Impact of crossing Fayoumi and Leghorn chicken breeds on immune response against Newcastle disease virus vaccines.

This study was conducted to evaluate the immune response against Newcastle disease (ND) virus vaccines (live attenuated and inactivated) in purebred Lohman Selected Leghorn (LSL), Fayoumi, male Fayomi × female LSL (FL crossbred), male LSL × female Fayomi (LF reciprocal crossbred) chickens. One-hundred-day-old chicks of each genetic type were assigned to five equal replicates. The log geometric means of the hemagglutination inhibition (HI) antibody titers were calculated. The FL crossbred chickens had a significantly higher HI antibody titer at day 26 of age when compared with the LSL chickens (P = 0.039). The Fayoumi and FL crossbred chickens had significantly higher HI antibody titers at day 45 of age (2.35 and 2.23, respectively) when compared with the LSL chickens (P = 0.031). In the same way, the purebred Fayoumi and FL crossbred chickens had significantly higher HI antibody titers at 60 and 75 days of age (P = 0.009 and 0.041, respectively) when compared with the purebred LSL and LF crossbred chickens. The LSL chickens showed a significantly higher (P < 0.05) correlation estimate between HI titer to the ND vaccine on day 75 of age and body weight at week 12 of age. When challenged with the virulent ND virus, the hazard ratio (HR) for mortality rates in purebred LSL and LF crossbred chickens were significantly (HR = 3.52 and 2.07; P = 0.001 and 0.049, respectively) higher than the Fayoumi chickens. In conclusion, purebred Fayoumi and FL crossbred chickens showed superior antibody titers against live attenuated and inactivated ND virus vaccines. Hence, Fayoumi breed may be incorporated in the crossbreeding programs to improve the genetic resistance to ND.