Jersey Jargon, March 2020


Among the herd management reports Jersey breeders receive from the American Jersey Cattle Association (AJCA) is the AJCA Quarterly Lactation Summary. This report includes production information for cows that completed a lactation during the quarter on an actual and mature equivalent (m.e.) basis. The report also includes a lactation average for these cows.

This information is then used to calculate year-end lactation averages for individual herds and for the Jersey breed. The Jersey breed’s annual production summary and top herds are published in the March issue of the Jersey Journal.

Most often, cow numbers on the AJCA Lactation Summary and those from Dairy Herd Improvement (DHI) are similar. However, there are times when the two numbers might differ. This is largely due to Herd Register (HR) status of the cow, days-in-milk (DIM) and data collection ratings (DCRs) of the records.

In this month’s Jersey Jargon, we’ll further explain why numbers for the AJCA lactation average and the DHI rolling herd average might differ.

AJCA Lactation Summary

The AJCA Lactation Summary is sent to herd owners who participate in the AJCA’s performance programs: REAP (Registration, Equity, Appraisal and Performance), TPE (Total Performance Evaluation) Plus or Basic, and Performance Records Plus or Basic.
Information for each cow includes cow control number (CNN), registration name and number, calving date, age at calving, and DIM. Performance information includes milk, fat, protein and cheese yield on an actual and m.e. basis, along with component tests for fat and protein. DCR is also shown with the record.

Though this list includes all cows in the herd, records included in the herd’s lactation average must meet certain qualifications. Cows in the lactation average must be HR or Generation Count {4}, {5} or {6}. Lactations need to be at least 180 days in length and have a DCR of 85 or higher. Records included in the average will be identified with an asterisk on the AJCA Lactation Summary.
Thus, if a dairy producer is milking a relatively large proportion of cows with registry status of GC {3} or lower, cow numbers in the herd lactation average will be smaller than the DHI report, which includes all cows regardless of AJCA registry status. As well, if cows are sold before they reach 180 DIM, they won’t be included and cow numbers will vary between AJCA and DHI, with DHI averages running slightly higher.

Keep in mind that performance information for all cows will be reported on official performance pedigrees and progeny reports, regardless of registry status, lactation length or DCR.

The AJCA Lactation Summary is an opt-in product, meaning Jersey breeders need to request to receive the report. This can be accomplished by emailing