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CHAPTER 6
compared with second (115-125 d) and older parity cows (119-128 d, P < 0.0001). As in
the DIMFI model, the highest producing cows in the herd had a longer DIMCONC
compared to their lower producing herdmates (P < 0.0001). Pure Holstein cows had a 5
d larger DIMCONC (119-126d) compared to crossbred Holsteins (112-121 d, P = 0.0042).
Other breeds showed an intermediate DIMCONC (111-129 d).
Table 4. Final multivariable linear regression model of log10 transformed days to
conception, based on 5,839 cows that conceived on 90 Belgian herds in 2008 and
2009 using herd as random effect in the model (λ = 0.0024, SE = 0.00057, P < 0.0001)
Covariate Class β 1 SE P-value
Cow level
Parity 1 -0.032 0.0067 2 Ref. 2
Breed 100% HF 3 0.0094 0.01763 0.0166
50% HF -0.0114 0.01796
Other Ref.
Relative M305 4 , % Cont. 5 0.002967 0.00018