Heritabilities and genetic correlations for monthly egg production and egg weight of White Leghorn hens estimated based on hen-housed and survivor production

A total of 2362 hens (line A), offspring of 79 sires and 642 dams and 2728 hens (line D), offspring of 80 sires and 671 dams were used to estimate the genetic parameter of monthly egg production and egg weight based on survivor production (SP) and hen-housed production (HHP). (Co) variance components were estimated using VCE 4 programme (GROENEVELD, 1998) based on REML method with a multivariate animal model. The heritability estimates for monthly egg production based on SP ranged from 0.08 to 0.44 and 0.04 to 0.43 for the two lines and those based on HHP varied from 0.01 to 0.44 and 0.01 to 0.43. Heritability for total egg production based on SP were 0.32 ± 0.04 (line A) and 0.29 ± 0.03 (line D) and those based on HHP were 0.11 ± 0.02 (line A) and 0.08 ± 0.02 (line D). Between monthly egg productions and total egg production the genetic correlations ranged for SP from 0.21 to 0.95, for HHP from 0.09 to 0.95. Egg weight showed higher estimates for heritability, 0.39 to 0.54 and 0.40 to 0.54 for SP and HHP, respectively. The results indicate that estimation based on survivor production tend to give higher estimations of genetic parameters for monthly egg production than those based on hen-housed production. It seems to be more useful to use data based on SP for estimating genetic parameter than using data based on hen-housed egg production.