Table 6 Results from multivariable linear regression models of the associations between predictors and concentration of β-carotene

Model feed β-carotene (mg/kg DM)^a (n = 57)

 Constant

3.50

0.10

< 0.001

3.28–3.72

 First harvest in feed sample

No

Baseline

–

–

–

Yes

0.64

0.17

0.001

0.29–1.00

 Region

Halland/Skåne

Baseline

–

–

–

Skaraborg

0.38

0.17

0.034

0.032–0.73

 TMR^b

No

Baseline

–

–

–

Yes

− 0.99

0.14

< 0.001

− 1.28 to − 0.70

 Type of herd^b

LM

Baseline

–

–

–

HM

− 0.15

0.17

0.38

− 0.51 to 0.20

Model colostrum β-carotene (µg/mL)^a (n = 162)

 Constant

− 2.81

0.38

< 0.001

− 3.6 to − 2.02

 Breed

SR

Baseline

–

–

–

SH/MB

0.69

0.25

0.013

0.16 to 1.21

 Fat^c (%)

0.26

0.27

< 0.001

0.20 to 0.32

 Interaction: fat (%) × breed

Fat^c (%) × breed SR

Baseline

–

–

–

Fat^c (%) × breed SH/MB

− 0.11

0.036

0.005

− 0.19 to − 0.038

 Total solids (Brix%)

0.048

0.016

0.007

0.015 to 0.081

 Type of herd^b

LM

Baseline

–

–

–

HM

− 0. 62

0.16

0.69

− 0.39 to 0.26

Model cow serum β-carotene (µg/mL) (n = 189)

 Constant

4.28

0.21

< 0.001

3.85–4.71

 Breed^b

0.0003

SR

Baseline

–

–

–

SH

− 1.27

0.25

< 0.001

− 1.78 to − 0.75

MB

− 0.55

0.32

0.10

− 1.23 to 0.12

 Percentage maize silage (DM) of total ration

< 20%

Baseline

–

–

–

≥ 20%

− 1.08

0.27

0.001

− 1.66 to − 0.50

 Type of herd^b

LM

Baseline

–

–

–

HM

0.16

0.27

0.56

− 0.41 to 0.73

Model calf serum β-carotene^a (µg/mL; n = 187)

 Constant

− 1.84

0.08

< 0.001

− 2.01 to − 1.67

 Breed^b

SR

Baseline

–

–

–

SH/MB

− 0.06

0.12

0.61

− 0.31 to 0.018

 Interaction: breed × total protein (g/L)

0.036

SR × total protein ≥ 55

Baseline

–

–

–

SR × total protein < 55

− 0.21

0.11

0.078

− 0.44 to 0.026

SH/MB × total protein ≥ 55

− 0.062

0.12

0.61

− 0.31 to 0.18

SH/MB × total protein < 55

− 0.78

0.15

< 0.001

− 1.08 to − 0.047

 Total protein (g/L)

≥ 55

Baseline

–

–

–

< 55

− 0.21

0.11

0.078

− 0.44 to 0.026

 Type of herd^b

LM

Baseline

–

–

–

HM

− 0.18

0.15

0.23

− 0.49 to 0.12