The first objective of this study on broiler breeders was to investigate the genetic basis of variability in hatchability over age using a longitudinal model. Weekly percentage hatch of fertile and hatch of set eggs were available for 23,250 dams mated to 3,106 sires of the same age between the 28th and 54th week of life. Hatch of set was very highly correlated with fertility and showed a similar pattern through lay. There was a genetic contribution of the dam but not the sire to hatch of fertile; its heritability was about 6% from peak lay onward but lower earlier. The second objective was to investigate the relationship between hatchability and internal and external egg quality traits measured at 48 wk of age. These traits, specific gravity, weight loss, egg weight, and Haugh units, had moderate to high heritabilities, 0.53, 0.38, 0.65, and 0.38, respectively. Parameters of the genetic trend in weekly hatchability (mean and persistency) were significantly correlated with these egg quality traits, suggesting that in a bulk mating situation in which individual recording of hatchability is not possible, these quality traits could provide some indication on the trend in flock hatchability.
- egg quality
- random regression