Necrotic enteritis (NE) caused by Clostridium spp. is an economically significant bacterial disease of poultry worldwide. Traditionally the disease has been prevented through feed supplementation with antibiotics sub-therapeutically as antimicrobial growth promoters (AGPs). However this practice has led to the emergence of resistant pathogenic microbes and drug residues, potentially threatening animal and public health. Therefore the marketing and incorporation of AGPs into poultry feed has been banned in Europe which has exacerbated the incidence of NE, bringing about huge economic losses to poultry farmers. Poultry researchers, exporters and consumers have emphasised AGP-free poultry rearing and have been searching for non-antibiotic and cost effective alternatives to control NE. Strategies suggested include vaccination, coccidiosis control, probiotics, competitive exclusion products, prebiotics, egg yolk immunoglobulins, bacteriophages (or phage gene products), organic acids, feed enzymes, plants and plants extracts/essential oils and nutritional changes.
There are many predisposing as well as virulence factors for NE induction and pathogenesis and more are expected to be discovered in the future. The ambiguous pathogenesis trend of the disease is still hindering the development of a potent active vaccine against NE. The choice of a single and fully effective approach is difficult. However, probiotics and specific egg yolk immunoglobulins (IgYs) alone or in combination could serve as promising strategies for controlling NE in broilers in the absence of AGPs.