Department of Animal Genetics & Breeding, College of Veteringly Science & Animal Husbandry, CS Azad University of Agriculture & Technology, Mathura Campus, Mathura - 281 001.
1 Animal Science Division, CARI, Port Blair - 74: 101, A & N Islands.
A total of 2263 pullets of 127 sires and 1046 dams of 7 consecutive generations were studied. Females on the basis of their first hundred days egg production (EP 100) and cocks on the basis of their sire family averages for EI 100 were selected every generation. The average correlated phenotypic response of egg production upto 280 days of age (EP280), egg weight (EW) and percent rate of lay (RL) were positive but not significant, while, for average pause size (PS) it was negative and not significant. The pooled heritability estimates of EP280 and EW were moderate, while for RL, it was low and for PS, it was very low. The time trend of heritability estimates of EP280 and PS were negative and not significant, while, for EW and RL it was positive and not significant. The pooled estimates of genetic correlations of EP280 with EW and PS were negative and significant (P<0.01), while, with RL it was positive and significant (P<0.01). The pooled estimates of genetic correlation of EW with PS and RL and between PS and RL were all negative and signif1cant (P<0.01). The pooled estimates of environmental and phenotypic correlation between EP280 and PS, EW and PS and PS and RL were all negative, while, between other combinations of traits these estimates were positive. The time trends of estimates of environmental and phenotypic correlation between EP280 and PS and between PS and RL were negatively significant. The time trends of phenotypic correlation between EW and RL was negatively significant.
Time trends, average phenotypic response, White Leghom
