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Registro Completo |
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Biblioteca(s): |
Embrapa Pecuária Sul. |
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Data corrente: |
28/11/2011 |
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Data da última atualização: |
15/02/2012 |
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Tipo da produção científica: |
Resumo em Anais de Congresso |
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Autoria: |
LACA, E. A.; GENRO, T. C. M.; GENRO NETO, J. S. |
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Afiliação: |
EMILIO ANDRÉS LACA, University of California Davis, CA, USA; TERESA CRISTINA MORAES GENRO, CPPSUL; JAIRO SILVEIRA GENRO NETO, Universidade Federal de Santa Maria, RS, Brasil. |
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Título: |
Bayesian hierarchical models to improve estimation of diet composition by alkane profiles. |
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Ano de publicação: |
2011 |
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Fonte/Imprenta: |
In: REUNIÓN DE LA ASOCIACIÓN LATINOAMERICANA DE PRODUCCIÓN ANIMAL, 22., 2011, Montevideo, Uruguay. Memorias... Montevideo: Asociación Uruguaya de Producción Animal, 2011. |
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Descrição Física: |
1 CD-ROM. |
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Idioma: |
Inglês |
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Conteúdo: |
Alkane profiles in forage and feces are used to determine diet composition, essentially by inverting a linear mixing equation. Depending on the number of dietary components, number of alkanes and difference in forage profiles, the linear equations can be over or underdetermined. We compared the typical non-negative least squares (NNLS) method against a novel Bayesian hierarchical model (BHM) where diet composition is represented as latent variables modeled with parameters shared by the models for fecal and forage profiles. Forage and fecal profiles were obtained from steers grazing either Brachiaria brizantha cv Marandu, Panicum maximum cv. Mombaça, or Pennisetum purpureum cv. Cameroon at Embrapa Beef Cattle, Campo Grande, MS, Brazil. Herbage and fecal samples were collected in the dry and early wet seasons. Herbage was sampled by 20-cm horizons sorted into stem/sheath and leaf blade as dietary components. Feces were collected from 6 animals in the morning and afternoon. Fecal profiles were corrected by faecal recoveries using mean values from the literature. Distributions of diets estimated by NNLS were obtained by Monte Carlo simulation of profiles using parameters and covariance matrices estimated from data. The BHM yielded posterior distributions directly by using Monte Carlo Markov Chains. NNLS resulted in highly variables diets with distributions that were clearly non-normal. BHM resulted in quasi-normal posterior distributions. We conclude that both approaches are better than the normal approach where diet covariances are calculated ad-hoc. The BHM method has the potential to be vastly superior because it allows the simultaneous integration in a formally correct manner, however, convergence can be difficult. MenosAlkane profiles in forage and feces are used to determine diet composition, essentially by inverting a linear mixing equation. Depending on the number of dietary components, number of alkanes and difference in forage profiles, the linear equations can be over or underdetermined. We compared the typical non-negative least squares (NNLS) method against a novel Bayesian hierarchical model (BHM) where diet composition is represented as latent variables modeled with parameters shared by the models for fecal and forage profiles. Forage and fecal profiles were obtained from steers grazing either Brachiaria brizantha cv Marandu, Panicum maximum cv. Mombaça, or Pennisetum purpureum cv. Cameroon at Embrapa Beef Cattle, Campo Grande, MS, Brazil. Herbage and fecal samples were collected in the dry and early wet seasons. Herbage was sampled by 20-cm horizons sorted into stem/sheath and leaf blade as dietary components. Feces were collected from 6 animals in the morning and afternoon. Fecal profiles were corrected by faecal recoveries using mean values from the literature. Distributions of diets estimated by NNLS were obtained by Monte Carlo simulation of profiles using parameters and covariance matrices estimated from data. The BHM yielded posterior distributions directly by using Monte Carlo Markov Chains. NNLS resulted in highly variables diets with distributions that were clearly non-normal. BHM resulted in quasi-normal posterior distributions. We conclude that both approaches are bet... Mostrar Tudo |
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Palavras-Chave: |
Melhoramento forrageira; Modelo bayesiano; Perfil alcalino. |
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Categoria do assunto: |
K Ciência Florestal e Produtos de Origem Vegetal |
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URL: |
https://ainfo.cnptia.embrapa.br/digital/bitstream/item/48108/1/G158-pagina173poster.pdf
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Marc: |
LEADER 02430nam a2200181 a 4500
001 1907473
005 2012-02-15
008 2011 bl uuuu u00u1 u #d
100 1 $aLACA, E. A.
245 $aBayesian hierarchical models to improve estimation of diet composition by alkane profiles.$h[electronic resource]
260 $aIn: REUNIÓN DE LA ASOCIACIÓN LATINOAMERICANA DE PRODUCCIÓN ANIMAL, 22., 2011, Montevideo, Uruguay. Memorias... Montevideo: Asociación Uruguaya de Producción Animal$c2011
300 $c1 CD-ROM.
520 $aAlkane profiles in forage and feces are used to determine diet composition, essentially by inverting a linear mixing equation. Depending on the number of dietary components, number of alkanes and difference in forage profiles, the linear equations can be over or underdetermined. We compared the typical non-negative least squares (NNLS) method against a novel Bayesian hierarchical model (BHM) where diet composition is represented as latent variables modeled with parameters shared by the models for fecal and forage profiles. Forage and fecal profiles were obtained from steers grazing either Brachiaria brizantha cv Marandu, Panicum maximum cv. Mombaça, or Pennisetum purpureum cv. Cameroon at Embrapa Beef Cattle, Campo Grande, MS, Brazil. Herbage and fecal samples were collected in the dry and early wet seasons. Herbage was sampled by 20-cm horizons sorted into stem/sheath and leaf blade as dietary components. Feces were collected from 6 animals in the morning and afternoon. Fecal profiles were corrected by faecal recoveries using mean values from the literature. Distributions of diets estimated by NNLS were obtained by Monte Carlo simulation of profiles using parameters and covariance matrices estimated from data. The BHM yielded posterior distributions directly by using Monte Carlo Markov Chains. NNLS resulted in highly variables diets with distributions that were clearly non-normal. BHM resulted in quasi-normal posterior distributions. We conclude that both approaches are better than the normal approach where diet covariances are calculated ad-hoc. The BHM method has the potential to be vastly superior because it allows the simultaneous integration in a formally correct manner, however, convergence can be difficult.
653 $aMelhoramento forrageira
653 $aModelo bayesiano
653 $aPerfil alcalino
700 1 $aGENRO, T. C. M.
700 1 $aGENRO NETO, J. S.
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Registro original: |
Embrapa Pecuária Sul (CPPSUL) |
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| Registros recuperados : 210 | |
| 29. |  | TRINDADE, J. K. da; BONNET, O.; WALLAU, M.; GENRO, T. C. M. Consumo de forragem. In: CARVALHO, P. C. de F.; WALLAU, M. O.; BREMM, C.; BONNET, O.; TRINDADE, J. K. da; ROSA, F. Q. da; FREITAS, T. S. de; MOOJEN, F. G. (Ed.). Nativão: 30 anos de pesquisa em campo nativo. Porto Alegre: UFRGS, 2017. p. 39-41. (Boletim técnico). Publicação original digital também impressa em 2019 ISBN 978-85-66967-68-5.| Tipo: Capítulo em Livro Técnico-Científico |
| Biblioteca(s): Embrapa Pecuária Sul. |
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| 34. | | MENEGAZZI, G.; FAST, O.; CHILIBROSTE, P.; GILES, P. Y.; GENRO, T. C. M.; MATTIAUDA, D. A. Defoliation intensity impacts on feeding station exploration by dairy cows. Animal: science proceedings, v. 14, n. 4, p. 649-650, 2023.| Tipo: Resumo em Anais de Congresso |
| Biblioteca(s): Embrapa Pecuária Sul. |
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| 37. | | GENRO, T. C. M.; BREMM, C.; TRINDADE, J. K. da; VARELLA, A. C.; SOCA, P. Daily faecal excretion of alkane C32 in beef cattle females grazing natural grasslands in southern Brazil and in Uruguay. In: INTERNATIONAL GRASSLAND CONGRESS, 22., 2013, Sidney. Revitalising grasslands to sustain our communities: proceedings. New South Wales: MCI Australia, 2013. p. 698-699. Editors David L. Michalk, Geoffrey D. Millar, Warwick B. Badgery, Kim M. Broadfoot.| Tipo: Artigo em Anais de Congresso |
| Biblioteca(s): Embrapa Pecuária Sul. |
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| 39. | | TRINDADE, J. K. da; BONNET, O.; DAVID, D. B. de; WALLAU, D.; GENRO, T. C. M. Comportamento ingestivo e seleção de dietas. In: CARVALHO, P. C. de F.; WALLAU, M. O.; BREMM, C.; BONNET, O.; TRINDADE, J. K. da; ROSA, F. Q. da; FREITAS, T. S. de; MOOJEN, F. G. (Ed.). Nativão: 30 anos de pesquisa em campo nativo. Porto Alegre: UFRGS, 2017. p. 42-46.| Tipo: Capítulo em Livro Técnico-Científico |
| Biblioteca(s): Embrapa Pecuária Sul. |
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| Registros recuperados : 210 | |
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| Nenhum registro encontrado para a expressão de busca informada. |
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