Influence of the age of turkey layers on selected serological parameters and the transfer of maternal antibodies to chicks hatched from their eggs

The purpose of this study was to compare the effect of the age of the breeder flock of commercial BUT - 6 turkeys on the transfer of maternal antibodies to chicks. The blood samples for serological analysis were collected from randomly selected 63 female breeders from a flock of BUT Big 6 turkeys and 63 one-day-old hybrid turkey poults hatched from eggs from this flock at 36, 45 and 54 week of age. During blood analysis (serum) in the laboratory, the level of antibodies of the breeder flock against Avian metapneumoviruses (APV), Newcastle disease virus (NDV) and Hemorrhagic enteritis virus (HEV) was determined (ELISA). Maternal antibody (MatAb) titer in chicks (serum) against the same viruses were also determined. The percentage (%) transfer of MatAb to offspring was then evaluated. The effect of the age of the turkeys on the antibody titer to the tested pathogens expressed in geometric mean titers (GMT) was shown. During the laying period, the antibody titer of the tested turkeys against NDV decreased with the age of the flock. The highest antibody titer was demonstrated in week 36 (GMT=14242), whereas the lowest was in week 54 (GMT=5564). In contrast, the serum antibody titer of the tested layers against APV and HEV increased with the age of the birds. The lowest antibody titer (GMTAPV=24818; GMTHEV=12070) was observed at the beginning of the laying period, and the highest at the end of the laying period (GMTAPV =38978; GMTHEV =13980). The highest vertical transfer to offspring was shown for antibodies to - HEV (82.7%), while the lowest was shown when analyzing sera to - NDV (37.6%). The present analysis showed significant differences in the evaluated antibody titres in serum of turkey breeders during the laying period, as well as in the level of MatAb in chicks. The results also indicate that the transfer of MatAb to chicks is influenced by the age of the parent flock and the type of pathogen against which the layers were vaccinated.