Effective thermal conductivity of the hair coat of Holstein cows in a tropical environment

Detalhes bibliográficos
Autor(a) principal: Maia,Alex Sandro Campos
Data de Publicação: 2009
Outros Autores: Silva,Roberto Gomes da, Souza Junior,João Batista Freire de, Silva,Rosiane Batista da, Domingos,Hérica Girlane Tertulino
Tipo de documento: Artigo
Idioma: eng
Título da fonte: Revista Brasileira de Zootecnia (Online)
Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S1516-35982009001100022
Resumo: The objective of the present study was to assess the effective thermal conductivity of the hair coat (k ef, mW.m-1.K-1) of Holstein cows in a tropical environment, as related to conduction and radiation in the absence of free convection. The average k ef was 49.72 mW.m-1.K-1, about twice the conductivity of the air (26 mW.m-1.K-1) and much less than that of the hair fibres (260 mW.m-1.K-1). The low k ef values were attributed mainly to the small cross area of individual hairs, ρef/ρf (17.2% and 21.3% for black and white hairs, respectively). White coats were denser, with longer hairs and significantly higher k ef (53.15 mW.m-1.K-1) than that of the black hairs (49.25 mW.m-1.K-1). The heritability coefficient of the effective thermal conductivity was calculated as h²=0.18 the possibility was discussed of selecting cattle for increased heat transfer through the hair coat.
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spelling Effective thermal conductivity of the hair coat of Holstein cows in a tropical environmenthair coatHolstein cowsthermal conductivityThe objective of the present study was to assess the effective thermal conductivity of the hair coat (k ef, mW.m-1.K-1) of Holstein cows in a tropical environment, as related to conduction and radiation in the absence of free convection. The average k ef was 49.72 mW.m-1.K-1, about twice the conductivity of the air (26 mW.m-1.K-1) and much less than that of the hair fibres (260 mW.m-1.K-1). The low k ef values were attributed mainly to the small cross area of individual hairs, ρef/ρf (17.2% and 21.3% for black and white hairs, respectively). White coats were denser, with longer hairs and significantly higher k ef (53.15 mW.m-1.K-1) than that of the black hairs (49.25 mW.m-1.K-1). The heritability coefficient of the effective thermal conductivity was calculated as h²=0.18 the possibility was discussed of selecting cattle for increased heat transfer through the hair coat.Sociedade Brasileira de Zootecnia2009-11-01info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersiontext/htmlhttp://old.scielo.br/scielo.php?script=sci_arttext&pid=S1516-35982009001100022Revista Brasileira de Zootecnia v.38 n.11 2009reponame:Revista Brasileira de Zootecnia (Online)instname:Sociedade Brasileira de Zootecnia (SBZ)instacron:SBZ10.1590/S1516-35982009001100022info:eu-repo/semantics/openAccessMaia,Alex Sandro CamposSilva,Roberto Gomes daSouza Junior,João Batista Freire deSilva,Rosiane Batista daDomingos,Hérica Girlane Tertulinoeng2010-01-05T00:00:00Zoai:scielo:S1516-35982009001100022Revistahttps://www.rbz.org.br/pt-br/https://old.scielo.br/oai/scielo-oai.php||bz@sbz.org.br|| secretariarbz@sbz.org.br1806-92901516-3598opendoar:2010-01-05T00:00Revista Brasileira de Zootecnia (Online) - Sociedade Brasileira de Zootecnia (SBZ)false
dc.title.none.fl_str_mv Effective thermal conductivity of the hair coat of Holstein cows in a tropical environment
title Effective thermal conductivity of the hair coat of Holstein cows in a tropical environment
spellingShingle Effective thermal conductivity of the hair coat of Holstein cows in a tropical environment
Maia,Alex Sandro Campos
hair coat
Holstein cows
thermal conductivity
title_short Effective thermal conductivity of the hair coat of Holstein cows in a tropical environment
title_full Effective thermal conductivity of the hair coat of Holstein cows in a tropical environment
title_fullStr Effective thermal conductivity of the hair coat of Holstein cows in a tropical environment
title_full_unstemmed Effective thermal conductivity of the hair coat of Holstein cows in a tropical environment
title_sort Effective thermal conductivity of the hair coat of Holstein cows in a tropical environment
author Maia,Alex Sandro Campos
author_facet Maia,Alex Sandro Campos
Silva,Roberto Gomes da
Souza Junior,João Batista Freire de
Silva,Rosiane Batista da
Domingos,Hérica Girlane Tertulino
author_role author
author2 Silva,Roberto Gomes da
Souza Junior,João Batista Freire de
Silva,Rosiane Batista da
Domingos,Hérica Girlane Tertulino
author2_role author
author
author
author
dc.contributor.author.fl_str_mv Maia,Alex Sandro Campos
Silva,Roberto Gomes da
Souza Junior,João Batista Freire de
Silva,Rosiane Batista da
Domingos,Hérica Girlane Tertulino
dc.subject.por.fl_str_mv hair coat
Holstein cows
thermal conductivity
topic hair coat
Holstein cows
thermal conductivity
description The objective of the present study was to assess the effective thermal conductivity of the hair coat (k ef, mW.m-1.K-1) of Holstein cows in a tropical environment, as related to conduction and radiation in the absence of free convection. The average k ef was 49.72 mW.m-1.K-1, about twice the conductivity of the air (26 mW.m-1.K-1) and much less than that of the hair fibres (260 mW.m-1.K-1). The low k ef values were attributed mainly to the small cross area of individual hairs, ρef/ρf (17.2% and 21.3% for black and white hairs, respectively). White coats were denser, with longer hairs and significantly higher k ef (53.15 mW.m-1.K-1) than that of the black hairs (49.25 mW.m-1.K-1). The heritability coefficient of the effective thermal conductivity was calculated as h²=0.18 the possibility was discussed of selecting cattle for increased heat transfer through the hair coat.
publishDate 2009
dc.date.none.fl_str_mv 2009-11-01
dc.type.driver.fl_str_mv info:eu-repo/semantics/article
dc.type.status.fl_str_mv info:eu-repo/semantics/publishedVersion
format article
status_str publishedVersion
dc.identifier.uri.fl_str_mv http://old.scielo.br/scielo.php?script=sci_arttext&pid=S1516-35982009001100022
url http://old.scielo.br/scielo.php?script=sci_arttext&pid=S1516-35982009001100022
dc.language.iso.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv 10.1590/S1516-35982009001100022
dc.rights.driver.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv text/html
dc.publisher.none.fl_str_mv Sociedade Brasileira de Zootecnia
publisher.none.fl_str_mv Sociedade Brasileira de Zootecnia
dc.source.none.fl_str_mv Revista Brasileira de Zootecnia v.38 n.11 2009
reponame:Revista Brasileira de Zootecnia (Online)
instname:Sociedade Brasileira de Zootecnia (SBZ)
instacron:SBZ
instname_str Sociedade Brasileira de Zootecnia (SBZ)
instacron_str SBZ
institution SBZ
reponame_str Revista Brasileira de Zootecnia (Online)
collection Revista Brasileira de Zootecnia (Online)
repository.name.fl_str_mv Revista Brasileira de Zootecnia (Online) - Sociedade Brasileira de Zootecnia (SBZ)
repository.mail.fl_str_mv ||bz@sbz.org.br|| secretariarbz@sbz.org.br
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