NOAH Antibiotics Conference December 1st 1997

Digestive Enhancers.
Paul McMullin
British Poultry Veterinary Association

Many antibiotics have been derived from natural bacterial populations. The natural bacterial population of the intestines of farm animals is extremely complex and variable among species,ages and types of animal. The use of low doses of a wide range of anti-bacterial compounds has been shown to significantly enhance digestion of nutrients in a range of species. The size of this effect varies with species and many other factors. That these compounds are exerting their effect by modulating the bacterial population is confirmed by the fact that they have no such effect when given by non-oral routes or in animals which are germ-free. To people unfamiliar with agricultural production systems this may seem a trivial use for anti-bacterials. The effects of such use are, however, far from trivial. They can have a significant benefit foranimal welfare. Sometimes they act directly by helping control a specific disease such as necrotic enteritis in poultry, but they may also improve welfare by improving the utilisation ofnutrients and reducing the volume or moisture of undigested material deposited in the animals environment. Wider environmental issues are also significant. It is currently estimated that the use of digestive enhancers in pigs and broiler chickens in the UK saves 290500 tonnes of feed,11620 lorry journeys, 714000 cubic metres of water and avoids the need for 25538 hectares of arable land planted with cereals. In addition 532000 cubic metres of pig slurry do not need to be spread. These savings are made every year we continue to use these products.There are also benefits for society and the consumer through the maintenance of animal agriculture and food processing in the UK, both of which provide employment and revenue.Under the current, more liberal, international trade agreements it is inevitable that unilateral bans on these production aids will result in production moving to other countries. Some such countries will not have the same standards of animal welfare as the UK.. The consumer benefits from affordable high quality food. It must also be kept in mind that the profitability ofanimal agriculture is a pre-requisite for the implementation of measures to prevent and/or eliminate infection of food animals with zoonotic organisms. Uniformity of production improves the predictability of harvest and hence the efficiency of cleaning and disinfection inall-in/all-out production systems. The characteristics required of a digestion-enhancing antimicrobial have been well documented and incorporated in the exhaustive product approval processes which has been in place for many years. It is important that both politicians and consumers recognise that zero-risk is a mirage. Non-science-based interference in product approval processes will discourage development and licensing of products, and is also likely to lead to trade disputes. We may conclude that digestive enhancers exert their effect by moderating intestinal flora, thus allowing productivity closer to genetic potential. Their use provides benefit to producers and consumers, but also improves animal welfare, and generally reduces variability in the production system. Elimination of the use of these products will tend to increase the use of therapeutic antimicrobials. Animal production is likely to decline in countries which implement a unilateral ban on these products, to the benefit of those which do not.

The full proceedings of this meeting have been published by the National Office of Animal Health Ltd, Gladbeck Way, Enfield, Middlsex.