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Abstract
There can be no doubt that antibiotics have proved of immeasurable benefit to both man and domesticated animals during the last 40 years. Antibiotics are widely used in poultry farms not only for treatment and control of infectious diseases but also as feed additives for growth promotion. This practice, however, carries many disadvantages, such as the stimulation of microbial resistance to antibiotics, with the possible transfer of resistant pathogens from animal to human. The extensive use of these drugs in laying hens leads to appearance of the problem of drug residues as a result of excretion of such drugs in the eggs during and after treatment. Residues in eggs pose human food safety concerns and may adversely affect consumer confidence in this poultry product.
The present study was conducted to determine the use of veterinary drugs in poultry production, to determine the antimicrobial drug residues in laying chickens, and in commercial eggs, and determine the effect of cooking and that of storage period on the amount of antimicrobial residues in eggs.
The following was adopted to fulfill this aim:
1. Description and evaluation of the safe and hygienic egg production.
A questionnaire was used to collect data describing and evaluating the hygienic egg production in 10 commercial egg producing farms through interviewing the owners of the farms in Alexandria. The questionnaire covered the sanitary aspects of farms design, the safe procedures used for disease treatment and control as well as for egg handling, describing brooding, growing and production period of layers, type and composition of ration, the produced eggs, diseases affecting flocks, vaccination programs, lighting programs and procedures for disinfection.
2. Testing the presence of antimicrobial drug residues in laying hens and in produced eggs in two poultry farms by using microbiological agar diffusion method.
A total of 100 laying hens were randomly selected from two poultry farms in Alexandria (50 hens from each farm). A total of 100 chicken feaces samples as well as 100 commercial egg samples were collected from the selected hens and tested for the presence of antimicrobial drug residues.
3. Testing the presence of antimicrobial drug residues in laying hens experimentally treated with Amoxicillin and in produced eggs.
3.1 A total of 50 laying hens were selected during drug administration. Terminal feaces were collected from each hen and tested for the presence of antimicrobial drug residues.
3.2 A total of 215 commercial egg samples were randomly selected from the previously mentioned Amoxicillin treated farm for antimicrobial drug residues determination. These samples were divided as follows:
3.2.1. A total of 50 commercial eggs were randomly selected from the farm during Amoxicillin administration for detection of antimicrobial drug residues in raw eggs during drug administration.
3.2.2. A total of 70 commercial eggs were randomly selected from the farm during the withdrawal period. These were collected as 10 egg samples which were taken from the farm daily after the end of drug administration for 7 successive days for detection of antimicrobial drug residues in raw eggs.
3.2.3. A total of 80 commercial eggs were randomly selected from the farm during drug administration. These included 40 egg samples which were stored for one month at room temperature and 40 egg samples which were stored at the refrigerator. Ten egg samples were examined at each of 7th, 14th, 21st and 28th days for the presence of antimicrobial drug residues.
3.2.4. A total of 15 commercial eggs were randomly selected from the farm. These were boiled for 10 minutes then examined for antimicrobial drug residues.
4. Testing the presence of antimicrobial drug residues in commercial eggs collected from Alexandria market (2007).
A total of 50 commercial egg samples were randomly collected from Alexandria markets and tested for presence of antimicrobial drug residues.