Genetic Parameters for Production Traits of Rhode Island Red and White Plymouth Rock Breeds Selected under Tropical Condition in Thailand

Egg production data on Rhode Island Red and White Plymouth Rock hens selected for 11 generations under a tropical environment in Thailand were used to estimate genetic parameters for age at first eggs (AFE), body weight at first eggs (BFE), weight of first eggs (WFE), egg production from 1st day to 17 weeks of lay (EGG) and average egg weight at 17th week of lay (EWT). Estimated heritability for AFE, BFE, WFE, EGG and EWT of RIR hens were 0.46, 0.51, 0.28, 0.33 and 0.47 and for WPR hens these were 0.44, 0.41, 0.33, 0.30 and 0.43, respectively. AFE is positively correlated with BFE, WFE and EWT and negatively correlated with EGG in both breeds. EGG was negatively correlated with both WFE and EWT in both breeds. The estimated genetic parameters will be used in selection strategies to improve the productivity of both breeds.