Fracionamento e degradabilidade ruminal de proteÃnas e carboidratos de forrageiras de gÃnero Cynodon. / Fractionating and ruminal degradability of proteins and carbohydrates of forage plants of the genus Cynodon.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

The work was conduced in the Animal Science Department of the Federal University of Lavras, with the objective of evaluating the fractionating of protein and carbohydrates and the kinetics of the ruminal degradation of forage grasses of the genus Cynodon (Coastcross, Tifton 85 and Tifton 68). The experiment was conduced for two consecutive years, in two rainy seasons, in the first year, the beginning being on the November 12th of 2002 and in the second year on the October 30th of 2003. The experimental design was in randomized blocks with 3 treatments and five blocks, each treatment being replicated four time within the block. The contents of dry matter (DM), crude protein (CP), ether extract (EE), mineral matter (MM), neutral detergent fiber (NDF), acid detergent fiber (ADF), neutral detergent insoluble nitrogen (NDIN), acid detergent insoluble nitrogen (NIDA), cellulose, hemicellulose and lignin were determined. The forage plants presented, in a similar manner, fractions of protein of high solubility (A) and slow degradation (B3). The fraction of rapid degradation protein (B1) of Tifton 85 was larger in relation to Tifton 68 and Coastcross, respectively. Both Coastcross and Tifton 68 presented the largest fractions of intermediary degradation (B2), which may represent a high protein amount for ruminal degradation and for the small intestine. Low unavailable fractions (C) were verified for the studied forage plants, but, it is worthwhile to stressing that Tifton 68 was the one which presented the lowest fraction. Coastcross presented the largest fraction of non-fibrous carbohydrates (A + B1) relative to the other forages plants (Tifton 85 and Tifton 68), indicating, then, its increased efficiency in supplying readily available energy. The Fraction available fiber (B2) was similar among the three forages. The smallest fraction of unavailable fiber (C) was found for Coastcross, followed by Tifton 85 and Tifton 68, respectively. The behavior of the kinetics of degradation ruminal reinforces the high solubility found for the proteins with values of DE satisfactory for the three forages, with high rates of soluble fraction and potentially degraded in the rumen, also presenting potentially high proportions of fiber potentially degraded in the rumen, accounting for the results found for carbohydrate fractionating. Considering the results obtained for the fractions protein and carbohydrate and the study of the kinetics of ruminal degradation, the forage plant that presented the best characteristics, warranting an improved synchronism of fermentation between carbohydrates and proteins in the rumen, leading to a better ruminal energy adequacy, consequently, promoting a better microbial growth was Coastcross. As second and third options, Tifton 85 and Tifton 68 are suggested, respectively.

ASSUNTO(S)

in situ fracionamento zootecnia cynodon fractionating carboidrato cynodon nitrogen carbohydrates nitrogÃnio

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