Heritabilities and genetic correlations of egg production and other characters in a White Wyandotte flock

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Abstract
Five years' records of unculled White Wyandotte flocks at Hillsborough, Northern Ireland, were analysed to give estimates of heritabilities and of genetic and environmental correlations by two methods. Pooling data for four years and eliminating hatch effects gave heritabilities of 0·28 for eggs laid by survivors to 500 days; 0·61 for weight of pullets at penning; 0·51 for weight of pullets at 8 weeks; 0·18 for days to first egg; and 0·71 for spring egg weight. These are in general agreement with most other published figures, as are most of the genetic correlations. A suggestion of sex-linkage in the genetic correlations between weight at 8 weeks and days to maturity was not supported by other figures from the data. The method of eliminating hatch effects, unexpectedly, gave higher heritability figures where heritability was already moderate or high. It gave numerically greater figures in most genetic correlations, but did not lead to an expected reduction in the environmental correlations. The data were probably inadequate for a rigorous test of the method.