Data Collection Rating

By Paul VanRaden
USDA-ARS-AIPL

Definitions

The accuracy of lactation records from a wide variety of test plans can be compared using a "data collection rating" (DCR). To ensure that DCR's are defined similarly across the U.S. dairy industry, standard terminology, example values, and computer programs have been provided to breed associations, dairy records processing centers, AI companies, and others. Since February 1999, DCR's are computed from test-day data at AIPL using "best prediction."

DCR: Squared correlation of estimated and true yields multiplied by a factor of 104 to give monthly testing a rating of 100 and daily testing a rating of 104.
DCRM: DCR for milk yield.
DCRC: DCR for component yields calculated as the average of fat and protein DCR.
Herd DCR: DCR of a herd; equivalent to the DCR for a cow tested in that herd that reached 305 days in milk on the herd's most recent test day.
Weight: Ratio of the error variance from daily testing to the error variance from less complete testing; computed from the DCR and used to weight lactation records in the animal model. Differs from the squared correlation and DCR because genetic and permanent environmental effects are excluded from the variance ratio.

 

Table 1. Data collection ratings (DCR's), squared correlations of true with estimated milk yields, and lactation weights for various 305-day records.
Test
plan

Test
days

Lactation
weight

 Squared
correlation

DCR

(no.)
(%)
Daily 305 100 100 104
Labor efficient record
10-d mean 1001 99 100 104
5-d mean 502 98 99 103
Monthly supervised
all milkings3 10 95 96 100
2 of 3 milkings 10 92 93 97
1 of 2 milkings 10 89 91 95
1 of 3 milkings 10 83 87 90
Monthly owner-sampler
all milkings3 10 66 72 75
2 of 3 milkings 10 64 70 73
1 of 2 milkings 10 63 69 72
1 of 3 milkings 10 60 66 69
Bimonthly supervised
all milkings3 5 90 91 95
2 of 3 milkings 5 84 87 90
1 of 2 milkings 5 79 83 86
1 of 3 milkings 5 71 75 78
Bimonthly owner-sampler
all milkings3 5 63 69 72
2 of 3 milkings 5 61 66 69
1 of 2 milkings 5 58 64 67
1 of 3 milkings 5 53 60 62
1A 10-day average reported in each of 10 mo.
2A 5-day average reported in each of 10 mo.
3Milk weights were obtained from all milkings on each test day.

 

Table 2. Data collection ratings (DCR's) for records of < 305 days with supervised monthly testing.

First-lactation DCR

 Later-lactation DCR

Test

Days in milk

 All1 a.m.-p.m.2 All a.m.-p.m.

1

 15

36

27

 23 18
2 45 49 42 39 33
3 75 61 53 54 47
4 105 71 63 67 60
5 135 80 72 78 70
6 165 87 80 86 79
7 195 92 86 92 85
8 225 96 90 96 90
9 255 99 93 99 93
10 285 100 95 100 94
1 Milk weights were obtained from all milkings on each test day.
2 Only one of the two milkings was weighed on each test day.