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Systematic Review-meta-analysis and Meta-Regression on the Effect of Selected Competitive Exclusion Products on Salmonella Prevalence and Concentration in Broiler Chickens

29 July 2013

Reviewing the published data on the efficacy of competitive exclusion (CE) products, researchers based in Canada found that undefined CE products out-performed most commercial products. Administration of the products by spray in the hatchery was as effective as oral gavage and more practical for farmers.

The effectiveness of various competitive exclusion (CE) products for reducing Salmonella colonisation in broiler chickens was evaluated using systematic review-meta-analysis-meta-regression (SR-MA-MR) by Ashley K. Kerr of Public Health Agency of Canada and co-authors there and at Public Health Agency of Canada, Saskatchewan Ministry of Agriculture, University of Guelph and Mississippi State University.

In a paper in Preventative Veterinary Medicine, the authors explain that relevance screening identified 201 relevant studies that were subjected to methodological assessment. Of these studies, 159 were suitable for data extraction, 66 were presented in a number of MAs and 130 were examined in a meta-regression (MR). Fourteen different CE products were identified, nine of them commercial products, and the most common route of administration was oral gavage (63.7 per cent of trials).

Meta-analyses indicated that a number of CE products reduce Salmonella colonisation in broilers, the most effective one being Preempt™ which was formerly known as CF-3. Five study characteristics (publication year, CE type, CE route, sample origin and Salmonella serovar administered/recovered) and three methodological soundness characteristics (treatment assignment, intervention and laboratory methods description) were retained as statistically significant (p<0.05) in the final MR model.

The MR analysis indicated that, undefined CE products outperformed all commercial products, except for Preempt™ and Broilact®. Both were considered comparable to the undefined chicken source CE culture products in effectiveness.

The administration of CE through spraying the chicks at the hatchery was determined to be just as effective as the oral gavage treatment and more practical for farmers to administer.

Kerr and co-authors say their results could be useful in decision-making concerning the on-farm use of CE products in broiler chickens, and as inputs for risk assessments as the industry pushes for more antibiotic-free alternatives.

Out of the various interventions to reduce Salmonella colonisation in broilers on-farm, CE was the most studied; its inability to be licensed in certain countries and proof of consistent efficacy remains a barrier, they add.


Kerr A.K., A.M. Farrar, L.A. Waddell, W. Wilkins, B.J. Wilhelm, O. Bucher, R.W. Wills, R.H. Bailey, C. Varga, S.A. McEwen and A. Raji?. 2013. A systematic review-meta-analysis and meta-regression on the effect of selected competitive exclusion products on Salmonella spp. prevalence and concentration in broiler chickens. Preventive Veterinary Medicine, 111(1–2): 112–125.

Further Reading

You can view the full report (fee payable) by clicking here.

July 2013



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