Table 3.
Means and standard deviation (SD) of the egg production traits of generations G4 and G5 hens, and the selected G4 dams and sires of the G5 hens.
| Trait | G4 |
G5 All hens | G5mG44 | SD |
|||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| All hens | Selected dams | Selected sires1 | Mid-parents2 | SelDif 3 | G4 all | G4 dams | G4 sires | G5 all | |||
| %Pause5 (%) | 52.8b | 47.4b | 40.2c | 43.8 | −9.0* | 75.6a | 22.8⁎⁎⁎ | — | — | — | — |
| PsDays (d) | 19.0b | 13.3c | 11.7c | 12.3 | −6.7⁎⁎ | 31.8a | 12.8⁎⁎⁎ | 24.3 | 17.8 | 9.3 | 25.6 |
| AFE (d) | 152.3b | 150.7b | 151.9b | 151.5 | −0.8 | 154.8a | 2.5* | 15.1 | 13.3 | 9.8 | 14.8 |
| EN300 (eggs) | 84.5b | 93.1a | 94.4a | 94.1 | 9.6⁎⁎⁎ | 78.7c | −5.8⁎⁎⁎ | 25.0 | 18.9 | 12.7 | 23.8 |
| %L300 (%) | 57.0b | 62.4a | 63.9a | 63.5 | 6.4⁎⁎⁎ | 54.1c | −2.9⁎⁎ | 15.5 | 11.4 | 8.5 | 15.1 |
| %Lnet (%) | 65.0b | 68.3a | 69.0a | 68.8 | 3.8⁎⁎⁎ | 69.0a | 4.0⁎⁎⁎ | 11.4 | 8.3 | 6.2 | 10.4 |
| ClLng (d) | 2.77b | 2.95ab | 3.21a | 3.10 | 0.33* | 3.10a | 0.33⁎⁎⁎ | 1.22 | 1.18 | 1.09 | 1.45 |
| EW200 (g) | 40.9b | 41.5a | 41.8a | 41.7 | 0.8* | 41.9a | 1.0⁎⁎⁎ | 3.0 | 2.6 | 1.6 | 3.0 |
| EW300 (g) | 47.4b | 48.0a | 48.5a | 48.2 | 0.8* | 48.4a | 1.0⁎⁎⁎ | 3.6 | 3.2 | 2.1 | 3.6 |
Differences between these means represent the selection differentials in G4, and the responses to the selection.
%Pause, percentage of hens with Pause; PsDays, number of Pause days until 300 d; AFE, age at first egg; EN300, number of eggs laid until 300 d; %L300, overall laying rate from AFE to 300 d; %LNet, laying rate during in-lay days; ClLng, average clutch length; EW200, average egg weight around 200 d; EW300, average egg weight around 300 d.
Each sire was assigned the means of his 3-to-5 full-sib sisters.
Mid-Parents is the average of the dam and sire of each G5 hen.
SelDif: the selection differential, i.e. the difference between the Mid-parents mean and the mean of all the hens in G4.
G5mG4: the mean of all G5 hens minus the mean of all G4 hens.
The differences in %Pause between groups were tested by Chi-square test of the numbers of hens with Pause or without Pause in each group.
For each trait, means with no common superscript, differ significantly at P < 0.05.
*,**,***The parameter (SelDif, G5mG4) estimate significantly different from zero at P < 0.05, P < 0.01, and P < 0.001, respectively.