Other Antibiotic Growth Promoters

More recently, a range of other quality and safety issues have been recognised by consumers and now influence poultry meat and egg buying patterns and behaviour. Most importantly this includes (i) the routine use of antibiotics as growth promoters and curative medicines and the potential for development of transferable antibiotic resistance, (ii) risk associated with enteric pathogen (e.g. Salmonella and Campylobacter) and toxin (e.g. dioxin) contaminants of poultry products, (iii) the environmental impact of poultry production and (iv) the sensory and nutritional quality of eggs and poultry meat (Menzi et al., 1997 Hamm et al., 2002 Rodenburg et al., 2004 Horsted et al., 2005). 

In Europe about 10,000 tons of antibiotics are consumed each year (FEDESA, the European Animal Health Association 1998) [59] (see Table 2). According to these data, 5,000 tons are due to veterinary purposes (3,500 tons prophylaxis and therapy, and growth promotion about 1,500 tons). The other half of production is used in medicine. Among the antibiotics used in veterinary practice,... 

Lasalocids, SaUnomycin, Narasin guard against coccocidiosis. These ionophores are also used in cattle and swine as growth promoters. They generally have a different mode of action compared to other antibiotics. 

Lincomydn is an antibiotic produced by Streptomyces lincolnensis. It is used in monopreparations or in combination with other antibiotics such as spectinomycin, sulfamethazine, and gentamicin, for the initial treatment of mild to moderate staphylococcal infections in a variety of animal species. It can be administered orally to poultry at dosages equivalent to up to 50 mg/kg hw/day for up to 7 days, and to swine at dosages equivalent to up to 10 mg/kg bw/day for up to 21 days. In calves, sheep, goats, and swine, it can be administered intramuscularly at dosages of up to 15 mg/kg bw/day for up to 4-7 days. It is also added in feeds for growth-promoting purposes. 

Since many of the above-mentioned compounds possess major anti-infectious activity in addition to their role as growth promoters, the methods of their determination in edible animal products have already been discussed in other sections of this chapter. Hence, this section concentrates on the remaining compounds within this group, namely the organic arsenicals, peptide antibiotics, quinoxaline-1,4-dioxides, and miscellaneous substances. 

While the plea to more closely regulate the clinical use of antibiotics in humans is an obvious admonition to the medical community (humans take an estimated 3 million pounds yearly), there are other sources of concern. For example, the American Medical Association estimates that more than half of the total mass of antibiotics used in the United States is fed to animals, not to cure them of illness, but as growth promoters or to prevent illness. The Animal Health Institute, which represents makers of animal drugs, indicates that more than 20 million pounds of antibiotics are used yearly in the United States. The Union of Concerned Scientists estimates that as little as 2 million pounds go to sick animals. This is exactly the type of profligate usage that promotes the emergence of resistance. 

Animals and humans constitute overlapping reservoirs of resistance, and consequently the use of antimicrobials in animals can have an impact on public health. For example, the occurrence of vancomycin-resistant enterococci in food-animals is associated with the use of avoparcin, a glyco-peptide antibiotic used as a feed additive for the growth promotion of animals. Vancomycin resistant enterococci and vancomycin resistance determinants can therefore spread from animals to humans. The bans on avoparcin and other antibiotics as growth promoters in the EU have provided scientists with a unique opportunity to investigate the effects of the withdrawal of a major antimicrobial with respect to the selective pressure on the occurrence and spread of antimicrobial resistance. Data shows that although the levels of resistance in animals and food, and consequently in humans, were markedly reduced after the termination of use, the effects on animal health and productivity were very minor. ° ... 

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