TY - JOUR
T1 - Genetic Variation in Lactation Means of Somatic Cell Scores for Six Breeds of Dairy Cattle
AU - Schutz, M. M.
AU - VanRaden, P. M.
AU - Wiggans, G. R.
PY - 1994
Y1 - 1994
N2 - Lactation means of somatic cell scores from sample days were used to estimate the components of variation for additive genetic, permanent environmental, and herd-sire interaction effects. Data included records of 4314 Ayrshire, 7845 Brown Swiss, 18,115 Guernsey, 1,135,752 Holstein, 67,862 Jersey, and 787 Milking Shorthorn cows from across the US. Records were preadjusted for length of lactation. Fixed effects of herd-year, calving age, and calving month were included in animal models for estimation of variance components. Additive genetic estimates from REML relative to a phenotypic variance of 1.00 were .07 for Ayrshires, .07 for Brown Swiss, .11 for Guernseys, .09 for Holsteins, .09 for Jerseys, and .08 for Milking Shorthorns; permanent environmental estimates were .25, .26, .22, .21, .20, and .35; and herd-sire interaction estimates were .04, .02, .00, .02, .02, and .01. Effects of calving age were similar for all regions of the US but differed for Jerseys and Holsteins. Effects of calving month were similar for all breeds. Cows calving during summer had the highest lactation means for somatic cell score from sample days. Impact of calving month was greatest in the Southeast.
AB - Lactation means of somatic cell scores from sample days were used to estimate the components of variation for additive genetic, permanent environmental, and herd-sire interaction effects. Data included records of 4314 Ayrshire, 7845 Brown Swiss, 18,115 Guernsey, 1,135,752 Holstein, 67,862 Jersey, and 787 Milking Shorthorn cows from across the US. Records were preadjusted for length of lactation. Fixed effects of herd-year, calving age, and calving month were included in animal models for estimation of variance components. Additive genetic estimates from REML relative to a phenotypic variance of 1.00 were .07 for Ayrshires, .07 for Brown Swiss, .11 for Guernseys, .09 for Holsteins, .09 for Jerseys, and .08 for Milking Shorthorns; permanent environmental estimates were .25, .26, .22, .21, .20, and .35; and herd-sire interaction estimates were .04, .02, .00, .02, .02, and .01. Effects of calving age were similar for all regions of the US but differed for Jerseys and Holsteins. Effects of calving month were similar for all breeds. Cows calving during summer had the highest lactation means for somatic cell score from sample days. Impact of calving month was greatest in the Southeast.
KW - LSCS
KW - SCS
KW - arithmetic mean of sample day, Iog-transfonned SCC for a lactation
KW - breed
KW - breed
KW - mastitis
KW - sample day, Iog-transformed SCC
KW - somatic cell
KW - variance component
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U2 - 10.3168/jds.S0022-0302(94)76953-8
DO - 10.3168/jds.S0022-0302(94)76953-8
M3 - Article
C2 - 8120197
AN - SCOPUS:0028022456
VL - 77
SP - 284
EP - 293
JO - Journal of Dairy Science
JF - Journal of Dairy Science
SN - 0022-0302
IS - 1
ER -