The Efficacy of Tilmicosin against Brolier Chickens Infected with Mycoplasma gallisepticum Isolated in Thailand

Abstract

Sixty 1-day-old-female broiler chickens were divided into groups as follows. Thirty birds were randomly selected to be bled from jugular vein for Mycoplasma gallisepticum (MG) antibody assay and swabbed at yolk sac for the detection of MG DNA by using PCR. The remaining birds were divided into three groups, 10 birds per group as follows. Group 1 was a sham negative control. Group 2 received MG serving as a positive control, whereas group 3 received MG and simultaneously treated with tilmicosin incorporated into drinking water. Each bird received MG that was injected into the left thoracic airsac, with 0.1 ml of inoculum containing MG organisms 106 CFU. Each group was raised on a wired cage in 3 isolated rooms with similar environmental conditions. Clinical sign and mortality rate were observed during 1-39 days old. Dead birds were necropsied and swabbed from left thoracic airsac for the detection of MG DNA. At 39 days old, all birds were bled, then necropsied to determine the gross airsac and microscopic tracheal lesion scores and simultaneously swabbed at the left thoracic air sac for the detection of MG DNA. Results revealed that the numbers of birds that showed clinical signs, mean gross airsac and microscopic tracheal lesion scores of group 3 were significantly less than those of group 2 (p<0.05).