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Abstract
Studies on the effects of antibiotics on immune response of vaccinated chickens against Newcastle and Avian Influenza vaccines
The effects of antibiotics (spiramycin, tylosin and cefotan) on immune response of vaccinated chickens against Newcastle and avian Influenza was studied. One hundred and fifty chicks were used and divided into 5 groups each group contain 30 chicks.
The description of treatment and vaccination of 4 groups are presented in Table (1) while the fifth group was kept as non- treated, non-vaccinated control one. Techniques used for evaluation of humeral immune response of chicks post vaccination included the H.I. and phagocytic activity for cellular immune response. Our obtained results revealed that:
At 7 days old a significant increase in ratio of bursa to body weight ratio (B/B) was reported in spiramycin group (G1). However, there was non-significant effect in spiramycin (G1), tylosin (G2) and cefotan (G3) groups compared to non-treated vaccinated group (G4). However, it was observed there was non-significant effect of antibiotics on thymus weight among G1, G2, G3 and G4. Our results results indicated that non- significant effect of antibiotics on spleen to body weight (S/B) ratio along the period (40days ) except at 7 days old spiramycin group cause significant increase in S/B ratio. However, at 19 days old cefotan group (G5) cause a significant decrease in S/B ratio.
The effect of antibiotics on the immune response to ND vaccine no significant effect for antibiotics at 7 and at 12 days old. At 19th and 26th day spiramycin, tylosin groups indicated that a significant decrease in H.I.titer of Newcastle vaccine compared to non- treated vaccinated group (G4) while no effect for cefotan on H.I. titer was reported. At 33days old, all antibiotics had no significant effect on immune response. At 40 days old, all antibiotics resulted a significant increase immune response to ND vaccine compared to non- treated vaccinated.
Regarding the effect of antibiotics on the immune response to AI vaccines, results revealed that at 7 days old, all antibiotics groups caused a significant decrease in H.I. titres than obtained from non- treated vaccinated group. It was observed that cefotan group (G3) at day 12th caused significant decrease in the H.I. titer of AI vaccine compared to non- treated vaccinated group (G4). At 19 days old, no significant effect for antibiotics treated groups on AI antibodies titre was reported. At 26 days old, after 16 days post AI vaccine H.I. titer of antibiotics were significant higher than non- treated vaccinated group. It was observed that at 33 days old, the tylosin group (G2) has a significant increase in titer compared to non-treated vaccinated group. At 40 days old, (4 weeks post vaccination) titer of antibodies of cefotan group (G3) and spiramycin (G1) were significantly lower than those found in tylosin (G2) and non- treated vaccinated group (G4).
Antibiotics had no significant effect in phagocytic activity except except at 26 days old, spiramycin (G1)and tylosin (G2)treated group caused a significant increase compared to non-treated vaccinated group (G4).
Regarding effect of antibiotics on phagocytic index, non significant effect for antibiotics on phagocytic index except at 19 and 26 days old, cefotan (G3) resulted in a significant increase compared to non- treated vaccinated group(G4).