GROUPING CHICKENS INTO RESISTANT AND SENSITIVE TO STRESS ON THE BASES OF HETEROPHIL/LYMPHOCYTE RATIO FOR GENETIC AND IMMUNOLOGICAL STUDIES

1- The Heterophil/Lymphocyte ratio (H/L) was used to separate chickens into Resistant (R) and Sensitive (S) to S.typhimurium, using the 99% lower confidence limit for selection. 2- Five groups of chickens were constructed, 20 each, varying the number of R and S in each group, from all R, (15R+5S), (10R+10S), (5R+15S) and all S. Mean H/L ratio, before and 9 day post Salmonella typhimurium infection were compared. 3- Difference in H/L ratio group means, within before and after infection were significant due to different constructions. 4- Comparison of before and after H/L mean, within each group, showed a different outcome according to group construction. 5- It was concluded that individuals should be separated into R and S, using the H/L ratio as an indicator and criterion for selection for resistance before grouping the chickens for genetical and immunological studies.