The improvement in the growth of birds through the use of antibiotics could
be obtained by reducing the count of harmful microorganisms, providing beneficial
ones by suitable growth media, decreasing the thickness of gut mucosa and regulating
the motility of gut, leading to better absorption of nutrients. However, achieving these
desirable goals is not devoid of risks. Where, the frequent and improper use of
antibiotics can reverse their therapeutic advantages through giving the opportunity to
any existent microorganism to develop antibiotic resistance, which can hinder the
effectiveness of antibiotics as chemotherapeutic or prophylactic agents in poultry.
Additionally, antibiotic resistance genes can be transmitted to the natural environment
and contaminate soil, water and plants. Moreover, the indiscriminate application of
antibiotics could result in the accumulation of noticeable amounts of drug residues (the
parent compounds or their injurious metabolites) in the edible tissues of poultry,
including eggs and meat, which are very important sources in human feeding. The
residues of antibiotics in poultry products can result in various pathological conditions
and hazardous impacts on human health, such as being sensitive to antimicrobials in
addition to allergy, cell mutations, imbalanced microbiota in the intestine and the
development of bacteria resistance to antibiotics. This chapter describes the benefits
and the hazards of using antibiotics as growth promoters in poultry feeding.
Keywords: Antibiotics, Feed additives, Growth promoters, Poultry.
