الفهرس 
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Abstract
The present study was carried out at the advanced laboratory of Animal Nutrition,
Animal and Fish production Department, Faculty of Agriculture, University of Alexandria.
The objective of this work was to identify the feasibility of using fibrolytic enzymes
(xylanase and a mixture of xylanase and glucanase to improve the nutritive value of three
types of poor-quality roughages and the extent of the impact on rumen fermentation and gas
production Three roughages material namely rice straw, sugar- cane tops (leaves) and wheat
straw were used. Three levels of enzymes (3, 6 and 9) mg/g DM were used. The tested
roughages sprayed with exogenous fibrolytic enzymes (EFE) at different levels 12h prior to
starting the chemical Composition and in vitro studies.
The obtained results were as follow:
Chemical Composition (OM, OM, CP, EE, CF, Ash and NFE ) for the three tested
roughages were almost not affected by enzymes treatment except crude fiber that tended to be
affected by enzyme treatment, and resulting in a reduction with rice straw treated with
xylanase (41.64, 40.92, 41.06 and 40.41% for 0, 3, 6 and 9 mg/g DM ,respectively ) and for
the treatment with the mixture of the two enzymes used, the values were (41.64, 41.25,
40.04, and 40.97% for 0, 3, 6 and 9 mg/g DM, respectively). With sugar- cane tops, the
values of crude fiber were (46.92, 43.31, 42.36 and 44.99% for 0, 3, 6 and 9 mg/g DM,
respectively) for xylanase and (46.92,42.80, 44.13 and 43.29% for 0, 3, 6 and 9 mg/g DM,
respectively) for the mixture of xylanase and glucanase. Crude fiber in wheat straw showed
better response by treatment even with xylanase (45.54,37.61,41.62 and 43.65% for 0, 3, 6
and 9 mg/g DM, respectively) or a mixture of xylanase and glucanase (45.54,41.23, 42.75
and 43.01% for 0, 3, 6 and 9 mg/g DM, respectively).
There were no significant responses for fiber reactions (ADF, NDF, cellulose and
hemicellulose ) among treatments, ADL was significantly decreased in the treated rice straw
(8.25, 2.70, 5.02 and 7.95 for 0, 3, 6, and 9 mg/g DM, respectively) in xylanase treatment or
with the mixture of xylanase and glucanase (8.25, 4.01, 4.44 and 4.09 for 0, 3, 6, and 9 mg/g
DM, respectively), NDF values for the treated rice straw were numerically decreased even
with xylanase (77.52,74.62, 74.72 and 74.72% for 0, 3, 6, and 9 mg/g DM, respectively) or a
mixture of xylanase & glucanase (77.52,73.90,76.33 and 73.27% for 0, 3, 6, and 9 mg/g DM,
respectively) .
Individual volatile fatty acids (acetic, propionic and butyric, mmol / L) were
significantly increased for the three tested roughages and with all enzyme levels used.
Ammonia nitrogen (NH3 – N mg / 100 ml) concentration tended to be significantly
decreased for rice straw and sugar-cane tops but an opposite trend was recorded for wheat
straw in which NH3 - N tended to be significantly increased almost at all levels of enzymes
treatment.
The rate of digestibility of dry matter and organic matter did not show a clear trend in
either the treated roughages or the levels of enzymes.
Methane production (CH4, mmol / L) significantly increased but also without a clear
trend either with tested roughages or enzyme levels used.
Increases in in vitro cumulative gas production from treated rice straw, sugar-cane
tops and wheat straw were detected especially as the incubation time increased, no significant
differences in in vitro gas production for the different levels of enzymes used.