Owner-Sampler Records

Additional edits are imposed for owner-sampler records (lactation records with OS% > 50 are considered owner-sampler). These edits include:

  1. 40% valid identification of animals in the herd and their sires and birth dates
  2. a reasonable correspondence between bulk tank measurements and the sum of all individual cow milk weights (81 <= percent milk shipped <= 117)
  3. a proportion of outliers among owner-sampler records in the herd below a threshold based on herd size

In May 2003 the basis for owner-sampler status determination was switched from the herd's DHI type-of-test code to its test-day supervision code. The number of unsupervised tests divided by the total number of tests determines owner sampler percentage (OS%) for lactation records. In August 2003 test data that were electronically collected (supervision code 6) were defined as 50% owner-sampler (contributing 0.5 to the number of unsupervised tests in determining OS%) as long as the DHI type-of-test code indicates a supervised test plan. Test-day data with supervision codes 3 and 7 (both the supervisor and owner collect data on test day), which were previously defined as 50% owner-sampler were reduced to 25% owner-sampler, recognizing that direct test-day supervision is greater for this testing arrangement. The implemented changes preserve the intent of the LER program to generate supervised records by extending some credit for the use of electronic meters for data collection between supervisor visits.

In August 2003, limits for percentage of milk shipped and percentage of animals completely identified began being applied to owner-sampler lactation records on a yearly basis. The values for the last herd test date during each calendar year are used for all calvings during that year. To prevent reporting errors from causing a year's data to be excluded, values from the previous test day must support the decision to reject data.

Owner-sampler records for calvings before July 1, 1996 are excluded from evaluations because quality certification of laboratories and meters can not be ensured for records collected previously.

Outliers are defined based on interquartile ranges. For herds with 10 or more cows calving in a year, possible outliers are more than 1.5 ranges from the herd mean (average of upper and lower quartiles) and probable outliers are more than 3 ranges from the mean. For such herds, the threshold of possible outliers per herd-year was raised from 6.4 to 10% in August, 2003. All owner-sampler records data for herds years that exceed this threshold, or with 2 or more probable outliers, are deleted. All herd years are allowed at least one possible outlier. Data for individual cows are deleted if more than 2 ranges from the herd mean. For smaller herds, the thresholds are 8000 and 14000 lbs. for herds, and 10000 lbs. for individual cows.