Table 1.

Description of the data set used in the study

Lactation stage	Days in milk	Number of animals with records	Number of records	Protein yield (kg) Mean	Protein yield (kg) SD
1	5–30	99,151	99,151	0.822	0.221
2	31–55	98,320	98,320	0.885	0.227
3	56–80	98,312	98,312	0.905	0.226
4	81–105	99,209	99,209	0.912	0.227
5	106–130	97,932	97,932	0.910	0.227
6	131–155	96,976	96,976	0.902	0.228
7	156–180	96,334	96,334	0.892	0.228
8	181–205	94,948	94,948	0.878	0.226
9	206–230	93,299	93,299	0.861	0.226
10	231–255	90,981	90,981	0.841	0.224
11	256–280	81,472	81,472	0.819	0.224
12	281–305	65,148	65,148	0.806	0.227
Total	5–305	167,269	1,112,082	0.872	0.229