| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
,3
,4
* Department of Agriculture, The University of Reading, Reading RG6 6AR United Kingdom;
and
FMS Division, Institute of Food Research, Norwich NR4 7UA United Kingdom; and
and
Agriculture and Agri-Food Canada, Research Centre, Lethbridge, AB, Canada T1J 4B1
3 Correspondence:
Agriculture and Agri-Food Canada, Research Centre, P.O. Box 3000, Lethbridge, AB, T1J 4B1 Canada (phone: +1-403-317 3427; fax: +1-403-317 2182; E-mail:
colombattod{at}agr.gc.ca).
A series of in vitro studies was conducted to determine the effects of adding a commercial enzyme product on the hydrolysis and fermentation of cellulose, xylan, and a mixture (1:1 wt/wt) of both. The enzyme product (Liquicell 2500, Specialty Enzymes and Biochemicals, Fresno, CA) was derived from Trichoderma reesei and contained mainly xylanase and cellulase activities. Addition of enzyme (0.5, 2.55 and 5.1 µL/g of DM) in the absence of ruminal fluid increased (P < 0.001) the release of reducing sugars from xylan and the mixture after 20 h of incubation at 20°C. Incubations with ruminal fluid showed that enzyme (0.5 and 2.55 µL/g of DM) increased (P < 0.05) the initial (up to 6 h) xylanase, endoglucanase, and ß-D-glucosidase activities in the liquid fraction by an average of 85%. Xylanase and endoglucanase activities in the solid fraction also were increased (P < 0.05) by enzyme addition, indicating an increase in fibrolytic activity due to ruminal microbes. Gas production over 96 h of incubation was determined using a gas pressure measurement technique. Incremental levels of enzyme increased (P < 0.05) the rate of gas production of all substrates, suggesting that fermentation of cellulose and xylan was enzyme-limited. However, adding the enzyme at levels higher than 2.55 µL/g of DM failed to further increase the rate of gas production, indicating that the maximal level of stimulation was already achieved at lower enzyme concentrations. It was concluded that enzymes enhanced the fermentation of cellulose and xylan by a combination of pre- and postincubation effects (i.e., an increase in the release of reducing sugars during the pretreatment phase and an increase in the hydrolytic activity of the liquid and solid fractions of the ruminal fluid), which was reflected in a higher rate of fermentation.
Key Words: Cellulose • Enzymes • Fermentation • Rumen • Xylan
This article has been cited by other articles:
|
|
 |
|
  L. A. Giraldo, M. L. Tejido, M. J. Ranilla, and M. D. Carro Effects of exogenous cellulase supplementation on microbial growth and ruminal fermentation of a high-forage diet in Rusitec fermenters J Anim Sci, August 1, 2007; 85(8): 1962 - 1970. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. B. Dean, A. T. Adesogan, N. Krueger, and R. C. Littell Effect of Fibrolytic Enzymes on the Fermentation Characteristics, Aerobic Stability, and Digestibility of Bermudagrass Silage J Dairy Sci, March 1, 2005; 88(3): 994 - 1003. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. Colombatto, G. Hervas, W. Z. Yang, and K. A. Beauchemin Effects of enzyme supplementation of a total mixed ration on microbial fermentation in continuous culture, maintained at high and low pH J Anim Sci, October 1, 2003; 81(10): 2617 - 2627. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
