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Table 2 Results of multivariable negative binomial regression analysis for risk factors associated with within-herd calf (aged 21–90 days) mortality rate in years 2017–2018 in 209 Estonian dairy herds

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

VariableCategoriesnIRRa95% confidence intervalsCategory p-valuep-value
Herd size (centered) (number of cowsb)  1.021.01; 1.03 0.005
Square term of herd size (centered)  0.99970.9995; 0.9999 0.001
Herd proportion of stillbirths (%)  1.091.04; 1.14  < 0.001
Herd proportion of abortions (%)  1.221.09; 1.36  < 0.001
RegioncNortheast591  0.020
Southeast440.630.44; 0.900.013 
Southwest711.100.79; 1.530.573 
Northwest351.010.68; 1.520.946 
Farmer attending trainings within the last 4 yearsOnce481  0.008
2–3 times1071.911.30; 2.810.001 
More than 3 times311.340.83; 2.190.233 
No231.090.57; 2.080.792 
Prophylactic administration of vitamins to calvesNo701  0.041
Sometimes621.190.83; 1.690.337 
Yes (to more than 95% of calves)771.481.09; 2.010.012 
Housing of preweaned calves > 2 weeks of ageGroup pen1681  0.020
Single pen181.170.67; 2.030.581 
Single and group pen230.510.32; 0.830.007 
Place of calvingGroup pen681  0.020
Individual pen410.830.59; 1.170.284 
Tiestall841.130.79; 1.610.510 
Combined or otherd160.400.20; 0.780.008 
  1. aIncidence rate ratio
  2. bOne unit change is 20 cows
  3. 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
  4. dOther: calving on pasture and its combinations between other systems