Six hundred and twelve “Ross” day old chicks were placed in 36 pens (17 birds in each) and every 4 pen (2 for males and 2 for females) were allocated for one group (9 groups all together). One of these groups considered as the control and did not received any antibiotic up to the end of the experiment, and 8 other groups were allocated to antibiotics consistiong:
Sulfadiazine + trimethoprime (Sultrim). Tylosin tartrate, Salinomycin, Lincomycin + Spectinomycin (Lincospectin), Enrofloxacin, Chloramphenicol, Chlortetracycline and Furazolidone. All groups were vaccinated at 8, 15 and 31 days of ege against Newcastle disease. The above mentioned antibiotics were given to the treatment groups at the 16-20 and 32-36 days of age, but Salinomycin was used in the feed from 16 days of age up to 3 day before slaughtering . Before and after the usagae of drugs, (ie, at 14, 20, 30 and 37 days of age), and also 2 day before slaughtering (at 50 days of age). blood samples were collected and antibody titers against ND Waccine vere measured by Haemagglutination inhibition test (HI). The results were compared by ANOVA and TUKEY test. It was revealed that none of the different antibiotics had any adverse effects on humoral antiboides, and the difference between the mean antibody titer of other groups and control, and males and females were not significant (P > 0.05). The mean antibody titer of salinomycin group at5O days of age was significanly higher than control (P < 0.05).
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