Effects Of Apramycin On Immune Function Of Broilers With Different Dosage

Drug is one of the most important factors which can affect poultry's immunity. Apramycin as the ramification of Aminoglycoside is a new antibiotic for animals which has a great prospect. As is known Streptomycin which also belongs to Aminoglycoside can cause immunosuppression of poultry. The purpose of experiment is to discuss the effect of Apramycin to poultry's immunity.In order to give poultry farmers some advice on how to utilize Apramycin Sulfate effectively, it was used on this trial as a preventive drug to observe its effects on the immune system.In this study, 120 Ross-308 broilers were randomly divided into four groups. As blank control, no drugs were used to chickens in group A. Chickens in group B, group C and group D were respectively watered Apramycin of commendatory dosage(0.045%), three times dosage(0.135%) and five times dosage(0.225%) for five days since the 10th day. The all chickens were immuned with ND-H120 on the 7th day and C30 on the 21st day, and the antibody titers were detected on the 17th day and the 33rd day. At the same time, autopsy were performed on the random ten chickens, index of immune organs were detected and fabricius bursa, spleen and thymus were respectively sliced to observe pathological and architectonic changes.The result showed that (1) HI antibody titers: At the 17th day, no significant differences between group B and group A. The result in group C was lower than group A but with no obvious meaning. There was a significantly lower of 10.71% in group D than in group A. At the 33rd day, the HI antibody titers: group B and C were both lower than group A but with no obvious meaning, and there was a significantly lower of 9.33% in group D than in group A.(2) Index of immune organs: At 17 and 33 days of age, the spleen index decreased with the increase of the Apramycin dosage, but compared to group A, there were no obvious meaning in group B, C and D. No significant differences of the thymus index between group B and group A, but in group C was lower than in group A by 7.04%and 9.66%, and in group D was lower than in group A by 13.43%and 10.60%. the fabricius bursa index: No significant differences between group B and group A at 17 and 33 days of age, but in group C was lower than in group A by 8.8%and 8.25%, and in group D was lower than in group A by 14.88%and 12.81%.(3) The observation of thymus, spleen and fabricius bursa histological section: Barely histology difference was found of spleen in Apramycin with different dosage. No damage of thymus and fabricius bursa in group A were found. Thymic cortex lymphocyte of group B and C were loose and decreased in number, but no damage in medulla was found. Fabricius bursa lymph folliclel lymphocyte of group B and C were loose and necrosis of cortex lymphocyte, but no damage in medulla was found.The result showed that Apramycin of commendatory dosage has no harm to humoral immunity and immune organs of broilers, but heavily dosed Apramycin could lower HI antibody titers and affect the development of thymus and fabricius bursa.