Avaliação do teor de lignina em forragens tropicais por diferentes métodos analíticos e sua associação com a degradação da fibra insolúvel

• Ano de defesa: 2010
• Autor(a) principal: Gomes, Daiany Iris
• Orientador(a): Detmann, Edenio
• Banca de defesa: Fukushima, Romualdo Shigueo , Paulino, Mário Fonseca
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Zootecnia
• Departamento: Genética e Melhoramento de Animais Domésticos; Nutrição e Alimentação Animal; Pastagens e Forragicul
• País: BR
• Palavras-chave em Português: Degradação ruminal; Fibra em detergente neutro; Lignina
• Palavras-chave em Inglês: Ruminal degradation; Neutral detergent fiber; Lignin
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::NUTRICAO E ALIMENTACAO ANIMAL
• Link de acesso: http://locus.ufv.br/handle/123456789/5613

The objective of this work was to evaluate the lignin contents in tropical forage using the methods of acid sulfuric lignin (ASL), potassium permanganate lignin (PL), Klason lignin (KL) and acetyl bromide soluble lignin obtained from cell wall (ABLcw) and from acid detergent residue (ABLad) and their association with parameters of neutral detergent fiber (NDF) degradation. It were evaluated ten grass samples: elephant grass (Pennisetum purpureum), signal grass (Brachiaria decumbens), torpedo grass (Panicum repens), Korovinia grass (Brachiaria humidicula), gamba grass (Andropogon gayanus), aruana grass (Panicum maximum cv. Aruana), mombaça grass (Panicum maximum cv. Mombaça), xaraés grass (Brachiaria brizantha cv. Xaraés), tifton-85 (Cynodon sp.), and massai grass (Panicum maximum cv. Massai); and ten legume samples: perennial peanut (Arachis pintoi), alfafa (Medicago sativa), leucaena (Leucaena leucocephala), galactia (Galactia striata), lablab bean (Dolichos lablab), butterfly pea (Centrosema pubescens), glycine (Glycine weghtii), gliricidia (Gliricidia sepium), Brazilian lucerne (Stylosantes guianenensis) and guandu (Cajanus cajan). All samples were taken through a cutting near to ground in December of 2008. The plants were 45-days regrowth. The lignin contents obtained by gravimetric methods were also estimated corrected for nitrogenous compounds. In this case, they were assigned as ASLp, PLp, and KLp. The indigestible NDF (iNDF), the fractional degradation rate of potentially degradable NDF (kd), and the discrete lag of NDF degradation were obtained by an in vitro assay. The correction for nitrogenous compounds decreased (P<0.05) the contents of ASL, KL and PL. The differences between corrected and crude values were more prominent for KL. The protein contents of KL were found similar (P>0.05) to neutral detergent insoluble protein. There was interaction effect (P<0.05) between analytical method and forage group on lignin contents. Considering the contents as g/kg DM, differences between grasses and legumes were pointed out (P<0.05) by ASLp and PLp, being the higher values associated with legumes, and by ABLcw, which caused higher values in grasses. For grasses, highest lignin contents (P<0.05) were obtained with KLp, which was followed by PLp and ABLcw, that did not differ each other (P>0.05), ASLp, and ABLad. For legumes, highest contents (P<0.05) were obtained with KLp, followed by LPp, ASLp, ABLcw, and ABLad. These last two were not different (P>0.05). The lignin estimates obtained by ASLp and PLp shown similar association pattern (P<0.05) with iNDF, kd, and LAG. There was no difference in both methods for grasses and legumes regarding intercept and slope of adjusted regression (P>0.05). Stronger correlations were observed between PLp and degradation parameters of NDF compared to ASLp. The KLp estimates did associate with alldegradation parameters (P<0.05). However, there were differences between grasses and legumes regardingintercept of adjusted regression (P<0.05). Legumes presented higher iNDF and LAG, and lower kd. The strongest correlation coefficients were obtained using LPp and KLp estimates. The ABLcw contents did not did not presented functional relationships with NDF degradation parameters (P>0.05), where only the average differences between forage groups were detected. It was verified relationship (P<0.05) between ABLad contents and iNDF. However, no difference between grasses and legumes was pointed out by adjusted regression (P>0.05). Nevertheless, the correlation coefficient was weaker compared to ones obtained using ASLp, KLp, and PLp. There were no functional relationships between ABLcw and degradation parameter of NDF (P>0.05). In this case, it was only detected the average difference between forage groups. It was concluded that gravimetric methods ASL, PL and KL produce residues that contain significant contaminant nitrogenous compounds. More accurate estimates of lignin content could be obtained when correction for residual nitrogen is done. This is particularly necessary for KL. Associations between lignin and degradation parameters of NDF are better recognized when KLp and PLp methods are employed.