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Genetic Evaluation of Milking Speed in Brown Swiss. Introduction. International customers interested in milking speed Slow milkers disrupt parlor flow and efficiency Fast milkers may be at increased risk for mastitis. Scoring. Subjective 1 (slow) to 8 (fast) Began in 2004
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Introduction • International customers interested in milking speed • Slow milkers disrupt parlor flow and efficiency • Fast milkers may be at increased risk for mastitis
Scoring • Subjective • 1 (slow) to 8 (fast) • Began in 2004 • Maximum age of 68 mo
Data • 7,366 records (2004 to present) • 6,666 cows • 393 herds • 21,458 ancestors born in 1985 and later • 6 unknown-parent groups including 4 birth years
Animal Model • Fixed effects • Herd-appraisal date • Parity-lactation stage • 3 parities (1, 2, 3) • 4 90-d stages, 400 d, and unknown-calving group • Random effects • Animal • Permanent environment • Residual
Variance Component Estimates • Heritability = 0.22 • Repeatability = 0.42 • Residual variance = 1.13
Investigation of SCS Correlation • Identify 60 bulls with common sires • Calculate correlation of SCS with milking speed within sire of bull • Correlation = 0.14, P = 0.276 • A few bull sires in a small-population breed could have caused the correlation of 0.40
Evaluations • Base • Set to 100 with SD of 5 • Bulls born from 1994 to 1999 with 10 daughters • 121 bulls • Range of 83 to 112
Conclusions • Faster milking speed not associated with increased SCS • First evaluation for milking speed released by USDA in May 2006
Further Research • Use scores supplied by AI organizations to explore breed differences • Use DHI-supplied times to estimate parameters with objective measurements • Extend evaluation to all breeds