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. 2020 Jun 30;14(12):2619–2627. doi: 10.1017/S1751731120001548

Table 3.

Models showing how different management strategies affect milk yield of dairy cows on-farm

Variable Model 1: no weight1 Model 2: weight by N2 Model 3: remove missing3 Model 4: replace missing4
Est SE P-values Est SE P-values Est SE P-values Est SE P-values
Intercept 7.91 1.31 <0.001 6.85 0.86 <0.001 7.57 1.46 <0.001 7.79 1.41 <0.001
Days in milk −0.02 0.00 <0.001
Calf suckling −2.06 0.60 <0.001
Trial length −0.01 0.00 0.004 −0.01 0.00 0.056 −0.01 0.00 0.020
Improved cattle breeds 2.79 0.54 <0.001 2.11 0.36 <0.001 2.43 0.63 <0.001 2.53 0.52 <0.001
Improved feeding 0.40 0.73 <0.001 1.25 0.46 0.007 1.89 0.34 <0.001 0.06 0.84 <0.001
Maximum temperature −0.13 0.04 <0.001 −0.12 0.05 <0.001 −0.11 0.04 0.010
Imp. catt. breeds × Imp. feeding5 1.48 0.78 0.06 1.94 0.88 0.03
Fit statistics
 N 102 119 92 102
 Observed mean 6.37 6.97 6.52 6.37
 Predicted mean 6.37 9.95 6.45 6.31
 RMSE, % mean 15.82 17.2 16.4 16.20
 Mean bias, % MSE 0.00 0.02 0.42 0.38
 Slope bias, % MSE 0.48 1.07 0.72 0.03
 RSR 0.81 1.08 0.83 0.80
 CCC 0.93 0.92 0.93 0.93
2.19 3.34 2.33 2.19
1.13 5.23 2.56 2.49
 AICc 390 549 368 399

Est = estimate; N = number of daily milk yield observations considered to fit the model; MSE = mean squared error; RSR = root mean squared error divided by population SD; CCC = concordance correlation coefficient; Inline graphic = square root of the estimated study variance; Inline graphic = square root of the residual variance; AICc = corrected Akaike information criterion.

1

Fitted using no weighting.

2

Fitted using weighting based on the number of observations for each management practice.

3

Using weighting based on 1/SE, and all observation without the SE excluded.

4

Using weighting based on 1/SE with mean SE used for all observations with missing SE.

5

Interaction effect between improved cattle breeds and improved feeding.