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 | Acesso ao texto completo restrito à biblioteca da Embrapa Caprinos e Ovinos. Para informações adicionais entre em contato com cnpc.biblioteca@embrapa.br. |
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Registro Completo |
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Biblioteca(s): |
Embrapa Caprinos e Ovinos. |
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Data corrente: |
01/08/1992 |
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Data da última atualização: |
19/07/2023 |
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Autoria: |
BLAXTER, K. L.; MITCHELL, H. H. |
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Título: |
The factorization of the protein requirements of ruminants and of the protein values of feeds, with particular reference to the significance of the metabolic fecal nitrogen. |
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Ano de publicação: |
1948 |
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Fonte/Imprenta: |
Journal of Animal Science, v. 7, v. 3, p. 351-372, Aug. 1948. |
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DOI: |
https://doi.org/10.2527/jas1948.73351x |
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Idioma: |
Inglês |
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Conteúdo: |
Abstract: The factorial method for the estimation of the protein requirements of animals is briefly outlined, and the divergence between such estimates for cattle and sheep and accepted feeding standards is discussed. The metabolic fecal N which can be regarded as an inevitable loss to the body has been incorporated as a term in the general factorial procedure, and it is shown that the requirement of the animal for digestible protein cannot be divorced from the character of the ration which is fed, because the latter determines the output of metabolic fecal nitrogen. The term ?available protein,? represented by the equation is suggested, to obviate the difficulties of multiple ration standards implied under a above. Available protein represents the metabolizable protein of a feed, taxed for the loss of body N which its ingestion entails and thus available for covering endogenous losses and the demands of other anabolic processes. A method of calculation of the true digestibility coefficients of feeds and classes of feeds is presented, and it is shown that the same equation may be used to predict accurately the metabolic fecal N. A table of feed composition, illustrating the computation of metabolizable, apparently digestible, and available protein is given, based on the above methods. The importance of the metabolic fecal N in determining the minimum requirement of protein of the ruminant is shown by the explanation thus afforded of the anomalous results obtained when rations high in fiber are fed to cattle. Two examples of the factorization procedure are given: for growing and fattening ewe lambs and for Holstein heifers. In both cases the effect of high quality and poor quality rations (as judged by the ratio of TDN to DM they contain) is illustrated. It is shown that the metabolic fecal loss of N may account for some 20?70 percent of the requirement of the ruminant for metabolizable protein, depending on age of the animal. The effect of this factor on the protein requirement of monogastric animals is briefly discussed. The metabolic fecal loss of N, entailing its replacement by truly digestible N, accounts for a part of the discrepancy between practical feeding standards and the factorized requirement. Nevertheless, it appears that current standards still tend to underfeed young animals and to overfeed more mature animals as far as their protein requirements are concerned. The metabolic fecal energy is presumably in the same category with reference to energy requirements of animals as the metabolic fecal nitrogen with reference to protein requirements. But before net energy requirements, or the net (or metabolizable) energy value of feeds can be corrected, information must be obtained on the magnitude of the metabolic fecal energy and its determining factors. MenosAbstract: The factorial method for the estimation of the protein requirements of animals is briefly outlined, and the divergence between such estimates for cattle and sheep and accepted feeding standards is discussed. The metabolic fecal N which can be regarded as an inevitable loss to the body has been incorporated as a term in the general factorial procedure, and it is shown that the requirement of the animal for digestible protein cannot be divorced from the character of the ration which is fed, because the latter determines the output of metabolic fecal nitrogen. The term ?available protein,? represented by the equation is suggested, to obviate the difficulties of multiple ration standards implied under a above. Available protein represents the metabolizable protein of a feed, taxed for the loss of body N which its ingestion entails and thus available for covering endogenous losses and the demands of other anabolic processes. A method of calculation of the true digestibility coefficients of feeds and classes of feeds is presented, and it is shown that the same equation may be used to predict accurately the metabolic fecal N. A table of feed composition, illustrating the computation of metabolizable, apparently digestible, and available protein is given, based on the above methods. The importance of the metabolic fecal N in determining the minimum requirement of protein of the ruminant is shown by the explanation thus afforded of the anomalous results obtained when ration... Mostrar Tudo |
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Palavras-Chave: |
Fattening; Metodo fatorial; Requerimento proteico. |
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Thesagro: |
Nutrição; Ruminante. |
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Thesaurus Nal: |
Animal production; Cattle feeding; Feeds; Finishing; Heifers; Lambs; Nutrient requirements; Protein requirement; Ruminant nutrition; Sheep feeding; Young animals. |
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Categoria do assunto: |
L Ciência Animal e Produtos de Origem Animal |
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Marc: |
LEADER 03863naa a2200337 a 4500
001 1519623
005 2023-07-19
008 1948 bl uuuu u00u1 u #d
024 7 $ahttps://doi.org/10.2527/jas1948.73351x$2DOI
100 1 $aBLAXTER, K. L.
245 $aThe factorization of the protein requirements of ruminants and of the protein values of feeds, with particular reference to the significance of the metabolic fecal nitrogen.$h[electronic resource]
260 $c1948
520 $aAbstract: The factorial method for the estimation of the protein requirements of animals is briefly outlined, and the divergence between such estimates for cattle and sheep and accepted feeding standards is discussed. The metabolic fecal N which can be regarded as an inevitable loss to the body has been incorporated as a term in the general factorial procedure, and it is shown that the requirement of the animal for digestible protein cannot be divorced from the character of the ration which is fed, because the latter determines the output of metabolic fecal nitrogen. The term ?available protein,? represented by the equation is suggested, to obviate the difficulties of multiple ration standards implied under a above. Available protein represents the metabolizable protein of a feed, taxed for the loss of body N which its ingestion entails and thus available for covering endogenous losses and the demands of other anabolic processes. A method of calculation of the true digestibility coefficients of feeds and classes of feeds is presented, and it is shown that the same equation may be used to predict accurately the metabolic fecal N. A table of feed composition, illustrating the computation of metabolizable, apparently digestible, and available protein is given, based on the above methods. The importance of the metabolic fecal N in determining the minimum requirement of protein of the ruminant is shown by the explanation thus afforded of the anomalous results obtained when rations high in fiber are fed to cattle. Two examples of the factorization procedure are given: for growing and fattening ewe lambs and for Holstein heifers. In both cases the effect of high quality and poor quality rations (as judged by the ratio of TDN to DM they contain) is illustrated. It is shown that the metabolic fecal loss of N may account for some 20?70 percent of the requirement of the ruminant for metabolizable protein, depending on age of the animal. The effect of this factor on the protein requirement of monogastric animals is briefly discussed. The metabolic fecal loss of N, entailing its replacement by truly digestible N, accounts for a part of the discrepancy between practical feeding standards and the factorized requirement. Nevertheless, it appears that current standards still tend to underfeed young animals and to overfeed more mature animals as far as their protein requirements are concerned. The metabolic fecal energy is presumably in the same category with reference to energy requirements of animals as the metabolic fecal nitrogen with reference to protein requirements. But before net energy requirements, or the net (or metabolizable) energy value of feeds can be corrected, information must be obtained on the magnitude of the metabolic fecal energy and its determining factors.
650 $aAnimal production
650 $aCattle feeding
650 $aFeeds
650 $aFinishing
650 $aHeifers
650 $aLambs
650 $aNutrient requirements
650 $aProtein requirement
650 $aRuminant nutrition
650 $aSheep feeding
650 $aYoung animals
650 $aNutrição
650 $aRuminante
653 $aFattening
653 $aMetodo fatorial
653 $aRequerimento proteico
700 1 $aMITCHELL, H. H.
773 $tJournal of Animal Science$gv. 7, v. 3, p. 351-372, Aug. 1948.
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