EFFICACY OF TYLOSIN TARTRATE ON MYCOPLASMA INFECTIONS AND EGGSHELL APEX ABNORMALITIES IN LAYER HENS UNDER FIELD CONDITIONS

The aim of this report was to describe a clinical c ase of concurrent infection with Mycoplasma Gallisepticum (MG) and Mycoplasma Synoviae (MS) in layers, complicated with Escherichia coli and Pasteurella multocida , as well as to evaluate the efficacy of tylosin ta rtrate treatment (Pharmasin ® 100% WSG, Huvepharma) on Mycoplasma under field conditions. A flock of 18,500 ISA Brow n pullets, 21 weeks of age and MS positive, showed an increase in weekly mortality, with no influence on egg production. At 24 weeks of age, post mortem was carried out and blood samples were collected, as well as samples for microbiological cultures from the lesio ns. In necropsy, several findings of pericarditis, airsacculitis of posterior thoracic sacs, prolapse and egg yolk peritonitis were found. Sporadic neuro logical signs were also apparent and post mortem examination revealed yellow caseous exudate accumulations in cranial bones. Although egg production was not infl uenced, Eggshell Apex Abnormalities (EAA) were increased with a significant number of both broken and misshapen eggs together with discoloration. Eli sa serological examinations for Infectious Bronchitis Virus (IBV) and Newcastle Disease Virus (NDV) were within vaccination program limits, but MS, MG and Avian Rhinotracheitis (ART) results showed a significant seroconversion. Microbiology also revea led the presence of Escherichia coli and Pasteurella multocida . On week 25, a drug treatment with tylosin tartrat e was applied at a dose of 105 mg kg -1 body weight in drinking water for five consecutive days. Three days after treatment, misshapen, broken and discolored eggs were decreased. The mortality was also significantly decreased within a week since the beginning of tylosin administration and at 30 weeks of age was within acceptable levels. Post mortem evaluation confirmed the absence of previously gros s lesions in primary organs. In summary, tylosin tr eatment in complicated Mycoplasma spp. infections under field conditions improved eg g shell quality and decreased mortality, thus the economic losses linked to decre ased egg production and labor costs were reduced.