Utilização de tecidos na avaliação de compostos fibrosos e na degradação ruminal in situ de alimentos para ruminantes

• Ano de defesa: 2010
• Autor(a) principal: Valente, Tiago Neves Pereira
• Orientador(a): Detmann, Edenio
• Banca de defesa: Valadares, Rilene Ferreira Diniz , Rennó, Luciana Navajas
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Zootecnia
• Departamento: Genética e Melhoramento de Animais Domésticos; Nutrição e Alimentação Animal; Pastagens e Forragicul
• País: BR
• Palavras-chave em Português: Fibra insolúvel; Indicadores internos; Sistema detergente
• Palavras-chave em Inglês: Insoluble fiber; Internal markers; Detergent system
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::NUTRICAO E ALIMENTACAO ANIMAL
• Link de acesso: http://locus.ufv.br/handle/123456789/1731

This thesis was prepared from four papers. The first one was carried out to evaluate the effects of different particles sizes on neutral detergent fiber (NDF) content using bags made from the textiles: nylon (50 μm), F57 (Ankom®), and non woven textile (NWT 100 g/m²). In the first experiment, quantitative filter paper (purified cellulose) was used as analytical standard to check NDF analysis in the bags. The samples were processed (1- or 2-mm) and put in the bags in a ratio of 20 mg of dry matter/cm² of surface. The extraction procedure was carried out in a fiber analyzer (Ankom220) using a heat-stable α-amylase. No effects of different particles sizes were found. Particles loss was observed for nylon bags. In a second step level, samples of forage (signal grass hay, sugar cane, coastcross hay, corn straw, corn silage, and elephant grass at 50 and 250 days of growing after cutting), concentrate feeds (sorghum grain, gluten meal, citrus pulp, cottonseed meal, soybean meal, wheat bran, corn grain, whole soybean, and soybean hulls), and feces of cattle fed diets containing 15 or 50% of concentrate, were used. The samples were prepared, put in the bags, and analyzed as described for the previous experiment. In a general way, the smaller NDF results were found with nylon. It could indicate particles loss caused by textile porosity. It is recommended that samples be ground using 1-mm screen sieve, which implicates higher specific surface and allows better cellular content extraction by detergent and action of the heat-stable α-amylase. In this context, the use of particles ground at 2-mm causes overestimation of NDF contents. In the second paper the objective was to evaluate the effect of different textiles (nylon -50 μm; F57; and NWT on NDF content estimates using quantitative filter paper as purified cellulose standard. It was simulated different sample compositions using starch, pectin, casein or soybean oil. The quantitative filter paper was processed in 1-mm screen sieve. The extraction procedure was carried out in fiber analyzer (Ankom220®). Four experiments were carried out with additions of the different ingredients together filter paper: corn starch at 15 or 50%; pectin at 15 or 50%; casein at 10 or 30%; and soybean oil at 0, 5, 10, 15, 25 or 50%, on dry matter basis (DM); respectively. The samples were put in the bags in a ratio of 20 mg of DM/cm² of surface. When pertinent, according to treatments, heat-stable α-amylase was used. It were found similar NDF results by using NWT or F57. The nylon textile caused loss of fibrous particles and produced inaccurate estimates of NDF contents. The heat-stable α-amylase is recommended in the evaluation of NDF contents of starch containing samples. The pectin and casein were totally removed by neutral detergent solution. Samples containing levels up to 10% of oil caused overestimated NDF contents. In the third paper the objective was to evaluate the estimate the contents of internal markers indigestible dry matter (iDM), indigestible neutral detergent fiber (iNDF) and indigestible acid detergent fiber (iADF) in samples of cattle feed and feces processed at different particle sizes (1-, 2-, and 3 - mm) using bags made by the textiles nylon, F57, and NWT in a in situ procedure. It were used eight samples of concentrates, seven samples of forages and two samples of cattle feces. The samples were put in the bags according to a ratio of 20 mg of DM/cm² of surface. It were used three bags of each textile and particle sizes, totality 405 bags. The bags were submitted to 264 hours in situ rumen incubation. The contents of markers were sequentially evaluated. Blank bags were used for microscopic evaluation of textile integrity and for evaluation of the physical resistance. The presence of contaminants caused high variability of iDM results, which indicated that its use as internal marker is not recommended. F57 and NWT presented similar estimates of iNDF and iADF, while nylon underestimated the concentration of indigestible compounds. This result is probably associated with particle loss. The nylon showed decrease in physical resistance after each analytical step. That pattern leads to an increase of the rupture probability, mainly after acid detergent extraction. It was recommended the milling of samples at 2 - mm particles size to evaluate indigestible compounds through in situ procedures. In the fourth paper it were evaluated the in situ degradation profiles of DM and NDF of different forages using bags made from nylon (50 μm), F57 and NWT. Eight forages samples were used: sugarcane, corn silage, elephant grass cut at 50 and 250 days of regrowth, corn straw, signal grass hay, coastcross hay, and fresh alfafa. The samples were incubated for 0, 3, 6, 12, 18, 24, 48, 72, 96, 120, 144, 168, 192, 216, 240, and 312 hours. Two bag of each textile were used at each incubation time, totalizing 768 bags, using two crossbred Holstein x Zebu steers fitted with ruminal canullae. There was difference in the common rate of lag and degradation (λ) of DM for all forages, excepting sugarcane. In general, higher λ estimates were obtained using nylon, followed by NWT and F57. Concerning NDF degradation profiles, differences in λ were observed for all forages. Higher estimates were obtained using nylon. Degradation profiles of DM and NDF must be not evaluated using F57 and NWT. These textiles underestimate the degradation rate because there are limitations regarding exchange between bags inside and rumen environment.