Effect of low level feeding of tylosin and zinc bacitracin on the weight gain and immunity of broiler chicks vaccinated against newcastle disease virus

The study was aimed to reveal the effect of low level feeding of Tylosin (tylan premix) and Zinc bacitracin (Albac) on the weight gain and immune response of broiler chicks vaccinated against Newcastle disease virus. Two hundred and forty day-old chicks were purchased from local market. They were divided into 3-group i.e. A, B and C, each group was further divided into 2 sub- groups i.e. A1, A2, B1, B2, C1 and C2. Group A was fed Tylosin (Tylan premix) at the dose rate of 20gm/50kg of feed, 10-42 days of age. Group B was fed Zinc bacitracin (Albac) at dose rate 12gm/50gm of feed, 1-42 days of age. Group C was fed on un-medicated feed A1, B1 and C1 were vaccinated at 7 and 21 days against NDV and A2, B2 and C2 were reared without vaccination. The parameters studied were (1) the effect of low level feeding of Tylosin and Zinc bacitracin in broiler chicks on weight gain, (2) feed conversion ratio and HI titre of Newcastle disease virus vaccinatio n was monitored on weekly basis up to 42nd day of age. This study indicated that Tylosin and Zinc bacitracin when used at recommended dosage levels (20gm/ 50kg feed and 12gm/50kg feed respectively) did not interfere with the development of birds, immune response of birds in vaccinated groups. Their medication in feed rather produced beneficial effects on weight gain and antibody production due to heavier weight and good health status. Their weight gain studies indicated that the medicated and vaccinated birds fed on Tylosin and Zinc bacitracin medicated feeds had significantly higher body weights than those fed on non-medicated and non- vaccinated group at 42 days of age. The immune response of vaccinated birds was higher than those of non-vaccinated birds in the presence of medication. However, there was a need for further investigation.