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ARS Home » Research » Publications at this Location » Publication #67058
Title: HISTOCHEMICAL FRACTIONATION OF CEREAL STRAW TISSUE USING PECTINASE/ MECHANICAL DISRUPTION AND RELATIONSHIP WITH RUMEN MICROBIAL DEGRADATION IN VITRO

Author
item OHLDE, GERHARD - UNIVERSITY OF HOHENHEIM
item Akin, Danny
item BECKER, KLAUS - UNIVERSITY OF HOHENHEIM

Submitted to: Journal of the Science of Food and Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/7/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Tests for feed quality are often expensive and labor-intensive, and simple, inexpensive tests are needed in programs to improve feed quality and reduce production costs. Collaborators in ARS and at the University of Hohenheim, Germany, evaluated a combined mechanical/enzyme method to test quality of a series of cereal straws. Results established that this method correlated well with the standard in vitro fermentation method and offered promise as a low-cost, rapid technique to improve testing methods for feed quality.

Technical Abstract: The non-lignified (acid-phloroglucinol-negative) parts of the parenchyma in four different cereal straw species were removed by a 24 h incubation in pectinase-buffer solution (pH 4.2, 35C) followed by a mechanical treatment and filtration. The losses were determined gravimetrically. Light micrographs of transverse sections of internodes showed the impact of the applied pectinase method on straw tissues whereas scanning electron micrographs indicated that those portions of tissues that were removed by the pectinase method corresponded with those totally degraded by rumen microbes. Simple correlation coefficients between pectinase-degraded material and in vitro digestibility of dry matter (IVDDM) of winter- and spring-barley, spring-wheat and teff straw ranged from r = 0.84 to 0.89. Thus, the determined weight losses by the pectinase method accounted for approximately 75 percent of the total variance of the IVDDM. Transmission electron micrographs showed a partial degradation of the secondary walls o sclerenchyma cells by rumen microorganisms in the cereal straws, but these walls were not degraded by the pectinase method. In general, treatment with pectinase followed by mechanical disruption can be an accurate, simple and low-cost tool in screening large sets of straw samples with respect to their degradability in vitro.