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Table 3 Descriptive statistics and unconditional associations of continuous variables selected as candidates for multivariable model for within-herd cow mortality rate in years 2017–2018 in 212 Estonian dairy herds estimated in linear regression analysis

From: Herd-level risk factors for cow and calf on-farm mortality in Estonian dairy herds

VariableMedian (Q1; Q3)np-valuea
Herd size (number of cows)129.7 (53.7; 459.7)212 < 0.001
Herd average milk yield per cow per year (kg)8787 (6950; 9758)2120.002
Herd average milk fat/protein ratio1.2 (1.2; 1.3)2120.001
Herd average age at first calving (days)813.0 (764.3; 888.7)2120.024
Herd average interval from calving to insemination (days)92.3 (79.6; 111.7)2040.061
Herd average number of inseminations per conception1.9 (1.7; 2.2)2040.004
Herd average first insemination conception rate (%)53.9 (47.2; 60.6)2040.003
Herd proportion of stillbirths (%)7.5 (5.6; 9.5)2120.008
Herd proportion of abortions (%)0.8 (0; 1.6)2120.022
Herd average number of lactations2.4 (2.2; 2.7)212 < 0.001
Herd average age at first insemination (days)498.7 (457.3; 585.7)1870.123
  1. aEstimated in bivariable linear regression models including herd number of cows to that category