Maternal antibody transfer in free-living and captive mallards

From April until June 2010, free-living female mallards were caught from their nest in a woodland area in the Alblasserwaard, the Netherlands. Each captured female was marked with a metal ring, aged and several measurements were collected (tarsus length, head+bill length, wing length, body mass). Blood samples were collected for detection of antibodies to avian influenza virus (AIV). Per clutch two eggs were collected, of which the length and breadth was measured to assess egg volume. Egg yolks were separated to assess maternal antibodies to AIV, embryo size was measured and sex of embryos determined. In the same period, blood samples and several measurements (tarsus length, head+bill length, body mass) were collected from captured females in an outdoor aviary in Heteren, the Netherlands. Four eggs per clutch were collected (one per egg stage), of which the length and breadth was measured. Egg laying order was assessed. Egg yolks were separated and embryo size was measured. Serial dilution was applied to validate the use of OD-values of egg yolk and female serum as a quantitative estimate of antibody concentration