Genetic determination of immune responses to Newcastle disease virus vaccine in chickens
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Date
2002
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Sokoine University of Agriculture
Abstract
A study was conducted at Sokoine University of Agriculture to investigate the genetic
control of immune response of chickens against Newcastle disease virus (NOV) vaccine.
The study involved local chickens from Tanzania (LL), Rhode Island Red derivative
hybrids (EE), and their reciprocal crosses (LE and EL). The local ecotype had the
highest mean antibody titres following primary vaccination, as well as before (residual)
and after secondary vaccination, while the exotic breed had the lowest titres in all three
measurements. The crossbred chicks were found to be intermediate between the two
parental genotypes, but the differences between the local ecotype and the crosses were
not significant except for the primary vaccination antibody titre. Furthermore, there were
no significant differences between the reciprocal crosses. Differences between sexes
were not significant. Despite the observed superiority of the local ecotype for antibody
titre, there were no significant differences among genotypes with respect to mortality
rate. Heritability estimates for antibody titre ranged from 0.27 ± 0.06 to 0.39 ± 0.09,
0.17 ± 0.03 to 0.32 ± 0.11, and 0.18 ± 0.08 to 0.28 ± 0.08 for antibody titre following
primary vaccination, before, and after secondary vaccination, respectively. While the
contribution of additive breed merit and heterosis effects in antibody titre before and
after secondary vaccination were both significant, only the contribution of additive breed
merits were significant for primary immune response. There were no significant
correlation coefficients between antibody titres at different periods of measurement, nor
between antibody titres and body weights. It was concluded that substantial
improvement in immunological status of a stock against Newcastle disease could be achieved through both selection and crossbreeding
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Keywords
Genetic determination, Immune Responses, Newcastle disease virus, Vaccine, Chickens