Immune status of commercial layer birds against Ranikhet disease was studied in twelve commercial layer farms with similar managemental practices in and around Thalaivasal area of Tamil Nadu. All the birds were vaccinated against Ranikhet disease at 1,4,12 and 19 weeks of age. They were screened for antibody titer against Ranikhet disease on 40 th week and were compared with the production performance of layers from 35 th to 40 th weeks of age. The result revealed that 7 commercial flocks showed the Haemagglutination Inhibition (HI) titer of above 2 8 with no variation in the production performance (88 to 90 percent). Whereas the remaining flocks recorded a HI titer of less than 2 5 indicating their susceptibility to Ranikhet disease with fluctuation in the production performance (80 - 90 percent). Hence it is inferred that low-level antibody titer against Ranikhet disease also influence the production performance of commercial layers.

Source : IPSACON-2005

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