Modelling genetic components of hatch of fertile in broiler breeders

ABSTRACT Reproductive efficiency such as fertility and hatch of fertile (HoF) are of economic importance and of concern to breeding companies due to their effects on chick output. Like other traits of economic importance in poultry breeding, the rate of response for HoF is largely dependent on the use of an appropriate model to evaluating the trait. Therefore, the objectives of this study were to estimate genetic parameters from cumulative, repeatability, fixed regression, random regression and multi traits models for HoF from a pure-line broiler breeder. The data available for this study consisted of weekly HoF records from 11,729 hens with a total pedigree record of 38,260. Estimates of heritability from the various models, ranged from 0.04-0.22 with the highest estimate obtained from the cumulative model and the lowest from the repeatability model. Responses to selection estimated for the different models ranged from 0.03 – 0.08% gain per year of the phenotypic mean. In general, the cumulative and the repeatability models underestimated response to selection. The multi trait and random regression models gave similar results for response to selection at 0.08 percentage change in phenotypic mean. In conclusion, the cumulative model is not optimal for modelling HoF and likewise the repeatability model. The random regression and multi trait models should be considered instead as they offered a higher response to selection. However, if a multi trait analysis is to be considered, it is recommended to split up the production period in such a way as to avoid computational constraints due to over parameterization.