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Diagnosing dysbiosis in broilers

In October, 2015, IHSIG held the 3rd symposium ‘One World, One Health’ in Ghent, Belgium. Different scientists presented their vision on the latest developments in poultry health.

Keynote speaker at the symposium was professor Filip Van Immerseel. He holds the position of professor in the Department of Pathology, Bacteriology and Avian Diseases, and the Faculty of Veterinary Medicine at Ghent University in Belgium and heads a research group that studies host-bacterium interactions. He gave a joint lecture with Dr Gwen Falony, who is working at the Raes Lab (KULeuven), where he is currently working as a staff scientist on the Flemish Gut Flora Project. An important conclusion from the joint lecture of both scientists is that the intestinal flora of humans and animals are very similar. Van Immerseel: “Actually more than previously thought. This means that human and veterinary research and medicine institutes can learn a lot from each other.” They noticed that, in many gut disorders, bacteria in the family Enterobacteriaceae and a lack of butyrate-producing Ruminococcaceae and Lachnospiraceae are found. The group of UGent is currently conducting a project on the identification of markers to diagnose intestinal health problems, funded by the Institute of Science and Technology, Flanders. In this project, they are looking for microbial markers and host markers that can be detected in blood or faeces. This would enable veterinarians to treat dysbiosis based on a solid diagnosis.

Developing Campylobacter antibodies

Professor Tom Humphrey of Swansea University in Wales gave a presentation entitled ‘Campylobacter: important human and chicken pathogens’. According to Humphrey, Campylobacter is currently the most significant pathogen that can be transmitted from animals to humans through meat. In that framework, more attention should be given to Campylobacter than to Salmonella at present. Currently around the world, Campylobacter is causing a massive number of infections and inflammations. One big problem in the fight against Campylobacter at this time is that there are no concrete measures that can be taken to prevent meat from being contami-nated. The only advice that can be given to consumers is that they should thoroughly roast or cook chicken meat.

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Controlling Campylobacter in ground poultry products
Poultry products are a major avenue for the introduction of Campylobacter into the food supply, with undercooked poultry and cross-contamination as the common way that Campylobacter is transmitted to humans. The largest number of these foodborne bacterial infections is caused by the species Campylobacter jejuni.

According to Van Immerseel, the group of professor Pasmans at Ghent University is currently working on research that involves developing Campylobacter antibodies to be used as feed additives. The antibodies attach themselves to the Campylobacter bacterium, thus impeding the bacterium in its interaction with the chicken gut. These antibodies can then be added to compound feeding stuffs. “They expect to be able to say within months whether it’s going to work or not,” said Van Immerseel. According to the professor, the poultry sector worldwide has Salmonella increasingly under control. “Laying hens are vaccinated and, in respect of broilers, the focus is on good hygiene and decontamination measures.”

[Photos: Phileo, Lesaffre Animal Care]

Clostridium perfringens can survive disinfectants

Professor Richard Ducatelle focused on Clostridium perfringens: 1 pathogen, many diseases, 1 mechanism. Ducatelle is a veterinarian specialised in cell and gene biotechnology and has been head of the laboratory of veterinary pathology at Ghent University since 1993.

He explained that Clostridium perfringens occurs in all intestines of humans and animals. “Traces of Clostridium perfringens can also survive for years in a poultry house and the environment. These bacteria are so strong that they can survive disinfectants.” In principle, Clostridium perfringens is a natural bacterium that is not dangerous under normal circumstances. This is partly because animals create antibodies against this bacterium that bind themselves to the toxins that Clostridium perfringens produces. “And the stomachs of both humans and animals produce acids that make sure that not many soluble proteins that allow this bacterium to proliferate make it to the small intestine.” Under certain circumstances, however, the bacterium can become dangerous. It fumbles the epithelial cells and the tissue in the intestinal wall and can proliferate to enormous levels. Ducatelle: “If it multiplies, de bacterium produces toxic substances sufficient enough to affect the intestinal wall of the chicken. This creates necrotic enteritis, which can be fatal for the animal.”

Solution without use of antibiotics

Clostridium perfringens can destroy the intestinal wall of the small intestine. Ducatelle: “This is where the bacteria multiplies rapidly because it has a large quantity of easily soluble proteins at its disposal.” Clostridium perfringens plays a role in the laying hen sector to some extent, but the problem is huge in the broiler sector. That’s because broilers eat plenty of high protein foods in a short time span. On a worldwide scale, Clostridium perfringens is often kept under control with antibiotics. According to the professor, however, this is unnecessary. “There are many measures that can be taken that enable a reduction in the use of antibiotics.”
“Feed additives with acids can help the acid content in the intestines. As a result, proteins are immediately stored in the stomach, which makes them no-risk.” As regards the type of acids, virtually all types of acids help to acidify the stomach.

In broilers, Ducatelle recommends lowering the protein content in the ration (somewhat). An example of a product that is very high in protein is fishmeal. When a broiler gets too much, the amount of protein no longer stays in proportion to the ability of the stomach to produce acids. As a result, problems arise. Ducatelle: “Antibiotics are, in any case, not the solution. For example, you can choose temporary fasting. We had broilers with necrotic enteritis under laboratory conditions fasting for 24 hours and the problem with Clostridium perfringens went away.”

Low density broiler houses is better

Another cause that leads to Clostridium perfringens is a high occupancy rate in broiler houses. Ducatelle: “We found that the more animals there are per square metre, the greater the risk of necrotic enteritis.” A reduction in the number of animals per square metre also lowers the risk of an outbreak of this bacterium. “As a result, we have fewer problems with necrotic enteritis in Europe than in, for example, South America, the US and Asia.” Another management measure that can prevent Clostridium perfringens is an intensive fight against coccidiosis. According to the professor: “Coccidiosis increases risk of Clostridium perfringens considerably. So it is very important to combat coccidiosis in the broiler sector.”

Dick van Doorn

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