Abstract

Chronic respiratory disease (CRD) is one of the most important veterinary diseases in Iran and all over the world. Mortality, reducing of weight gain and increasing of feed conversion ratio (FCR) are caused by CRD. Several drugs are used for prevention and control of CRD. CRD is caused by Mycoplasma gallisepticum (MG). Tiamulin and pulmotil are effective on M. gallisepticum. By considering generating resistance against antibiotics that is effective on MG, studying the effect of these drugs in the treatment and prevention of CRD in birds were the purpose of this research. In this study, tow broiler  flock (MG positive) and layer flock (MG free) with 15000 birds, divided  in  six similar  groups (A, B, C (layer), D, E and F (broiler))  with  2500 bird in  each  group. 13 and 100 g tiamulin in 200 L of water was used in Groups A and D, respectively. 60 ml pulmotil in 200 L of water was used in Groups B and E at the same time. However, the birds in Groups C and F (control groups) did not get any antibiotic. Gross lesions and mortality of CRD, minimum inhibitory concentration (MIC) of tiamulin, pulmotil and other common antibiotic dicks, hen-day percentage in layers and growth parameters in broilers of control and experimental groups were calculated. The basis of ANOVA analysis was that the use of antibiotics such as tiamulin and pulmotil significantly reduced mortality and gross lesions (P < 0.05). Also, it improved hen-day percentage in layers and growth parameters in broilers (P < 0.05). It can be concluded that usage of these antibiotics can be essential in the treatment and prevention of CRD in birds.

Key words: Pulmotil, tiamulin, chronic respiratory disease (CRD), birds, minimum inhibitory concentration (MIC).