6. Conclusions
Whether or not the livestock industry is to blame for the emergence of antibiotic-resistant bacteria, the reality is that the consuming public does not like the idea of routinely feeding antibiotics to animals, for whatever reason, and so North America may follow the European lead, either by government regulation or voluntarily, to reduce or discontinue the use of AGPs in animal feed. Experiences of many European countries yield important information about how we might best cope with a restricted use of anibiotics and what changes we might expect in North America. Experiments from Sweden and Denmark have confirmed that one of the key problems for countries reliant on wheat-based formulations is the control of NE once AGPs have been removed. Currently, many parts of the world are experimenting alternative feed additives that may be used to alleviate the problems associated with the withdrawl of antibiotics from feed. To date no single preventive therapy that can substitute for in-feed antibiotics in poultry feeds has been found. Effective non-antibiotic prevention of C. perfringens-associated health and performance problems will only be attained by means of extensive multidisciplinary research efforts. There are number of alternatives including prebiotics, probiotics, enzymes, essential oils, organic acids and hen egg antibodies that may be used strategically to decrease the incidences of NE in poultry. However, limited data has been presented to support the efficacy of AGPs alternatives. Hence, more research on the use of these products to control NE is required, particularly on the use of prebiotics, essential oils, organic acids and hen egg antibodies. Furthermore, the effect of feed composition, particularly the effect of grain source and amino acid profile on NE requires significantly more study. Improved understanding of the relationship between feed chemistry and C. perfringens populations may aid in the formulation of broiler diets that reduce the incidence of NE in the absence of in-feed antibiotics. Increased feed particle size, the feeding of whole wheat, feeding corn-based diets, reducing non-starch polysaccharides and reducing the level of animal-based proteins in the diet all seem to help reduce the incidence of NE. Management factors other than feeds and feeding (genetics, stocking density, lighting programmes, litter composition, etc.) can also be helpful in the absence of antibiotic growth promoters.