate when surfaces become dominated by disease causing bacteria. The need for antibiotic treatment is fuelled by the disease causing bacterial infections that take hold prior to the formation of the animals antibody mediated immune defence.
By using on farm diagnostic tools, farmers are able to develop strategies based on them being able to visualise the root cause of their infection problems. They can see which bacteria are infecting their animals. They can decide, quickly, based on veterinary protocol, if they should treat the animal with an antibiotic or not based on evidence. They can make an informed decision, based on evidence, as to the efficacy of their hygiene protocols in reducing the bacterial loading and hence stress on their animals. Farmers however don’t tend to be microbiologists. They need simple tools to enable them to generate the information they need to limit bacterial infection stress on their animals.
Piglets born onto slats with a high concentration of infective bacteria
Cow close to calving. High concentrations of infective bacteria found in bedding sand.
By Aled Rhys Davies