Table 5 Additive genetic (σ ² _a ), animal permanent environmental (σ ² _pe ), residual (σ ² _e ) variances and heritability (h²) of the test-day records of milk yield (Kg) for some selected days in milk and different milking frequency

  σ ² _a

5.0

5.7

4.9

5.2

6.1

8.1

9.1

8.0

8.5

21.7

  σ ² _pe

9.2

11.0

11.7

11.3

11.9

13.4

15.2

17.8

20.0

18.1

  σ ² _e

11.4

10.0

9.1

8.5

9.4

8.5

8.9

9.2

7.5

7.7

  h ²

0.20

0.21

0.19

0.21

0.22

0.27

0.27

0.23

0.24

0.46

  σ ² _a

4.0

4.1

6.3

6.8

7.3

9.9

14.0

16.4

14.7

12.3

  σ ² _pe

25.5

21.7

22.3

24.2

25.6

25.7

25.1

25.4

29.3

40.9

  σ ² _e

20.9

19.0

15.7

14.3

13.4

12.7

12.5

11.5

11.2

10.1

  h ²

0.08

0.09

0.14

0.15

0.16

0.20

0.27

0.31

0.27

0.19

  σ ² _a

10.1

8.9

12.0

11.6

11.5

11.2

11.0

9.5

9.1

13.5

  σ ² _pe

20.3

14.3

11.6

10.7

10.6

10.9

11.4

12.7

15.6

21.6

  σ ² _e

8.9

9.5

8.6

8.3

8.5

7.3

7.8

6.0

6.5

6.0

  h ²

0.26

0.27

0.37

0.38

0.38

0.38

0.36

0.34

0.29

0.33

  σ ² _a

16.6

12.0

10.4

10.0

8.7

10.2

14.4

16.6

19.2

15.5

  σ ² _pe

18.5

25.0

27.2

26.9

26.1

25.8

25.8

25.9

27.6

37.2

  σ ² _e

21.6

16.4

15.2

11.6

12.3

11.4

8.9

8.0

7.9

6.7

  h ²

0.29

0.23

0.20

0.21

0.18

0.22

0.29

0.33

0.35

0.26