Heterosis, recombination effects and genetic variability of egg composition in inbred lines of white leghorns and their crosses

Positive heterosis effects for the proportion of yolk, and negative heterosis for the proportion of albumen were found in crosses of six inbred Leghorn lines.2. Three‐way crosses showed no consistent change in egg composition when compared with matched two‐way crosses.3. Large differences in egg composition were found between inbred lines.4. The egg composition of two‐way crosses was highly predictable from the performance of their parents, while specific combining effects as measured by deviations from offspring—parent regression were relatively unimportant.