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Genetic Improvement of Mastitis Resistance: Validation of Somatic Cell Score and Clinical Mastitis as Selection Criteria

Authors
Journal
Journal of Dairy Science
0022-0302
Publisher
American Dairy Science Association
Volume
86
Issue
12
Identifiers
DOI: 10.3168/jds.s0022-0302(03)74027-2
Keywords
  • Genetics And Breeding

Abstract

Abstract Mean daughter deviations for clinical mastitis among second-crop daughters were regressed on predicted transmitting abilities for clinical mastitis and lactation mean somatic cell score in first-crop daughters to validate the predictive ability of these traits as selection criteria for reduced incidence of clinical mastitis. A total of 321 sires had 684,897 second-crop daughters, while predicted transmitting abilities were calculated for 2159 sires, based on 495,681 records of first-crop daughters. Predictive ability, as a measure of efficiency of selection, was 23 to 43% higher for clinical mastitis than for lactation mean somatic cell score. Compared to single-trait selection, predictive ability improved 8 to 13% from utilizing information on both traits. The relative weight that should be assigned to standardized predicted transmitting abilities from univariate genetic analyses were 60 to 67% for clinical mastitis and 33 to 40% for lactation mean somatic cell score. No significant nonlinear genetic relationship between the two traits was found.

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