Evaluation of neutral detergent fiber contents in forages, concentrates and cattle feces ground at different particle sizes and using bags made from different textiles

Two experiments were carried out to evaluate the effects of particles sizes on contents of neutral detergent fiber (NDF) by using nylon bags F57 (Ankom®) and non-woven textile (NWT 100 g/m²). In the first experiment, to check contents of NDF obtained with each one of the textilles, quantitative filter paper (purified cellulose) was used as analytical standard. The material was processed in a 1 or 2 mm and put in the bags in a ratio of 20 mg of dry matter/cm² of surface. The analyses were performed in a fiber analyser (Ankom220) and using a heat-stable a-amylase. No effects of particles sizes were found. In the second experiment, it was used 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 of animals fed diets containing 15 or 50% of concentrate. The samples were prepared, put in bags, and analyzed as described in the previous experiment. In both experiments, the smallest contents of NDF were found by using nylon bags, indicating loss of particles through the bag porosity. It is suggested grind of samples by using 1-mm screen sieve, which provides efficient extraction of cell content by the action of neutral detergent and a greater specific surface by the action of the heat-stable a-amylase enzyme. The use of particles ground at 2-mm overestimates NDF contents.Foram realizados dois experimentos objetivando-se avaliar a influência do tamanho das partículas sobre os teores de fibra em detergente neutro (FDN) utilizando-se sacos de náilon, F57 (Ankom®) e tecido-não-tecido (TNT 100 g/m²). No primeiro experimento, com o intuito de aferir os teores de FDN obtidos com cada um dos tecidos, utilizou-se papel-filtro quantitativo (celulose purificada) como padrão analítico. O material foi processado em 1 e 2 mm e acondicionado nos sacos seguindo-se a relação de 20 mg de matéria seca/cm² de superfície. Utilizou-se aparelho analisador de fibras (Ankom220), empregando-se a-amilase termoestável. Não foram verificados efeitos do tamanho de partículas. Contudo, perdas de partículas significativas foram verificadas com o uso do náilon. No segundo experimento foram utilizadas amostras de forragem (feno de capim-braquiária, cana-de-açúcar, feno de coastcross, palha de milho, silagem de milho e capim-elefante cortado aos 50 dias e 250 dias de rebrotação), alimentos concentrados (sorgo grão, glúten de milho, polpa cítrica, farelo de algodão, farelo de soja, farelo de trigo, milho grão, soja grão e casca de soja) e fezes bovinas oriundas de animais alimentados com dietas contendo 15 e 50% de concentrado. As amostras foram preparadas, acondicionadas e analisadas como descrito no experimento anterior. Os menores teores de FDN foram encontrados com o uso de sacos de náilon, o que indica perda de partículas pela porosidade do saco. Recomenda-se a moagem de amostras em peneiras de porosidade 1 mm, o que propicia a extração eficiente do conteúdo celular pela ação do detergente neutro e maior superfície específica para ação da a-amilase termoestável. O uso de partículas processadas a 2 mm conduz à superestimação dos teores de FDN

Determinação da digestibilidade de nutrientes através da técnica do "saco de nylon" mais pepsina

Procurou-se verificar se a digestão de alimento em saco de "nylon", acrescida por tratamento com pepsina, seria equivalente à digestão obtida pelo método direto clássico, o de coleta total de fezes, já determinado anteriormente com ovinos. Seguiu-se um delineamento experimental em blocos ao acaso, com 6 repetições e 4 tratamentos, ou seja, tratamento A: ração contendo 100% de feno de capim de Rhodes; B: 85% de feno de Rhodes mais 15% de farelo de côco; C: 70% de feno de Rhodes mais 30% de farelo de côco; e D: 100% de farelo de côco. O animal fistulado utilizado para teste foi um bovino adulto, macho, de raça holandesa; o tempo de permanência do saco de "nylon" no rume foi de 72 horas; e a dieta consistiu em feno de Rhodes à vontade mais 2kg de farelo de coco por dia. Os resultados foram analisados através de análise da variância e curvas de regressão, e a comparação entre métodos de digestibilidade pelo teste de Tukey. Houve influência da associação de alimentos sobre a digestibilidade da fibra bruta (FB) e dos extrativos não nitrogenados (ENN), mas não sobre as demais frações - matéria seca (MS), extrato etéreo (EE) e proteína bruta (PB). A digestibilidade da fibra diminuiu com a inclusão e o acúmulo do nível de farelo na dieta. Não houve equivalência consistente entre os métodos testados de digestiblidade, variando ou não conforme o nutriente e o tratamento considerado. De modo geral, a inclusão de aproximadamente 15% de farelo de côco (tratamento B) favoreceu o melhor aproveitamento da dieta."Nylon bag" technique, followed by 48 hours of chloridric pepsin digestion, was tried for determination of the digestibility of proximate nutrients of Rhodes grass hay (Chloris gayana, Kunth, cv. callide) and coconut caque meal, and compared with results from "in vivo" method. In a randomized blocks design, 100% of Rhodes grass, and mixtures of 85% and 70% of the grass hay with 15%, and 30% of coconut cake, and 100% coconut cake, made up four treatments (A, B, C and D, respectively). The coefficients of digestibility for Dry Matter and for proximate nutrients in treatments A, B and C, determined through nylon bags in bovine rumen, were compared to the coefficients determined by total faces collection, in sheep. It was observed and concluded that: a) Position of samples along the supoort-bars inside rumen, as well as dfferent periods of animal usage, had no influence on the results; b) The calculated proportions of coconut in the mixture to obtain best digestibility were 17.48% for Dry Matter, 21.10% for Ether Extract, 29.01% for Crude Protein, and 16.49% for Non Nitrogenous Extrat. Crude Fiber digestibility decreased linearly as the coconut proportion in the mixture increased; c) "Nylon bag" and "in vivo" methods gave similar coefficients of digestibility for Crude Fiber for all treatments; for other nutrients, however, there were differences depending on treatments; d) TDN values for coconut cake meal, determined through "nylon bags" were 68.76% taking the average coefficients of digestibility from treatments B and C, and 68.08% from treatment D; "in vivo", the average from B and gave 71.06% of TDN; such a small difference in NDT suggests to have had no interference of foods on digestibility; e) NDT calculate for Rhodes grass hay was 58.38% "in nylon bags", and 44.81% "in vivo", when treatment A was the only one considered; thus, it could be concluded that nylon bag plus pepsin method did not work for Rhodes hay

Evaluation of ruminal degradation profiles of forages using bags made from different textiles

The objective of this study was to evaluate the in situ degradation profiles of dry matter (DM) and neutral detergent fiber (NDF) of different forages using nylon (50 µm), F57 (Ankom®) and non-woven textile (NWT - 100 g/m²) bags. Eight forage samples were used: sugarcane, corn silage, elephant grass cut at 50 and 250 days of regrowth, corn straw, signal grass hay, coast cross hay, and fresh alfalfa. Samples were incubated for 0, 3, 6, 12, 18, 24, 48, 72, 96, 120, 144, 168, 192, 216, 240, and 312 hours. Two bags of each textile were used at each incubation time, totaling 768 bags, using two crossbred Holstein × Zebu steers fitted with ruminal canullae. There was difference in the common rate of lag and degradation (λ) of DM for all forages, except for 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. Greater estimates were obtained using nylon. Degradation profiles of DM and NDF must not be evaluated using F57 and NWT. These textiles underestimate the degradation rate due to constraints regarding exchange between bags' content and rumen environment