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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Animal Genomics and Improvement Laboratory » Research » Publications at this Location » Publication #402257
Research Project: Increasing Accuracy of Genomic Prediction, Developing Algorithms, Selecting Markers, and Evaluating New Traits to Improve Dairy Cattle

Location: Animal Genomics and Improvement Laboratory

Title: Combined effects of milking intervals and frequencies

Author
item Vanraden, Paul
item Miles, Asha
item WU, X - Council On Dairy Cattle Breeding
item NOORDHOFF, D - Retired Non ARS Employee

Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: 3/21/2023
Publication Date: 6/25/2023
Citation: Van Raden, P.M., Miles, A.M., Wu, X.L., Noordhoff, D.R. 2023. Combined effects of milking intervals and frequencies [abstract]. Journal of Dairy Science. 106(Suppl. 1):190(abstr. 2717).

Interpretive Summary:

Technical Abstract: Dairy herd income depends on actual production, whereas the merit of individual cows can be better compared using standardized performance. Adjustment factors for milking interval estimate actual 24-hour yield from morning or evening data (AM-PM records) but have not standardized to the higher yield the cow would have produced if milked at even intervals of 12 and 12 hours. By contrast, daily yields with three milkings (3X) are standardized downward to the expected twice daily (2X) yield. Smooth, nonlinear functions can standardize for both number of milkings and milking intervals to account for increases in yield from 2X to 3X, 4X, etc., decreases from 1X milking, and decreases from uneven milking intervals. Both adjustments can be computed using a constant c to the power of -N for cows with N equally spaced milkings per day as NX factor = (1 – c^-N) / (1 – c^-2). Division by 1 – c^-2 simply sets the 2X factor to 1.0 for the standard milking frequency of 2. Constant c is obtained using numerical methods from a known 3X factor such as 1.11, which gives c = 2.5. Interval and frequency factors use i milking intervals as fractions of the 24-hour day as weights (w_i = interval / 24) and equivalent milking frequencies (N_i = 24 / interval) that are not necessarily integers. Combined factors are then summation w_i * N_i. For adjusting and reporting multi-day average yields, the combined factors are summed across days and then divided by the number of days (or partial days). The proposed function fitted well to actual data from 7,544 Holstein cows with differing milking intervals and could help when comparing cows within or across herds. For example, 3X takes 50% more milking labor than 2X and gives 9-14% more yield and components. A parlor milking 24 hours and 3X / day would expect 11% less milk if dropping to 2X with 12-hour intervals and would expect a further loss of 4% with 8- and 16-hour intervals by moving the morning and evening shifts closer. Standardizing records for differing intervals can more fairly compare cows in herds milking groups of cows with differing intervals or with robots, provide helpful management advice, and improve genetic evaluation.