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Table 3 Results of multivariable random-effect Weibull model for risk factors of culling in 85,765 primiparous dairy cows (herds n = 389)

From: Culling reasons and risk factors in Estonian dairy cows

Variable

Category

Na,b

Hazard Rate Ratio

95% Confidence Intervals

P-value

Likelihood ratio test p-value

Animal level variables

Breeda

Estonian Holstein

70,508

1

  

0.018

Estonian Red and Estonian Native

15,257

0.92

0.85; 0.98

0.018

 

Relative milk yield breeding valuea

< 90

17,622

1

  

< 0.001

90–96

20,022

0.66

0.63; 0.71

< 0.001

 

97–104

18,065

0.48

0.45; 0.52

< 0.001

 

≥105

21,320

0.37

0.35; 0.40

< 0.001

 

Not estimated

8736

14.50

13.74; 15.31

< 0.001

 

Calving yeara

2013

27,904

1

  

< 0.001

2014

29,368

1.01

0.97; 1.06

0.536

 

2015

28,493

0.90

0.85; 0.94

< 0.001

 

Calfa

Female

38,482

1

  

< 0.001

Male

36,502

1.04

0.996; 1.081

0.080

 

Stillbirth

9972

1.45

1.37; 1.54

< 0.001

 

Twins/triplets

480

1.31

1.05; 1.63

0.015

 

Abortion

329

0.67

0.50; 0.91

0.011

 

Assisted calving x periodb

No, < 7 days

70,351

1

  

< 0.001

No, > 7 days

69,176

1.13

1.04; 1.23

0.004

 

Yes, < 7 days

15,414

2.10

1.81; 2.36

< 0.001

 

Yes, > 7 days

14,939

1.34

1.22; 1.48

< 0.001

 

Age at first calving (months) (centered)

  

1.07

1.06; 1.07

< 0.001

< 0.001

Square term centered value of age at first calving (months)

  

0.99

0.994; 0.995

< 0.001

< 0.001

Herd-level variables

Change of herd size from 2013 to 2015a

No change (±5%)

39,143

1

  

< 0.001

Decrease > 5 to 15%

12,904

1.28

1.001; 1.631

0.049

 

Decrease > 15%

8499

1.56

1.22; 2.00

< 0.001

 

Increase > 5 to 15%

13,591

0.79

0.62; 1.01

0.060

 

Increase > 15%

11,628

0.61

0.47; 0.80

< 0.001

 

Herd average number of cows (increase by 50 cows)

  

1.04

1.02; 1.05

< 0.001

< 0.001

Herd average interval from calving to insemination (days)

  

0.99

0.985; 0.992

< 0.001

< 0.001

Herd average first insemination conception rate (%)

  

1.01

1.01; 1.02

< 0.001

< 0.001

Herd average number of lactations (years)

  

0.41

0.33; 0.51

< 0.001

< 0.001

Regiona,c

North-East

36,651

1

  

0.018

South-East

17,235

0.85

0.71; 1.02

0.086

 

South-West

19,091

1.14

0.98; 1.32

0.087

 

North-West

12,788

1.04

0.87; 1.24

0.665

 
  1. Shape parameter p = 0.82
  2. anumber of animals in each category
  3. bnumber of observations in each category after splitting the observations in 7th day post-calving
  4. cNortheast Estonia: Ida-Viru, Lääne-Viru, Jõgeva, Järva county; Southeast Estonia: Tartu, Valga, Võru, Põlva county; Southwest Estonia: Pärnu, Viljandi, Saare county; Northwest Estonia: Harju, Rapla, Lääne, Hiiu county
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BMC Veterinary Research

ISSN: 1746-6148

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