Data collection on group housed animals generally happens at the individual animal level. However, sometimes it is too difficult or expensive to obtain individual records. Alternatively, data collection happens at group level, e.g. egg production. Bivariate analyses of individual and pooled data are complex, especially for traits affected by social interactions. We found that to avoid bias, a random group effect for pooled data needs to be added, fixed and correlated to the random group effect for individual data. This adjusted model was used to estimate the genetic correlation between survival (individual records) and early egg production (pooled records) in crossbred laying hens. The correlation was -0.09. This deviates from the correlation of 0.14 that was found with the unadjusted model, showing the magnitude of the bias.
Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume Species Breeding: Poultry (Posters), , 856, 2014
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