Effect of Different Factors of Time on the Antimicrobial Agent Resistance

In this study, 318 commercial broiler flocks from 18 Parent Stocks with different breeder age were investigated to assess the changes of antimicrobial agent resistance. All samples were collected from April 2009 to March 2012 and Parent Stocks age was between 30 to 63 week years old. The majority of isolates were resistant to Tylosin and Erythromycin, the minimum resistant to Gentamicin and Ciprofloxacin were found and other antimicrobial susceptible test showed different resistance percentage from 20.75 to 43.40. These data suggested that the time passing as an independent factor whether in the study as seasonal changes or as passing of different years and without effect of other factors cannot be effective on increase of the bacterial resistance and, also, antimicrobial agent resistances found in chickens' showed a significant increase when the age of breeders is increased.