Escherichia coli (thankfully shortened to E coli!) is an imposing name for an imposing bug! As we have discussed in these columns several times previously this bug, or more correctly this bacterium, is the cause of many losses in commercial egg layers.
E coli is everywhere! E coli has an affinity for living in animal intestines (including humans!). As a result, it is disseminated widely in the environment, via poultry litter, faeces, washings from poultry houses and droppings from wild birds i.e. in any material contaminated with faeces. Although there are many strains of E coli some are more invasive and pathogenic than others. Often particular sites may have their own specific ’resident’ strain. The bird itself has some in-built resistance to stop E coli from entering the bloodstream and causing the all too typical egg peritonitis, blood poisoning (septicaemia), tissue damage and death. A trigger factor is always needed to give the E coli a helping hand to open doors in the birds defence system and allow the organism in. The usual entry points are the intestines, throat, windpipe or oviduct, where the bug may be sitting harmlessly.
Trigger factors
The triggering factors are many and varied. In the respiratory tract this may be excessive dust, high ammonia or humidity, or infections such as mycoplasmas or viruses (especially infectious bronchitis or TRT). In the intestines this may be direct damage caused by coccidiosis, digestive upset due to nutritional problems or even a worm burden. In the oviduct this can be following all sorts of stresses (e.g. alteration in lighting pattern, vermin or people disturbance, certain diseases) that allow the oviduct and ovary to get out of phase with each other with infection often being sucked up via the vent.
Weight of challenge
In addition to all these potential helping hands the effects of E coli also depend on the numbers game i.e. the ’weight’ of the challenge. The birds environment, litter quality in the house, wet muddy areas on range or dirty drinker systems can all present the birds with a hefty slug of bacterial soup. These can overwhelm the birds immune system especially if this is already compromised by various stresses and strains from disease, through heavy red mite infestation, to poor management.
Question 1: The first question most frequently asked by producers is "How can we treat outbreaks of mortality on our farm?" As producers know their treatment options are very limited. Chlortetracycline via the drinking water is the only licenced option which dose not require eggs to be withheld from sale during or after treatment. Even the ’nil withdrawal’ period is rumoured to be under threat!
Question 2: This always leads to the second important question. "How can we prevent problems in the first place?"
Answers? We have discussed many of the options on control and prevention in previous articles, but to summarise:
- Reduce disease challenge by good programmes of biosecurity, vaccination regimes and effective worming and red mite strategies.
- Reduce general stresses by good management, preventing feed interruptions or lighting problems, avoiding overcrowding, and maintaining good, predictable routines in all you do.
- Reduce bacterial challenge by maintaining good litter quality, excellent water hygiene and fencing off or drainage of any standing water or puddles on range.
- Consider strategic feed medication, where appropriate, and under strict veterinary supervision.
- Consider homeopathic options available, which may help to improve the birds immune response or reduce the effects of challenge (although at least one of the authors of this article is pretty sceptical about their use!).
- Consider specific E coli vaccination. This is an option being turned to with increasing frequency. As with the more well known vaccines given during rear, the idea is to encourage the bird to produce protective antibodies, hopefully causing any offending E coli to ’bounce off’ the birds primed immune system and not gain entry to cause damage. There is one commercially available E coli vaccine designed for broiler breeder hens, but there is increasing interest in so-called ’autogenous’ vaccines. These can be manufactured by approved laboratories ’tailor made’ to specific farms, being based on the specific E coli strains causing problems on your site. The manufacture and licencing of these vaccines is complex but your veterinary surgeon can advise you on this approach. Like any other vaccine, these autogenous vaccines are another brick in the wall of building protection against E coli challenge. If other areas mentioned in this article are not addressed then the wall may crumble or the challenge can wash over the top!
Conclusions
E coli challenges will always be with us. The key to success is reducing the frequency, severity, and effects of that challenge. Using some of the tricks mentioned in this article should help to prevent E coli from getting the upper hand on your site.
