Field Evaluation of a Live Avian Metapneumovirus Vaccine in Broiler Farm

Avian Metapneumovirus (AMPV) belonged to Paramixoviridae family has potential to produce acute contagious upper respiratory tract infections in fowl and turkey. Strategy of vaccination is one of the most important ways to control of AMPV disease. The objective of this study was evaluation of efficacy of a commercial live AMPV vaccine in a broiler farm. Vaccine was administrated by ocular rout at 14 days old of age in one broiler farm with a history of AMPV contamination. Zootechnical performance was evaluated and recorded until the end of rearing period (42 days of age) for test and negative control groups. Also in the days of 1, 14, 28 and 42, antibodies titers against AMPV and IBV were measured by ELISA and against ND and AI by HI methods. Statistical analyses by Mann-Whitney method showed that no significant differences (P>0.05) between two groups in zootechnical performance (mortality, body weight, FCR and EEF). Although these parameters were better in test group numerically. Also, no significant differences were found in antibody titers and CV against AMPV, ND, IBV and AI statistically (P>0.05) too. Vaccination against AMPV induces low humeral antibodies and so, serological tests can not prove the vaccine efficacy. It should be considered that CMI immunity play a great roll in protection against AMPV and seronegative birds are not lack of immunity against AMPV.