Contribution of exogenous enzymes to potentiate the removal of antibiotic growth promoters in poultry production

Removal of prophylactic in-feed antibiotics from the diets of animals that enter the human food chain is increasing on a global basis. This removal is motivated by a range of factors including legislative compliance, consumer and retailer pressure and for ethical reasons. However, whilst this shift in approach to the rearing of production animals has benefits, there are also significant challenges for animal husbandry, disease control, nutritional optimization and food safety and security. For example, the use of in-feed antibiotics generates increases in weight gain and feed conversion ratio in the region of 4% and so, axiomatically, their removal introduces significant efficiency cost for producers. The vacuum created by the removal of in-feed antibiotics has led to a sustained body of research into alternative additives such as plant secondary metabolites, pro and pre-biotics, acidifiers and enzymes. Whilst no single alternative to date can claim to demonstrably and consistently replace the antibiotics, many of these additives have substantial value and can form part of successful 'anti-biotic free production programs. It is therefore the purpose of this review article to summarise the consequences of removal of in-feed antibiotics and to highlight the potential of feed enzymes as part of a displacement strategy.