Competitive exclusion in poultry––30 years of research

Abstract The most effective and harmless method available to control intestinal disturbances in poultry is competitive exclusion or CE. The treatment is fully biological, it does not leave any residues and only one treatment on the day-of-hatch is normally enough. The concept was originally designed for Salmonella reduction in growing chickens but has with time been expanded to involve several other enteropathogens like chicken and human pathogenic Escherichia coli , Clostridium perfringens , Listeria and Campylobacter . The chicken intestinal flora has further been shown to be efficacious also in other avian species like turkey, quail and pheasant. Very little is known about the mechanism itself. Protection depends upon the administration of viable anaerobic bacteria and the two most often cited mechanisms are production of volatile fatty acids in the caeca, and occupation of sites on the mucosa. The CE treatment is applied either by spraying in the hatchery or on the farm or via the first drinking water on the farm. The treatment has also been given successfully to older birds after therapeutic doses of antibiotics to regenerate the intestinal microflora. In addition to pathogen control, it has been shown in field studies that CE treatment enhances the growth and decreases the mortality of birds and improves the feed conversion. The nutritional effects of the treatment have been confirmed in well-controlled laboratory studies. Research on CE has proceeded in many countries around the world already for 30 years since the first article in Nature in 1973 by Nurmi and Rantala and several commercial CE products have been developed. Among factors that can affect the efficacy of the CE treatment are antimicrobials, stress and disease, moulting and feed withdrawal and infected breeders and contaminated hatchery area.