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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 #412731

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: Genetic and genomic evaluations of milking speed and duration from automated milk recording

item Miles, Asha
item Hutchison, Jana
item Toghiani, Sajjad
item O'CONNELL, JEFFREY - University Of Maryland School Of Medicine
item FOURDRAINE, ROBERT - Dairy Records Management Systems(DRMS)
item Vanraden, Paul

Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: 3/12/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Many milking systems now record the milk produced and the duration (DUR) of each milking of every cow. Records from 131 herds and 9 different equipment manufacturers (OEM) were retrieved from on-farm databases since 2022 by Dairy Records Management Systems. Individual milk weights and durations were averaged within 23,201 complete lactations of 23,180 cows, including 9,208 first parity cows and 4,246 genotyped cows. Milking speed (MSPD) was defined as average milk divided by average DUR. Breed, milking frequency, lactation number, and OEM had substantial effects on MSPD and were included in the genetic model along with genetic groups and permanent environment. The pedigree relationship matrix included 219,703 animals with records or descendants with records plus 96 million other animals. Variances were estimated by both Gibbs sampling and REML; estimates were very similar. Residual variance for MSPD was 51% higher when only test days instead of all days were averaged. Heritability was 28% with only test days vs. 37% with all days averaged; genetic correlation was 0.97. MSPD was less stable in first parity compared to other parities. Genetic correlation of first with all lactations was 0.92 suggesting they are measuring the same trait. Milking speed had a small favorable genetic correlation with milk yield but unfavorable with somatic cell score based on 756 Holstein bulls with reliability (REL) for MSPD > 50%. Heritability for DUR was higher at 44% across all parities and 48% in first parity. Genetic correlation of DUR with MSPD was -.81 and phenotypic correlation was -.52. Largest marker effects for DUR were on chromosome 29 near 41 Mb on ARS-UCD1 map. Economic value is small for parlor milking but larger for robotic systems. Genomic predictions for MSPD for young animals born in the last 10 years averaged 37% REL compared to about 70% REL for several other traits or 27% REL for genomic predictions of residual feed intake. Much larger datasets for MSPD may be available in the future.