Relationship of early laying, number and weight of laid eggs to fertility and hatchability of eggs in initial laying lines of hens

The relationships between age of hens, number of laid eggs, egg weight on one hand and fertility and hatchability on the other were analysed during two periods of individual pedigree hatching. Altogether 1 369 hens originated from 9 selected initial laying lines of Bar Plymouth Rock (BPR) (3 lines), Rhode Island Red (RIR) (4 lines), Rhode Island White (RIW), and Sussex Light (SUL) breeds. A total number of 23 473 eggs from hens of all 9 aforementioned lines were set after being artificially inseminated. The total average hatchability of set eggs was 73.2 % and the average percentage of unfertilised eggs was 9.3 %. Positive correlations (rp =0.22 to rp =0.72; P