In vitro degradation of neutral detergent fiber of high-quality tropical forage according to supplementation with different nitrogenous compounds
The objective of this work was to evaluate the in vitro degradation dynamics of neutral detergent fiber (NDF) of high-quality tropical forage according to supplementation with different nitrogenous compounds sources. A signal grass sample harvested during rainy season was used as basal forage. Casei...
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| Published in: | Revista brasileira de zootecnia Vol. 38; no. 5; pp. 964 - 971 |
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| Main Authors: | , , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
Sociedade Brasileira de Zootecnia
01-05-2009
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| Subjects: | |
| Online Access: | Get full text |
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| Summary: | The objective of this work was to evaluate the in vitro degradation dynamics of neutral detergent fiber (NDF) of high-quality tropical forage according to supplementation with different nitrogenous compounds sources. A signal grass sample harvested during rainy season was used as basal forage. Casein was used as true protein source and urea:ammonium sulfate (U:AS, 9:1) mixture (urea) as non-protein nitrogen source. The first three supplements were the addition of 0.5, 1.0 and 2.0 mg of casein per mL of final incubation solution. The urea was added to the same amount of protein supplied by equivalent levels 0.5, 1.0 and 2.0 mg/mL of casein. In total, seven treatments were evaluated, including a control (only grass). The supplements were evaluated in a simulated rumen environment by in vitro incubation, and submitted to different incubation times: 0, 3, 6, 9, 12, 24, 36, 48, 72, and 96 hours. The procedure was repeated four times, making a total of four evaluations per incubation time for each treatment. The incubation residues were evaluated for NDF contents and interpreted through a non-linear logistic model. Casein supplementation of 0.5 mg/mL increased the degradation rate of potentially digestible NDF (kpdNDF) by 1.1%. The addition of 1.0 and 2.0 mg/mL of casein provided an inhibitory effect on the estimates of this parameter in comparison to the control (-6.4 and -9.1% respectively). Moreover, the addition of urea, regardless the supplementation level, increased kpdNDF around 7.6%. The ammonia nitrogen (AN) concentration in the medium was increased by supplementation. However, supplementation with urea, even based on the same crude protein levels used with the supplementation with casein, has given higher ammonia nitrogen values in the incubation medium.
Objetivou-se avaliar a dinâmica de degradação in vitro da fibra em detergente neutro (FDN) de forragem tropical de alta qualidade em função de suplementação com compostos nitrogenados. Como forragem basal, utilizou-se amostra de capim-braquiária colhida durante a estação chuvosa; como fonte de proteína verdadeira, caseína (0,5; 1,0 e 2,0 mg/mL de solução final de incubação); e, como fonte de nitrogênio não-protéico, mistura uréia:sulfato de amônia (U:SA; 9:1) (uréia). A uréia foi adicionada considerando a mesma quantidade de equivalentes protéicos fornecidos pelos níveis 0,5; 1,0 e 2,0 mg/mL de caseína. No total, incluindo o controle (somente forragem), obtiveram-se sete tratamentos, que foram avaliados em ambiente ruminal simulado por incubação in vitro, durante 0, 3, 6, 9, 12, 24, 36, 48, 72 e 96 horas. O procedimento foi repetido quatro vezes, perfazendo quatro avaliações por tempo de incubação para cada tratamento. Os resíduos de incubação foram avaliados quanto ao teor de FDN e interpretados por modelo logístico não-linear. A suplementação com caseína no nível 0,5 mg/mL aumentou em 1,1% a taxa de degradação da FDN potencialmente degradável (kFDNpd), enquanto, nos níveis 1,0 e 2,0 mg/mL, observou-se efeito inibitório sobre as estimativas deste parâmetro (-6,4 e -9,1%, respectivamente). Por outro lado, a adição isolada de uréia ao meio, independentemente do nível, ampliou em média 7,6% a kFDNpd. A concentração de nitrogênio amoniacal (NA) no meio aumentou com a suplementação, contudo, considerando-se os mesmos níveis de proteína bruta obtidos com a suplementação com caseína, a suplementação com uréia conferiu valores superiores de nitrogênio amoniacal ao meio de incubação. |
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| Bibliography: | 10.1590/S1516-35982009000500025 http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-35982009000500025 |
| ISSN: | 1516-3598 1806-9290 1806-9290 1516-3598 |
| DOI: | 10.1590/S1516-35982009000500025 |