Impact of family-based selection on growth performance and immune response of Japanese quail.

The present study was aimed to evaluate the growth performance and immune response of three genetic lines of Japanese quails. These lines i.e., selected for 4-week body-weight group (WBS), selected for egg number (EBS), and random-bred control (RBC), were selected for three consecutive generations from a base population of 1125 quails. In total, 2700 four-week-old quails from three selected groups were slaughtered in total of four generations (G0 to G3). Effects of selection and generations as well as their interactions were assessed for growth performance and immune response by applying a two-way analysis of variance. Significant means were compared with Duncan's Multiple Range Test. The statistical analysis showed a significant effect of selection and generations on most of the growth and immune response parameters. WBS in G3 presented significantly higher values of body weight, weight gain, and FCR than RBC and EBS. FCR was better in WBS during G3 than those of EBS and RBC. However, Livability% was highest in RBC while the lowest was noted in G3 of WBS line. Thymus% and spleen% were higher in EBS as compared to RBC and WBS. RBC presented a better B/S ratio and ND titer than those of EBS and WBS. The decreasing trend of ND titer in both lines of WBS and EBS as compared to RBC suggested a decrease in New Castle disease resistance in progressive generations of selection. It was concluded that selection for body weight and egg number has a positive impact on respective traits but negatively affects the immunity in later generations.