Fixed effects	Significant level	Degree of freedom	Level	LSM ± SE
Milking frequency per day	***	1	3	34.71 ± 0.33
Milking frequency per day	***	1	4	36.85 ± 0.43
Lactation period	***	2	1	34.71 ± 0.33
			2	34/2 ± 0.56
			3	33.07 ± 0.69
Birth year	***	3	2003	34.71 ± 0.33
			2004	35.69 ± 0.56
			2005	36.11 ± 0.67
			2006	37.11 ± 0.82
Calving year	***	2	2007	34.71 ± 0.33
			2008	33.71 ± 0.54
			2009	34.97 ± 0.66
Age	***	3	1	34.71 ± 0.33
			2	40.81 ± 0.74
			3	32.4 ± 0.51
			4	34.02 ± 0.51
Days in milking	***	3	1	34.71 ± 0.33
			2	28.06 ± 0.53
			3	31.88 ± 0.42
			4	37.42 ± 0.42