Genetic analysis of productive and reproductive traits in White Leghorn chicken

Data on age at first egg (AFE), body weights, egg production and egg weights at different ages were collected on 1665 birds pertaining to 4 genetic groups of White Leghorn chicken. Significant hatch effects were adjusted before estimating genetic parameters. All the production traits studied were found to be significantly different among the genetic groups studied. The average AFE was shortest in IWH (143.49) and longest in IWK (155.63 d). Body weights at 40, 52 and 64 weeks were highest in control population while IWK strain had lowest body weights at 40 and 52 weeks. Egg production was highest in IWH and lowest in IWK strains. Egg weight at all ages was highest in IWK strain.

The heritability estimated from dam component was higher than that from sire component. In general, the genetic correlations of AFE with body weights were mostly positive and medium to high while that with egg production traits was high but negative. AFE was positively correlated at genetic level with egg weights. The phenotypic correlation of AFE with body weights varied among the strains but was mostly positive. The genetic and phenotypic correlations among body weights were positive while the genetic correlations with 40, 64 and 72 weeks egg production were mostly negative. The phenotypic correlation with BW64 and egg weights at different age was positive and high while the correlation with egg production at 40, 64 and 72 weeks was mostly negative. The correlation with EP40 and EP72 was mostly positive. The genetic and phenotypic correlations with egg weights were inconsistent among the strains. The correlations of BW64 with egg production were mostly negative while those with egg weight were mostly positive with moderate to high magnitude. The correlation with egg weight varied among the strains. The genetic correlation among egg production traits was positive and high in general. The genetic correlation of EP64 with EP72 was positive and very high. The genetic correlation between egg production and egg weight was mostly negative and moderate to high in magnitude while they were all positive at phenotypic level. The results indicated that heavier hens at later ages produced less number of eggs which are of larger size. The present study revealed that there is sufficient amount of genetic variation available in the populations for most of the characters studied to bring about improvement in these traits through further selection.