Genetic Parameters for Yield Traits of Holsteins, Including Lactose and Somatic Cell Score

First lactation milk, fat, protein, and lactose yields and percentage yields were analyzed using a multiple-trait sire model including herd-year-season, sire group, and age of cow as fixed effects. Somatic cell score was fit both as a fixed effect in the model and as an additional dependent variable...

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Bibliographic Details
Published in:Journal of dairy science 1992-05, Vol.75 (5), p.1342-1348
Main Authors: Welper, R. D, Freeman, A. E
Format: Article
Language:English
Subjects:
Agriculture
Agriculture, Dairy & Animal Science
Animals
Biological and medical sciences
Breeding
Cattle - genetics
Cattle - physiology
Cell Count - veterinary
Female
Food industries
Food Science & Technology
Fundamental and applied biological sciences. Psychology
Lactation - genetics
Lactose - analysis
Life Sciences & Biomedicine
Lipids - analysis
Male
Milk - analysis
Milk - cytology
Milk - secretion
Milk and cheese industries. Ice creams
Milk Proteins - analysis
Phenotype
Science & Technology
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Summary:First lactation milk, fat, protein, and lactose yields and percentage yields were analyzed using a multiple-trait sire model including herd-year-season, sire group, and age of cow as fixed effects. Somatic cell score was fit both as a fixed effect in the model and as an additional dependent variable in two analyses with almost identical results. Variance components were estimated using REML with an expectation-maximization algorithm including sire relationships. Lactose means ranged from 4.84 to 4.97% across three dairy breeds. Data used to estimate variance components were first lactation Holstein records collected from 1986 to 1988 from 5246 daughters of 392 Al sires. Heritability estimates were .30, .29, .27, and .26 for milk, fat, protein, and lactose yields; .45, .47, and .53 for fat, protein, and lactose percentage yields; and .16 for somatic cell score. Genetic correlations of lactose percentage with milk, fat, protein, fat and protein percentages, and somatic cell score were -.30, -.16, -.21, .10, .29, and -.11, respectively, and phenotypic correlations were -.08, -.02, .01, .11, .29, and -.15.
ISSN:0022-0302
1525-3198
DOI:10.3168/jds.S0022-0302(92)77885-0