Antibiotics Use In Medicine & Livestock Feed Production

Antibiotics Use In Medicine & Livestock Feed Production

Antibiotics Use In Medicine & Livestock Feed Production

Introduction

The term 'antibiotics' is now used to describe a broad and diverse range of chemical compounds that destroy, or limit, the growth of microorganisms. Antibiotics may have activity against bacteria, fungi, or protozoa, though not viruses, and are used widely as veterinary drugs in food animals by the farming industry. There are many classes of compound with antibiotic properties, but some of the major groups in use are the ß-lactams (including the penicillins), macrolides, ionophores, quinolones, lincosamides and tetracyclines.

Antibiotics may be administered to food animals for two reasons. They may be used, at relatively high doses, as therapeutic agents to treat clinical infections, or they may be administered at low, sub-therapeutic doses as 'growth promoters'. The use of antibiotic growth promoters in intensive livestock farming has been shown to be an effective means of increasing the growth rate of food animals and improving the quality of meat by raising the protein content. It is not entirely clear how this effect is achieved, but it seems likely that antibiotic growth promoters in animal feed suppress some of the bacteria in the gut and allow more of the energy in the feed to be diverted to the growth of the animal. A further benefit of antibiotic growth promoters is said to be improved control of disease caused by bacterial pathogens, including Salmonella and Campylobacter, in intensively reared livestock(Jones, 1998)(Phillips, 1999).

Analysis

The use of antibiotics in food animals has both direct and indirect implications for food safety. Some antibiotics and their metabolites may be toxic to humans, or may cause serious reactions in sensitive individuals (e.g. penicillins). Therefore antibiotic and antibiotic metabolite residues in meat, milk and other animal products may be a direct risk to human health. However, many experts currently consider that the development of antibiotic resistance in pathogenic bacteria that can cause disease in animals and humans (zoonoses) is a much more serious potential threat to human health, and the use of antibiotic growth promoters is widely thought to have contributed to reported increases in the prevalence of antibiotic resistance.

The farming industry is a significant consumer of antibiotics, and it has been estimated that as much as 60--80% of antibiotics produced in the United States are administered in feed to healthy livestock at non-therapeutic levels. Many of these antibiotics are closely related to compounds that are administered to humans in clinical settings, and include tetracyclines, macrolides, streptogramins, and fluoroquinolones(Bywater, 2000)(Casewell, 2003).

Antibiotic residues are most likely to be found in foods of animal origin, such as meat, poultry, fish, eggs and honey. They are usually present as a result of the use of therapeutic veterinary drugs to control infection and disease in food animals. Antibiotics are frequently used to treat mastitis in cows, and therefore antibiotic residues may be present in milk. Antibiotic residues in milk can pose significant problems to the dairy industry, as many of ...