Objective: To evaluate the rate and half life of maternal antibodies against Al in broiler and layer chicks.
Design: Prospective longitudinal study.
Animals: 400 broiler and layer chicks (0-2 1 days).
Procedure: Sampls from chicks in days 0,7,14,and 21. Determination of were taken and antibodies titre were determined by Hemagglutination Inhibition (HI) test using H9N2 strain of Al virus and estimation of half life of the antibodies.
Statistical analysis: Analyzis of variance, Duncan’s multyibe sange test.
Results: Mean HI titres (log 2) at different sampling intervals in the three groups were: I) Broiler flock from hens challenged with virus:
4.2, 2.7, 1.5, 0.4, half life of maternal antibodies: 5.5 days. 2) Broiler flock from hens vaccinated against the disease: 7.1, 5.4, 4.1, 2.3, half life of maternal antibodies: 4.5 days. 3) Layer flock: 4, 3.2, 2.7, 2.1 half life of maternal antibodies: 11 days. The half of antibodies in layer flock were significantly longer than broiler flocks and the difference between broiler groups were not statistically significant.
Clinical implications: The results indicate that , the suitible time for vaccination of chickens with maternal antibodies in the broiler flocks is at 7 to 14 days of age (depending on their primary Ab titres), and at 14 to 21 days of age for the layer flocks. J. Fac. Vet. Med Univ. Tehran. 57, 1: 47-50, 2002.