Table 1 Differences in laying performance and eggshell qualities of the hens laying eggs with different eggshell breaking strength^a

Laying performance

 Egg production rate, %

89.35 ± 2.75

86.37 ± 3.88

0.060

 Egg mass, g/hen/d

56.36 ± 2.54

55.36 ± 3.76

0.456

 Average egg weight, g

63.19 ± 1.69

64.16 ± 2.30

0.250

 Average daily feed intake, g/hen/d

107.74 ± 6.31

105.43 ± 5.78

0.360

 Feed conversion ratio, g/g

1.92 ± 0.16

1.91 ± 0.15

0.938

Eggshell quality

 Breaking strength, N

46.79 ± 2.56

25.99 ± 2.51

< 0.001

 Eggshell thickness, mm

0.35 ± 0.02

0.30 ± 0.03

< 0.001

 Eggshell weight, g

6.59 ± 0.42

5.85 ± 0.41

< 0.001

 Eggshell weight ratio, %

10.42 ± 0.42

9.13 ± 0.54

< 0.001

Eggshell components

 Ca content, mg/g

374.64 ± 7.32

378.27 ± 7.67

0.229

 Total Ca per eggshell, g

2.47 ± 0.10

2.19 ± 0.08

< 0.001

 P content, mg/g

0.96 ± 0.09

0.94 ± 0.11

0.619

 Total P per eggshell, mg

6.29 ± 0.57

5.49 ± 0.73

0.007