New approach for enteric disease in broilers

A product originally aimed at helping producers control salmonella in laying flocks is proving effective in boosting the intestinal health of broiler flocks.

The management of intestinal health continues to present challenges to UK broiler operations. What has undoubtedly changed however is the desire to use fewer antibiotics and the emergence of real alternatives with the potential to complement or some cases replace traditional medication regimes.

The impact of pathogenic bacterial challenge is well recognised in broilers. Enteritis is thought to account for a 20-30 points deterioration in feed conversion, as well as further financial losses due to downgrades. The costs of additional management and also treatment compound the bottom line effect. We note that on many farms, one course of antibiotic treatment does not seem to clear the problem up and after a few days a further course is prescribed.

Overgrowth of Clostridium perfringens and release of toxins is known to play a key role in the spectrum of conditions that range from dysbacteriosis to necrotic enteritis. In order to develop a strategy for managing C perfringens which does not rely on antibiotics, we need to understand how the environment in which bacteria thrive can be modified to reduce their impact.

Competitive exclusion

Following research into salmonella control using Aviguard, we began to understand and record the real impact it demonstrated on a broader spectrum of intestinal diseases. It contains over 200 strains of bacteria known to be present in normal healthy chicken intestine and works by “competitive exclusion”.

This is a process where beneficial bacteria colonise the intestine and, thereby, exclude pathogenic bacteria. Such effects have been demonstrated many times in challenge studies using treated and untreated control chicks which were subsequently challenged orally with pathogenic bacteria, such as E coli or C perfringens.

Competitive exclusion is particularly applicable to modern broiler production because the natural process of the chick acquiring a healthy normal gut flora from the mother hen cannot happen. In modern systems, where the hatching egg and chick are separated from the hen, it is then easy for pathogenic bacteria to colonise the chick’s intestine early in their life. Administering Aviguard, as soon as possible after hatch by spray application, can help keep these harmful bacteria out.

Routines and timing

We also know that normal intestinal flora can be disturbed by stress, disease and antibiotic treatment. Sick birds then excrete pathogenic bacteria into the environment. Thorough cleaning and disinfection will never remove all bacteria from a broiler house, so it is easy for pathogens to remain present in empty houses which can then affect the following crop.

While it is desirable to populate the chick’s intestine as soon as possible after hatch with “good” bacteria, many broiler flocks require treatment with antibiotics under veterinary supervision for the first three days of life to combat E coli challenge. Therefore, timing is crucial in establishing a successful Aviguard programme.

If antibiotics have been introduced to chicks on arrival in the house, a full 48-hour interval is required to allow the chick’s system to become clear of antibiotics before administering Aviguard. It can then be administered in the drinking water using a dosing pump to re-populate the intestine with normal bacteria. The new bacteria take a further 48 hours to establish.

Producer experience

During the past two years we have recorded feedback from a number of broiler units from varying operations and three key feature strongly in responses: Improved litter quality, improved rejection rates and a reduced need for treatment with antibiotics.

We believe that that these performance improvements are partly due to birds with a more natural and complete intestinal flora being better able to cope with the physiological, digestive and environmental stresses likely to trigger enteritis.

Each farm would need to calculate individually the financial benefits that these improvements could mean, but our estimates are that significant uplift in margin is possible.

One of the earliest broiler farms to introduce an Aviguard programme continues to provide regular feedback on health and performance on their farm. There are three sheds housing 30,000 birds and before the programme was established, flocks required regular treatment for enteric challenge starting around 23 days of age, sometimes requiring two complete courses of antibiotics. When Aviguard was introduced, antibiotic treatment reduced over the first few crops and no antibiotic treatment has been needed for the most recent 19 consecutive crops.

With Crop 30, Aviguard was administered in two out of the three houses, and subsequently there was an improvement in litter quality and although there was still some enteritis, its onset was delayed.

However, the magnitude and type of response will vary between units depending on their own bacterial flora, disease history, management, and maybe even the antibiotics used.

In most cases, the programme has been implemented to help proactively manage a continual enteric disease issue but in contrast we have also established programmes where producers are investing in it as a form of insurance against enteric disease and the need for antibiotics.

Dr Sarah Rennie is the integrated livestock marketing manager at Intervet Schering-Plough Animal Health.