Abstract:RESUMO -O objetivo básico do presente estudo foi a determinação do fracionamento dos compostos nitrogenados presentes na extrusa de bovinos mantidos em pastagem natural, na região da Zona da Mata, MG. Foram empregados quatro novilhos fistulados no esôfago, em dois períodos experimentais durante a estação chuvosa (EC) do ano de 1996, e três destes animais em dois períodos experimentais durante a estação seca (ES) do mesmo ano. Para determinação do fracionamento dos compostos nitrogenados (frações A, B 1 , B 2 ,… Show more
“…R. Webster) taken during the winter in the Zona da Mata Region of Minas Gerais State, Brazil. Therefore, the variability of this fraction in the pasture is difficult to predict, e.g., Vieira et al (2000a) analyzed esophageal extrusa samples collected from a natural grassland containing U. decumbens and found 11 g kg −1 DM in the dry season and 40 g kg −1 DM in the rainy season. That variability led Higgs et al (2015) to state that in loco evaluation of the protein fractions of the forage resources is the first strategy to predict animal performance more accurately if the feed library does not contain robust estimates of the feed resources available.…”
Section: Discussionmentioning
confidence: 99%
“…Esophageal extrusa samples were collected in the morning for seven days into nylon bags with plastic-screen at the bottom to drain excess saliva (Scales et al, 1974;Vieira et al, 2000a). The nylon bags were adapted to provide flexibility and comfort to the animals during grazing.…”
-This experiment was conducted to evaluate the degradation kinetics and microbial efficiency of beef cattle grazing on low-quality forage and receiving supplements with different levels of rumen undegradable protein (RUP). The animals grazed on palisade grass pasture solely or this pasture and supplement containing 40 or 60 g of RUP per 100 g of crude protein (CP). The degradation profiles of neutral detergent fiber, fiber carbohydrates, and neutral detergent insoluble protein were interpreted kinetically by using a decreasing logistic model. Treatments (no supplement, or RUP at 40 or 60 g −1 100 g CP) did not affect rumen fill; however, the increase in the indigestible fiber carbohydrate fraction that occurred at the expense of the digestible fiber carbohydrate fraction resulted in a greater rumen fill effect. The palisade grass showed a significant proportion of its nitrogen in the form of slowly degradable protein as neutral detergent insoluble protein, which amounted to 26 g per 100 g CP. Supplementation with 40 g of RUP per 100 g CP decresead the indigestible fraction of the low-quality forage. However, the absence of a rumen-fill effect demonstrates that the additional supply of nutrients contributes greatly to increasing growth efficiency and use of the available energy from the forage by the ruminal microorganisms.
“…R. Webster) taken during the winter in the Zona da Mata Region of Minas Gerais State, Brazil. Therefore, the variability of this fraction in the pasture is difficult to predict, e.g., Vieira et al (2000a) analyzed esophageal extrusa samples collected from a natural grassland containing U. decumbens and found 11 g kg −1 DM in the dry season and 40 g kg −1 DM in the rainy season. That variability led Higgs et al (2015) to state that in loco evaluation of the protein fractions of the forage resources is the first strategy to predict animal performance more accurately if the feed library does not contain robust estimates of the feed resources available.…”
Section: Discussionmentioning
confidence: 99%
“…Esophageal extrusa samples were collected in the morning for seven days into nylon bags with plastic-screen at the bottom to drain excess saliva (Scales et al, 1974;Vieira et al, 2000a). The nylon bags were adapted to provide flexibility and comfort to the animals during grazing.…”
-This experiment was conducted to evaluate the degradation kinetics and microbial efficiency of beef cattle grazing on low-quality forage and receiving supplements with different levels of rumen undegradable protein (RUP). The animals grazed on palisade grass pasture solely or this pasture and supplement containing 40 or 60 g of RUP per 100 g of crude protein (CP). The degradation profiles of neutral detergent fiber, fiber carbohydrates, and neutral detergent insoluble protein were interpreted kinetically by using a decreasing logistic model. Treatments (no supplement, or RUP at 40 or 60 g −1 100 g CP) did not affect rumen fill; however, the increase in the indigestible fiber carbohydrate fraction that occurred at the expense of the digestible fiber carbohydrate fraction resulted in a greater rumen fill effect. The palisade grass showed a significant proportion of its nitrogen in the form of slowly degradable protein as neutral detergent insoluble protein, which amounted to 26 g per 100 g CP. Supplementation with 40 g of RUP per 100 g CP decresead the indigestible fraction of the low-quality forage. However, the absence of a rumen-fill effect demonstrates that the additional supply of nutrients contributes greatly to increasing growth efficiency and use of the available energy from the forage by the ruminal microorganisms.
“…A capacidade de degradação da fibra é extremamente importante em ruminantes alimentados exclusivamente com gramíneas tropicais, pois a fibra representa a maior parte dos carboidratos totais (CT) do pasto (Vieira et al, 2000), como observado na grama-estrela cv. Africana, que apresentou 83,2% de carboidratos fibrosos (CF) em relação aos carboidratos totais (CT).…”
Section: Resultsunclassified
“…Malafaia et al (1997) encontraram valor de 38,72% (B 1 + B 2 ) para o capim-tifton 85, próximo (38,54%) ao encontrado por Cabral et al (2000a) para o mesmo capim com altura de corte de 30 cm. A taxa de degradação da fração B 1 estimada (Tabela 2) foi muito elevada, por isso, considerou-se que a taxa degradação desta fração tendia para o infinito, ou seja, na escala de tempo adotada, foi demasiadamente rápida, pois é considerada prontamente disponível para os microrganismos do rúmen (Russell et al, 1992;Vieira et al, 2000).…”
Section: Resultsunclassified
“…Isso pode ser endossado pelo fato de a principal contribuição energética ser originária da fração B 2 ', cuja característica é a lenta degradação no rúmen. Essa situação propiciaria melhor sincronização entre disponibilidade de nitrogênio e a quantidade de energia necessária para o crescimento microbiano (Vieira et al, 2000), promovendo maior aporte de proteína microbiana para o intestino delgado, o que melhoraria o desempenho animal.…”
RESUMO -Objetivou-se avaliar nutricionalmente a grama-estrela ( Cynodon nlemfuensis) cv. Africana utilizada sob pastejo rotacionado por vacas leiteiras. Dez vacas mestiças foram manejadas em 2 ha de grama-estrela e divididas em 11 piquetes/ha. O período de pastejo foi de três dias e os 30 subseqüentes foram destinados à recuperação da pastagem. Durante o período experimental, os animais foram ordenhados duas vezes ao dia e receberam suplementação com 2 kg de concentrado. Amostras representativas do pasto ingeridas (extrusa) foram colhidas para determinação de sua composição nutricional. O consumo de matéria seca (MS) pelos animais foi estimado utilizando-se cromo e a MS indigestível como indicadores externo e interno. O desempenho individual das vacas foi avaliado pela produção de leite diária e pela pesagem dos animais. A dinâmica da matéria alimentar foi estimada com base nas técnicas in vitro gravimétricas, de produção cumulativa de gases da fermentação microbiana e da estimativa da cinética de passagem das fases sólida e líquida. A quantidade de energia líquida total (ELt), em MJ/dia, atendeu à demanda energética exigida pelos animais. Os valores de proteína metabolizável (PM) preditos corresponderam ao suprimento de 91% da PM exigida por esses animais. As predições das exigências em macrominerais atenderam apenas 75% do Ca exigido, mas atenderam às exigências dos demais macrominerais. A grama-estrela atende à demanda energética nutricional de mantença e produção de 11,7 kg de leite por dia. Nas circunstâncias estudadas, é necessário suplementar nutrientes que complementem a PM e Ca não atendidos completamente. O teor e as características cinéticas da fibra não causam repleção ruminal e restrição sobre o consumo de vacas leiteiras em pastejo.Palavras-chave: análise bromatológica, desempenho animal, forragem tropical
Nutritional analysis of stargrass cv. Africana for dairy cattle under rotational grazingABSTRACT -An nutritional analysis of stargrass cv. Africana fed dairy cattle under rotational grazing was evaluated in this research. Ten Holstein-Zebu crossbred cows were managed in 2 ha covered with the grass and divided in 11 paddocks /ha with three grazing days 30 days of resting period. During the experimental period the animals were milked twice a day for 16 days and were feed two kg of concentrate. Representative samples of the pasture consumed (extrusa) were taken and determined the nutritional composition. The dray matter intake of the animals was estimated by means of chromium and indigestible DM as external and internal markers. The individual performance of the cows was evaluated by daily milk production and by weighting the animals. The food matter dynamics was estimated with gravimetric in vitro techniques, cumulative gas production from microbial fermentation and estimates of the passage kinetics of solid end liquid phases. The amount of total net energy (NEt) in MJ/d meet the energetic requirement by the animals. The predicted values for metabolizable protein (MP) corresponded to the supply of ...
The objective of this study was to identify by microhistological technique the reference chemical components for use as indicators of the nutritive value of Caatinga plants forage grazed by sheep throughout the year. A flock of twenty mixed-race meat ewes, multiparous, in production, with an average 34.84 ± 1.75 kg live weight and 36 months of age was assigned to supplement treatment of 0, 200, 350, and 500 g concentrate/head/day for 3 years. The experiment was designed as a randomized complete design with repeated measures over time. Supplementation with concentrate did not influence chemical composition of selected forage. In contrast, season heavily influenced diet chemical composition. Canopy stratum, season, and plant botanical family of selected species affected forage chemical composition selected by ewes. The ewes selected forage with greater nutritive value during the rainy season. Based on principal component analysis of the nutritive value of the primary forage species selected, ewes preferentially grazed plants contained greater neutral detergent fiber, acid detergent fiber, crude protein (CP), C fraction of nitrogenous compounds, and carbohydrate fractions A + B1 and C compared to the average native Caatinga herbage. Rangeland botanical composition and ewe diet varied during the year, affecting forage nutrients on offer, with the best diet selected during the rainy season because of the presence of dicotyledonous herbaceous species rich in CP as well as soluble carbohydrates and nitrogenous compounds. Concentrate supplement strategies for ewes on rangelands, such as Caatinga, should be determined by herbaceous species nutritive value during the rainy season and deep-rooted perennial dicotyledons during the dry season. These include the need to monitor ewe selection of forage species and their nutritive value, which is effectively accomplished with fecal microhistological techniques.
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