Table 5 Factors affecting BMD were screened by multivariate ordinal logistic regression analysis

Intercept 2

− 2.80

0.50

–

–

–

< 0.001

Intercept 1

1.66

0.49

–

–

–

0.001

Line

0 = Chinese line

0.21

0.22

1.24

− 0.21

0.64

0.32

1 = American line ^{ref 4}

0⁵

0

0

0

0

–

Age

1 =  ≤ 12

2.22

0.42

9.19

1.39

3.05

< 0.001

2 = 13–24

2.16

0.33

8.66

1.50

2.81

< 0.001

3 = 25–36

1.48

0.35

4.41

0.79

2.18

< 0.001

4 =  ≥ 37

0

0

0

0

0

–

Body weight, Kg

1 =  ≤ 200

− 0.13

0.50

0.88

− 1.11

0.86

0.80

2 = 201–250

0.07

0.41

1.08

− 0.74

0.88

0.86

3 = 251–300

− 0.24

0.33

0.79

− 0.88

0.41

0.47

4 =  ≥ 301

0

0

0

0

0

–

Backfat, mm

1 =  ≤ 12

− 1.60

0.56

0.20

− 2.70

− 0.51

0.004

2 = 13

− 1.38

0.48

0.25

− 2.31

− 0.45

0.004

3 = 14

− 1.38

0.46

0.25

− 2.29

− 0.48

0.003

4 = 15

− 1.77

0.46

0.17

− 2.67

− 0.88

< 0.001

5 = 16

− 2.25

0.45

0.11

− 3.12

− 1.37

< 0.001

6 = 17

− 1.62

0.49

0.20

− 2.58

− 0.67

0.001

7 = 18

− 1.40

0.48

0.25

− 2.34

− 0.46

0.004

8 =  ≥ 19

0

0

0

0

0

–

Serum Ca, mg/dL

1 =  ≤ 8

0.60

0.27

1.82

0.07

1.13

0.03

2 = 8–11

− 0.13

0.18

0.88

− 0.48

0.23

0.48

3 =  ≥ 11

0

0

0

0

0

–

Serum P, mg/dL

1 =  ≤ 4

− 0.71

0.34

0.49

− 1.38

− 0.05

0.04

2 = 4–9

− 0.26

0.28

0.77

− 0.81

0.29

0.36

3 =  ≥ 9

0

0

0

0

0

–