Genetic relations of yolk proportion and chick weight with production traits in a White Leghorn line

1. The main purpose of this study was to estimate genetic correlations between yolk proportion, chick weight and production traits using an animal model. 2. Direct-direct genetic correlations were estimated between yolk proportion and age at first egg (-0·34), body weight at 20 (0·10), 40 (0·58) and 60 (0·52) weeks of age, egg number (0·56), egg mass (0·59), feed intake (0·64) and feed conversion (-0·25). 3. Maternal-direct genetic correlations were estimated between chick weight and age at first egg (0·40), body weight at 20 (0·57), 40 (0·66) and 60 (0·56) weeks of age, egg number (-0·50), egg mass (0·21), feed intake (0·45) and feed conversion (0·17), respectively. 4. In conclusion, the results suggest that selection on a higher yolk proportion would not have any unfavourable effects on egg production. Maternal-direct genetic correlations between chick weight and production traits resembled direct-direct genetic correlations between egg weight and production traits found in other studies.