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Title: SHORT COMMUNICATION: GENETIC EVALUATION OF MILKING SPEED FOR BROWN SWISS DAIRY CATTLE IN THE UNITED STATES

Author
item Wiggans, George
item Thornton, Laura
item NEITZEL, R - BROWN SWISS ASSOCIATION
item GENGLER, N - GEMBLOUX AGRIC UNIV

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/28/2006
Publication Date: 2/1/2007
Citation: Wiggans, G.R., Thornton, L.L., Neitzel, R., Gengler, N. 2007. Short Communication: Genetic evaluation of milking speed for Brown Swiss dairy cattle in the United States. Journal of Dairy Science. 90(2):1021-1023.

Interpretive Summary: The Brown Swiss Association began collecting milking speed appraisals in 2004. This trait is of interest particularly for international customers. Milking speed is owner recorded on a scale of 1 to 8 (slow to fast). The estimated heritability was 0.22. Significant correlations were found between milking speed and productive live and somatic cell score indicating that it may affect profitability. Faster milking speed was associated with lower somatic cell score which was not expected, however, this effect was not significant when calculated within sire of bull. Evaluations, expressed with a mean of 100 and a standard deviation of 5, were first released in May 2006.

Technical Abstract: Genetic parameters and breeding values (EBV) were estimated for milking speed in Brown Swiss cattle. Owner-recorded milking-speed scores on a 1 to 8 scale (slow to fast) were collected by the Brown Swiss Association as part of its linear type appraisal program starting in 2004. Data were 7,366 records on 6,666 cows in 393 herds. The pedigree file included 21,458 animals born in 1985 or later. Six unknown parent groups, each including four years of birth, were defined. The model included fixed effects for herd appraisal date, parity-stage of lactation, and random effects for permanent environment, animal and error. Within three parities, four 90-day stages of lactation and an unknown stage were defined. Heritability of 0.22 and repeatability of 0.42 were estimated by Average Information REML. The residual variance was 1.13. There was little trend in EBV of cows born 1999 through 2002. Scores increased with stage of lactation for first parity cows by 0.37. There was not a clear trend in later parities. Evaluations were expressed with a mean of 100 and a standard deviation of 5. The 121 bulls with 10 or more daughters had EBV ranging from 83 to 112. These had significant correlations between evaluations for milking speed and: productive life (0.56) and somatic cell score (-0.40). The association of faster milking speed with lower somatic cell score was not expected. This correlation dropped below significance when calculated within sire of bull. The milking speed information can provide useful EBV given the moderate heritability. Evaluations were first released in May 2006.