LIC | Reliability of Herd Testing Regimes


Reliability of Herd Testing Regimes

Reliable information from four tests every year

There are differences in the reliability of information between different testing regimes.

Testing twice in a 24-hour period is the most reliable method of herd testing. Morning testing is more reliable than afternoon testing as cows generally give a bigger volume of milk at morning milkings.

 

What do we mean by the term 'reliability'?

Reliability provides an estimate of the extent to which the PW may change when further information is obtained.

As new herd-test information is added to the evaluation, the reliability of the animals directly affected by the new information should always increase.

Top cows will still be top cows.

Within-herd rankings will not change dramatically between Classic Test (PM & AM sampling) and Single Test. In other words, top PW cows will still be ranked as top PW cows. 

 

Reliability of Production Worth Under Different Herd Testing Sampling Regimes

Reliability measures how much information has contributed to the evaluation for that animal, and indicated how confident we can be that the PW is a good indication of the animals true merit. 

This table shows the reliability of different sampling regimes for a totally unrecorded cow. Cows with good records will have higher reliabilities because they will have ancestry and progeny records contribution to their evaluation. 

Tests per year
Lactations
Classic Test PM & AM
Single Test AM
Single Test PM
1
1
38%
32%
26%
1
2
56%
49%
42%
1
3
67%
60%
53%
1
4
73%
67%
59%
2
1
47%
41%
35%
2
2
66%
59%
53%
2
3
75%
70%
63%
2
4
80%
75%
69%
3
1
51%
46%
40%
3
2
69%
64%
58%
3
3
79%
74%
68%
3
4
83%
78%
73%
4
1
53%
48%
43%
4
2
72%
67%
61%
4
3
80%
76%
70%
4
4
84%
80%
75%
5
1
55%
51%
46%
5
2
73%
69%
64%
5
3
82%
77%
73%
5
4
85%
81%
77%
6
1
56%
52%
47%
6
2
74%
70%
65%
6
3
82%
78%
74%
6
4
86%
82%
78%
7
1
57%
53%
49%
7
2
75%
71%
66%
7
3
83%
79%
75%
7
4
87%
83%
79%
8
1
58%
54%
50%
8
2
76%
72%
67%
8
3
84%
80%
76%
8
4
87%
83%
79%
9
1
59%
55%
51%
9
2
76%
72%
68%
9
3
84%
80%
76%
9
4
87%
84%
80%
10
1
59%
56%
52%
10
2
76%
73%
69%
10
3
84%
81%
77%
10
4
87%
84%
80%
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