Effect of alternatives to antibiotic growth promoters on broiler performance.

The benefits of supplementing poultry feeds with a mixture of herbal essential oils and plant extracts are well documented (William and Losa, 2002;Hernandez et al., 2004 ;Alcicek et al., 2004).These products are commonly used in poultry feeds due to their antimicrobial effects.The anti-microbial activity of spices and essential oils has been attributed to a number of substituted aromatic molecules, such as eugenol, cinnamaldehyde, and carvacrol (Juven et al., 1994;Bergonzelli et al., 2003).Eugenol has been reported to inhibit the growth of E. coli (Blaszyk and Holley, 1998) while cinnamaldehyde inhibited the growth of E. coli and Salmonella typhimurium (Helander, 1998).A blend of capsicum, cinnamaldehyde and carvacrol has been found to lower the number of E. coli and Clostridium perjringens in caeca (Jamroz and Kamel, 2002).Thus, feed additives with anti-microbial activity have been considered as potential alternatives to antibiotics, as they improve performance of broilers through the control of the microtlora.The major objective of this project was to evaluate the effect, on performance of broiler chickens, of various products as potential alternatives to AGPs.To this end, four broiler trials were conducted in which the efficacy of various feed supplements was compared with a commonly used AGP.Chapter 1 is a review of the literature on the role of antibiotics in broiler production, and presents information on possible alternatives to AGPs, including prebiotic compounds, probiotic organisms, enzymes, organic acids and herbs and essential oils .Chapter 2 evaluates the use of feed supplementation with organic selenium (Selplex) and a prebiotic (Bio-Mos) on the fertility of male broiler breeders, as well as E. coli concentrations in the faeces as an indicator of transferal through cloacal contact during natural mating.In Chapter 3 a comparison is made between AGPs (Zinc bacitracin) and a prebiotic (Bio-