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Use of multivariate factor analysis to define new indicator variables for milk composition and coagulation properties in Brown Swiss cows

Macciotta, Nicolò Pietro Paolo and Cecchinato, Alessio and Mele, Marcello and Bittante, Giovanni (2012) Use of multivariate factor analysis to define new indicator variables for milk composition and coagulation properties in Brown Swiss cows. Journal of Dairy Science, Vol. 95 (12), p. 7346-7354. ISSN 0022-0302. Article.

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DOI: 10.3168/jds.2012-5546

Abstract

The aim of this study was to elucidate the structure of relationships between milk yield, composition, and coagulation properties of Brown Swiss cattle. Multivariate factor analysis was used to derive new synthetic variables that can be used for selection purposes. For this reason, genetic parameters of these new variables were estimated. Individual records on milk yield, fat and protein percentages, casein content, lactose percentage, somatic cell count, titratable acidity, and pH were taken on 1,200 Italian Brown Swiss cows located in 38 herds. Factor analysis was able to extract 4 latent variables with an associated communality equal to 70% of the total original variance. The 4 latent factors were interpreted as indicators of milk composition, coagulation, acidity, and mammary gland health, respectively. Factor scores calculated for each animal exhibited coherent patterns along the lactation and across different parities. Estimation of genetic parameters of factor scores carried out with a multiple-trait Bayesian hierarchical model showed moderate to low heritabilities (raging from 0.10 to 0.23) and genetic correlations (from −0.15 to 0.46). Results of the present study support the hypothesis of a simpler structure that controls, at least in part, the covariance of milk composition and coagulation properties. Moreover, extracted variables may be useful for both breeding and management purposes, being able to represent, with a single value for each animal, complex traits such as milk coagulation properties or health status of the mammary gland.

Item Type:Article
ID Code:8464
Status:Published
Refereed:Yes
Uncontrolled Keywords:Milk coagulation property, milk composition, factor analysis
Subjects:Area 07 - Scienze agrarie e veterinarie > AGR/17 Zootecnica generale e miglioramento genetico
Divisions:001 Università di Sassari > 01-a Nuovi Dipartimenti dal 2012 > Agraria
Publisher:American Dairy Science Association
ISSN:0022-0302
Deposited On:12 Dec 2012 13:11

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