Rating the Accuracy of DHI Production Records
The USDA Animal Improvement Programs Laboratory calculates the Data Collection Rating (DCR) for DHI herds. A herd’s DCR indicates the relative accuracy of individual production records and aids the effective use of DHI records based on varying amounts of data. DCR is based on the frequency of testing, the percentage of milkings weighed and sampled, and the number of test days supervised by a DHI technician. The ratings are useful for genetic evaluations, artificial insemination organizations, and breed associations, among others.
Extension Dairy Educator
Northwest Lower Michigan
Dairy producers and agribusiness professionals who use DHI records may have noticed the addition of a value labeled “DCR Milk” on the DHI-202 Herd Summary report. DCR is an abbreviation for Data Collection Rating. DCRs are calculated by USDA Animal Improvement Programs Laboratory (AIPL) and indicate the relative accuracy of individual production records.
Development of DCRs
In the past DHI testing plans were similar for most herds. A “milk tester” (now referred to as DHI technicians) came to the farm each month to collect data about each cow. The test days were unannounced and all milkings were weighed and sampled. As the management needs of dairy producers changed, more DHI testing plans were created. Testing options now include variations in number of milkings weighed and sampled, frequency of test days (more or less than 12 per year), and level of supervision.
To effectively use DHI records based on varying amounts of data, USDA-AIPL developed data collection ratings to determine the relative emphasis to place on each production record in genetic evaluations. DCRs were implemented in 1999.
Factors Influencing DCR
DCR is based on the frequency of testing, the percentage of milkings weighed and sampled, and the number of test days supervised by a DHI technician. The “traditional” milk testing plan of monthly test days with all milkings weighed and sampled by a trained DHI technician has a DCR value of 100.
A DCR greater than 100 is possible when supervised milk weights and/or samples are collected more frequently (e.g., 5 days of data collected each month through electronic meters in the parlor). DCR values are less than 100 for supervised AM/PM testing plans where only a portion of the milkings are weighed and/or sampled at each test day. Test days that occur less frequently than monthly also would result in DCRs less than 100. Unsupervised testing plans are weighted 75% of supervised plans and receive a DCR value no greater than 75.
DCRs are calculated for individual cow production records and are based on a 305-day lactation. Separate DCRs are calculated for milk and components (fat, protein) because some testing plans may result in different amounts of data collected for milk yield compared to the components. For example, in some plans all milk weights are recorded but samples are only collected on a portion of the milkings. Individual cow records that are completed in less than 305 days or are terminated early due to culling or death will have DCRs that reflect the lesser amount of information available.
A DCR also can be calculated for the herd. It is equivalent to the DCR of a cow tested in that herd that reached 305 days in milk on the herd’s most recent test day. See table 1 for sample DCR values based on several of the more common testing plans.
Various Uses of DCR in the Dairy Industry
USDA-AIPL uses DCR values to determine the weighting that each production record should receive in the genetic evaluations. Records that incorporate more data and consequently have higher DCR values will be weighted more heavily when calculating predicted transmitting abilities for bulls and cows. Implementation of DCRs also allowed USDA-AIPL to expand its database to include production records from unsupervised DHI herds (sometimes referred to as owner-sampler).
Artificial insemination (AI) organizations want to know the DCRs for herds that participate in their progeny testing programs. A herd’s eligibility for incentive payments for production records of young sires’ daughters may be dependent on the DCR of the individual production records as well as the herd DCR. Some AI organizations have a tiered scale of incentives based on the DCR value.
Breed associations report DCR values for production records listed on pedigrees. DCR values also are used to define records that can be used in herd and cow recognition programs.
Level of accuracy of DHI production records is considered by various segments of the dairy industry in determining how to use the records. With significant variations in the type of testing plans used by DHI herds today, it is not enough to just know the type of DHI testing plan for the herd. Consequently, data collection ratings were developed to reflect the relative accuracy of the records. DCR values are used in calculating genetic evaluations, determining incentive payments for herds participating in young sire sampling programs, and recognizing outstanding herd and cow performance by breed associations.
DCR reflects milk records’ accuracy level. <http://www.dhia.org/12-07%20National%20DHIA.pdf>. Accessed August 27, 2008.
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