Genetics of tolerance to heat stress in milk yield of dairy buffaloes assessed by a random regression model

Detalhes bibliográficos
Autor(a) principal: Stefani, Gabriela [UNESP]
Data de Publicação: 2020
Tipo de documento: Tese
Idioma: eng
Título da fonte: Repositório Institucional da UNESP
Texto Completo: http://hdl.handle.net/11449/202400
Resumo: Buffaloes are recognizably rustic and well adapted to adverse tropical climates. However, there are reports in the literature that these animals show signs of suffering when exposed to high temperatures and solar radiation. Despite being an important issue, the effect of heat stress on milk yield in buffaloes has never been studied in Brazil. The objectives of this study were to assess the effects of heat stress on the milk yield and investigate the presence of genotype x environment interaction (G×E) in Brazilian dairy buffaloes reared under tropical conditions. With this, 53,113 test-day (TD) records for milk yield from 3,179 first-lactations of dairy buffaloes, collected between 1987 and 2018 were evaluated. A mixed model considering days in milk (DIM) and temperature-humidity index (THI) was applied to quantify milk yield losses due to heat stress. The most detrimental effect of THI on TD milk yield was observed in the intermediate stages of lactation, after lactation peak, in DIM 105-154 and 155-204 days (-0.002 and -0.014kg/day per THI, respectively). The least squares means of TD milk yield was used to identify a heat stress threshold by a piecewise linear regression model. A substantial reduction in TD milk yield due to heat stress was observed for THI values above 76.8 (-0.26 kg/day per increase of 1 THI unit). An analysis using a single-trait random regression animal model was carried out to estimate variance components and genetic parameters for TD milk yield over THI and DIM values. The additive genetic variance and heritability estimates were higher for lower THI values and earlier DIM. Lower genetic correlations between TD records were observed between opposite extremes of THI scale (THI=60 vs THI=80), reaching zero value. The genetic trends observed for the regression coefficients related to general yield level (0.02) and specific ability to respond to heat stress (-0.006) indicated that selection to increase milk yield did not affect the specific ability to respond to heat stress until the present moment. These trends reflect the low genetic correlation between these components (0.085±0.157), and are indicative of GxE with reordering of the estimated breeding values across the environment classes. Thus, the best animals for milk yield in the comfort zone are not necessarily the best in the zone of heat stress. Therefore, actions for monitoring trends of genetic components related to response to heat stress are recommended.
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spelling Genetics of tolerance to heat stress in milk yield of dairy buffaloes assessed by a random regression modelGenética da tolerância ao estresse calórico na produção de leite de búfalas leiteiras avaliada por um modelo de regressão aleatóriaInteração genótipo-ambienteBúfalosEstresse calóricoRegressão aleatóriaÍndice de temperatura-umidadeGenotype by environment interactionBuffaloesHeat stressRandom regressionTemperature-humidity indexBuffaloes are recognizably rustic and well adapted to adverse tropical climates. However, there are reports in the literature that these animals show signs of suffering when exposed to high temperatures and solar radiation. Despite being an important issue, the effect of heat stress on milk yield in buffaloes has never been studied in Brazil. The objectives of this study were to assess the effects of heat stress on the milk yield and investigate the presence of genotype x environment interaction (G×E) in Brazilian dairy buffaloes reared under tropical conditions. With this, 53,113 test-day (TD) records for milk yield from 3,179 first-lactations of dairy buffaloes, collected between 1987 and 2018 were evaluated. A mixed model considering days in milk (DIM) and temperature-humidity index (THI) was applied to quantify milk yield losses due to heat stress. The most detrimental effect of THI on TD milk yield was observed in the intermediate stages of lactation, after lactation peak, in DIM 105-154 and 155-204 days (-0.002 and -0.014kg/day per THI, respectively). The least squares means of TD milk yield was used to identify a heat stress threshold by a piecewise linear regression model. A substantial reduction in TD milk yield due to heat stress was observed for THI values above 76.8 (-0.26 kg/day per increase of 1 THI unit). An analysis using a single-trait random regression animal model was carried out to estimate variance components and genetic parameters for TD milk yield over THI and DIM values. The additive genetic variance and heritability estimates were higher for lower THI values and earlier DIM. Lower genetic correlations between TD records were observed between opposite extremes of THI scale (THI=60 vs THI=80), reaching zero value. The genetic trends observed for the regression coefficients related to general yield level (0.02) and specific ability to respond to heat stress (-0.006) indicated that selection to increase milk yield did not affect the specific ability to respond to heat stress until the present moment. These trends reflect the low genetic correlation between these components (0.085±0.157), and are indicative of GxE with reordering of the estimated breeding values across the environment classes. Thus, the best animals for milk yield in the comfort zone are not necessarily the best in the zone of heat stress. Therefore, actions for monitoring trends of genetic components related to response to heat stress are recommended.Búfalos são animais reconhecidamente rústicos e bem adaptados à climas tropicais adversos. No entanto, há relatos na literatura de que esses animais mostram sinais de sofrimento quando expostos à elevadas temperaturas e radiação solar. Apesar de ser um assunto importante, o efeito do estresse calórico sobre a produção de leite em bubalinos nunca foi estudado no Brasil. Os objetivos deste estudo foram avaliar os efeitos do estresse calórico sobre a produção de leite e investigar a presença da interação genótipo x ambiente (G×E) em bubalinos brasileiros criados em condições tropicais. Com isso, foram avaliados registros de produção de leite de 53.113 controles leiteiros de 3.179 primeiras lactações de búfalas leiteiras, coletadas entre 1987 e 2018. Foi aplicado um modelo misto considerando dias em lactação (DIM) e índice de temperatura-umidade (THI) para quantificar as perdas na produção de leite devido ao estresse calórico. O efeito mais prejudicial do THI sobre a produção de leite no dia do controle foi observado nos estágios intermediários da lactação, após o pico da lactação, nos DIM 105-154 e 155-204 dias (-0,002 e -0,014kg/dia por THI, respectivamente). A média dos mínimos quadrados da produção de leite no dia do controle foi usada para identificar um limiar de estresse calórico por meio de um modelo de regressão linear por partes. Uma redução substancial na produção de leite no dia do controle devido ao estresse calórico foi observada para valores de THI acima de 76,8 (-0,26kg/dia por cada aumento de 1 unidade de THI). Uma análise utilizando um modelo animal unicaracterística de regressão aleatória foi realizada para estimar os componentes de variância e os parâmetros genéticos para a produção de leite no dia do controle sobre os valores de THI e DIM. A variação genética aditiva e as estimativas de herdabilidade foram maiores para valores mais baixos de THI e menores DIM. Menores correlações genéticas entre as produções de leite no dia do controle foram observadas entre os extremos opostos da escala THI (THI=60 vs THI=80), alcançando valor zero. As tendências genéticas observadas para os coeficientes de regressão relacionados ao nível de produção geral (0,02) e capacidade específica de responder ao estresse calórico (-0,006) indicaram que a seleção para aumentar a produção de leite não afetou a capacidade específica de responder ao estresse térmico até o momento presente. Essas tendências refletem a baixa correlação genética entre esses componentes (0,085±0,157), e são um indicativo de GxE com reordenamento dos valores genéticos estimados ao longo da escala ambiental. Isso significa que os melhores animais para produção de leite na zona de conforto não são necessariamente os melhores na zona de estresse calórico. Portanto, ações para monitorar tendências de componentes genéticos relacionados à resposta ao estresse calórico são recomendadas.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)88882.180636/2018-0188887.529039/2020-00Universidade Estadual Paulista (Unesp)Tonhati, Humberto [UNESP]Santana Júnior, Mário LuizEl Faro, LeniraUniversidade Estadual Paulista (Unesp)Stefani, Gabriela [UNESP]2021-01-19T21:36:26Z2021-01-19T21:36:26Z2020-12-17info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/doctoralThesisapplication/pdfhttp://hdl.handle.net/11449/20240033004102030P4enginfo:eu-repo/semantics/openAccessreponame:Repositório Institucional da UNESPinstname:Universidade Estadual Paulista (UNESP)instacron:UNESP2024-06-05T18:32:21Zoai:repositorio.unesp.br:11449/202400Repositório InstitucionalPUBhttp://repositorio.unesp.br/oai/requestopendoar:29462024-08-05T17:33:17.001335Repositório Institucional da UNESP - Universidade Estadual Paulista (UNESP)false
dc.title.none.fl_str_mv Genetics of tolerance to heat stress in milk yield of dairy buffaloes assessed by a random regression model
Genética da tolerância ao estresse calórico na produção de leite de búfalas leiteiras avaliada por um modelo de regressão aleatória
title Genetics of tolerance to heat stress in milk yield of dairy buffaloes assessed by a random regression model
spellingShingle Genetics of tolerance to heat stress in milk yield of dairy buffaloes assessed by a random regression model
Stefani, Gabriela [UNESP]
Interação genótipo-ambiente
Búfalos
Estresse calórico
Regressão aleatória
Índice de temperatura-umidade
Genotype by environment interaction
Buffaloes
Heat stress
Random regression
Temperature-humidity index
title_short Genetics of tolerance to heat stress in milk yield of dairy buffaloes assessed by a random regression model
title_full Genetics of tolerance to heat stress in milk yield of dairy buffaloes assessed by a random regression model
title_fullStr Genetics of tolerance to heat stress in milk yield of dairy buffaloes assessed by a random regression model
title_full_unstemmed Genetics of tolerance to heat stress in milk yield of dairy buffaloes assessed by a random regression model
title_sort Genetics of tolerance to heat stress in milk yield of dairy buffaloes assessed by a random regression model
author Stefani, Gabriela [UNESP]
author_facet Stefani, Gabriela [UNESP]
author_role author
dc.contributor.none.fl_str_mv Tonhati, Humberto [UNESP]
Santana Júnior, Mário Luiz
El Faro, Lenira
Universidade Estadual Paulista (Unesp)
dc.contributor.author.fl_str_mv Stefani, Gabriela [UNESP]
dc.subject.por.fl_str_mv Interação genótipo-ambiente
Búfalos
Estresse calórico
Regressão aleatória
Índice de temperatura-umidade
Genotype by environment interaction
Buffaloes
Heat stress
Random regression
Temperature-humidity index
topic Interação genótipo-ambiente
Búfalos
Estresse calórico
Regressão aleatória
Índice de temperatura-umidade
Genotype by environment interaction
Buffaloes
Heat stress
Random regression
Temperature-humidity index
description Buffaloes are recognizably rustic and well adapted to adverse tropical climates. However, there are reports in the literature that these animals show signs of suffering when exposed to high temperatures and solar radiation. Despite being an important issue, the effect of heat stress on milk yield in buffaloes has never been studied in Brazil. The objectives of this study were to assess the effects of heat stress on the milk yield and investigate the presence of genotype x environment interaction (G×E) in Brazilian dairy buffaloes reared under tropical conditions. With this, 53,113 test-day (TD) records for milk yield from 3,179 first-lactations of dairy buffaloes, collected between 1987 and 2018 were evaluated. A mixed model considering days in milk (DIM) and temperature-humidity index (THI) was applied to quantify milk yield losses due to heat stress. The most detrimental effect of THI on TD milk yield was observed in the intermediate stages of lactation, after lactation peak, in DIM 105-154 and 155-204 days (-0.002 and -0.014kg/day per THI, respectively). The least squares means of TD milk yield was used to identify a heat stress threshold by a piecewise linear regression model. A substantial reduction in TD milk yield due to heat stress was observed for THI values above 76.8 (-0.26 kg/day per increase of 1 THI unit). An analysis using a single-trait random regression animal model was carried out to estimate variance components and genetic parameters for TD milk yield over THI and DIM values. The additive genetic variance and heritability estimates were higher for lower THI values and earlier DIM. Lower genetic correlations between TD records were observed between opposite extremes of THI scale (THI=60 vs THI=80), reaching zero value. The genetic trends observed for the regression coefficients related to general yield level (0.02) and specific ability to respond to heat stress (-0.006) indicated that selection to increase milk yield did not affect the specific ability to respond to heat stress until the present moment. These trends reflect the low genetic correlation between these components (0.085±0.157), and are indicative of GxE with reordering of the estimated breeding values across the environment classes. Thus, the best animals for milk yield in the comfort zone are not necessarily the best in the zone of heat stress. Therefore, actions for monitoring trends of genetic components related to response to heat stress are recommended.
publishDate 2020
dc.date.none.fl_str_mv 2020-12-17
2021-01-19T21:36:26Z
2021-01-19T21:36:26Z
dc.type.status.fl_str_mv info:eu-repo/semantics/publishedVersion
dc.type.driver.fl_str_mv info:eu-repo/semantics/doctoralThesis
format doctoralThesis
status_str publishedVersion
dc.identifier.uri.fl_str_mv http://hdl.handle.net/11449/202400
33004102030P4
url http://hdl.handle.net/11449/202400
identifier_str_mv 33004102030P4
dc.language.iso.fl_str_mv eng
language eng
dc.rights.driver.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.publisher.none.fl_str_mv Universidade Estadual Paulista (Unesp)
publisher.none.fl_str_mv Universidade Estadual Paulista (Unesp)
dc.source.none.fl_str_mv reponame:Repositório Institucional da UNESP
instname:Universidade Estadual Paulista (UNESP)
instacron:UNESP
instname_str Universidade Estadual Paulista (UNESP)
instacron_str UNESP
institution UNESP
reponame_str Repositório Institucional da UNESP
collection Repositório Institucional da UNESP
repository.name.fl_str_mv Repositório Institucional da UNESP - Universidade Estadual Paulista (UNESP)
repository.mail.fl_str_mv
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