The antimycoplasmal drug tiamulin was administered to groups of native broiler chickens by therapeutic dose, then above, for three successive days in drinking water. The chickens were vaccinated with infectious bursal disease (IBD) and with Newcastle disease (ND) vaccines.
Total protein, electrophoresis fractionation of serum proteins and Histopathological investigation were achieved directly after four days of tiamulin treatment and after a week from last dose. The specific antibody titers against IBD and ND vaccines were determined only at the 2nd period. Results indicated that, in most cases, the therapeutic doses (556 mg. tiamulin / liter) causes hyper-protienemia, hyper-albuminemia and hyper (alpha, beta and gamma) globulinemia at both periods than control. While, in most cases, which received the higher dose level (2224 mg. /L.), causes significant decrease of the above parameters at both periods than controls. The bursa fabricius revealed a slight inflammatory cell infiltration (at 1st period by 1112 mg/L.) and hemorrhages in chickens dosed by the higher dose (at the 2nd period) than in vaccinated non-treated ones.
Microscopically, the thymus showed slight hemorrhages by the higher by the higher dose at the second period. There were no significant variations of the specific antibody titers between tiamulin treated chickens and vaccinated control ones against both IBD and ND vaccines. Based on this results, it could be concluded that tiamulin (by all doses) is not an immunosuppressive for IBD and ND vaccines, but in contrast, the therapeutic dose level showed a slight immuno-stimulant due to induction of a hyper gamma globulinemia in the 2nd period.