Department of Animal Breeding and Genetics, College of Veterinary Sciences, Punjab Agricultural University, Ludhiana-141 004 (Punjab)
The study was conducted on two selected and a control line of White Leghorns consisting of a total of 1733 pullets. The differences between the two selected strains for comb height and comb width recorded at 16, 32 and 40 weeks of age were non-significant though the two strains differed significantly for most of the egg productivity traits. Wattle length of the high producing strain was, however, significantly more than the control line just prior to onset of egg production (16 weeks of age). Selection for egg production led to increase in the comb and wattle measurement. Heritability of comb and wattle measurements at early age was moderate to high (0.48±0.19 to 0.95±0.23) but at later stages these were lower (0.13±0.14 to 0.48±0.19). Comb and wattle measurements were highly correlated between 32 and 40 weeks of age but the genetic correlations for the 16week comb and wattle measurements with these measurements at subsequent stages were low. Genetic correlation between the three measurements was higher at 16 and 32 weeks of age (0.38 to 0.89) than at 40 weeks of age (0.069 to 0.39). Age at sexual maturity and egg number to 40 weeks of age had desirable genetic correlation with comb and wattle measurements at 16 weeks of age (−0.43 to −0.88 for ASM and 0.46 to 0.75 for EN). The genetic correlations of these measurements at 16 weeks of age with egg mass and efficiency index were positive and desirable (0.36±0.12 to 0.71±0.05).
Comb height, comb width, wattle length, body weight, egg production, White Leghorn
