Removal of antibiotic growth promoters from poultry diets: implications and strategies to minimise subsequent problems

Studies with germ-free chicks and antimicrobial compounds have indicated th e significance of the interaction between host nutrition and the intestinal microflora, This interaction has suddenly leapt to prominence as a result of the decision of the European Union to remove several antibacterial agent s from use in animal feed. A consequence of this decision has been a loosen ing of some of the constraints on intestinal bacterial growth rates which w ill benefit from the use of slowly digested ingredients, because undigested feed is a potential substrate for bacterial fermentation. The use of poorl y digestible ingredients runs the risk not only of poor performance, which has always been the case, but now there is an additional danger from bacter ial overgrowth and subsequent disease/intestinal disorders. Variations in t he nutritional quality of the ingredients are therefore of increased releva nce, and any measures that reduce such variations are likely to be of benef it. As a result, the use of enzymes, which are known to reduce variations i n the performance of birds fed on barley-, wheat- and maize-based diets, wi ll need to be revisited, particularly with reference to correct dosage. In the past the use of antibiotics effectively reduced the need to consider en zyme use and dose. Coccidiosis control is also of great interest because of its association with necrotic enteritis. Prevention of coccidiosis and lim itation of the damage to the intestines associated with this disease is of paramount importance if necrotic enteritis is subsequently to be avoided. A s a result, the use of coccidiostats for direct control and betaine and oth er pronutrients for amelioration of the symptoms is receiving greater atten tion. Ultimately it is hoped that nutritional control will lead to microbio logical control, allowing for more consistent production responses in the a bsence of antibiotics.