Abstract
Layer performance intensively rely on their genetic pool and feeding strategies. Researchers could alter genetic makeup through genetic crossing techniques, which reflects on the birds requirements and performance including productivity immunological response. Four hundred female pullets at 18 weeks of age were divided into four groups of one hundred pullets each; Hajar(1) (H-1), Hajar(2) (H2), female H-1 crossed with male Hi-Sex (H1HI), and H-2 crossed with Sex (H2HI). Birds randomly assigned into 4 groups with 20 replicates of 5 birds. Humoral immune response against Newcastle disease (ND) and egg production performance of recently characterized chicken lines in Saudi Arabia, H-1, H-2, H(1)H1, H2HI lines were determined. The evaluation of the hybrid performance was reflected on the actual requirements and potential of those lines in a very important period in the chicken life. The laying hens were evaluated for general performance including egg production, mortality rate, and egg characteristics, as well as Newcastle disease (ND) antibody titer. The results of current investigation showed that egg production, egg mass and feed efficiency were significantly better (P<0.05) in H2HI group, while egg weight was significantly greater (P<0.05) in H2HI group. In addition, the data of humoral immune response against ND in the four lines showed that all breeds suffered from limited protection. In conclusion, the cross line breeds (H1HI and H2HI) showed higher improvement in the productive performance compared to native Saudi local breeds (H-1 and H-2) without jeopardizing their immunity response.