HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: jas.2006-318v1 85/8/1962    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Giraldo, L. A. Articles by Carro, M. D. Search for Related Content PubMed PubMed Citation Articles by Giraldo, L. A. Articles by Carro, M. D.

Effects of exogenous cellulase supplementation on microbial growth and ruminal fermentation of a high-forage diet in Rusitec fermenters¹

L. A. Giraldo^*,, M. L. Tejido^*, M. J. Ranilla^* and M. D. Carro^*,2

^* Departamento de Producción Animal, Universidad de León, 24071, Spain; and Universidad Nacional de Colombia, Sede Medellín, Facultad de Ciencias Agropecuarias, 1027, Medellín, Colombia

² Corresponding author: mdcart{at}unileon.es

Two incubation runs were carried out with a Rusitec system to investigate the effects of 2 exogenous pure cellulases on ruminal microbial growth and fermentation of a 70:30 grass hay:concentrate (DM basis) substrate. The substrate was sprayed with buffer (control; pH = 6.5), a cellulase from Trichoderma longibrachiatum (TRI), a cellulase from Aspergillus niger (ASP), or a 1:1 mixture of both cellulases (MIX) 24 h before being placed in the fermenters. Enzymes were applied at a rate of 30 endoglucanase units/g of substrate DM. Treating the substrate with enzymes reduced substrate NDF and ADF content (P < 0.001 to P = 0.002) and increased DM, NDF, and ADF disappearance after 6 and 24 h of incubation (P < 0.001 to P = 0.004) but not after 48 h of incubation. Daily VFA production was increased (P = 0.004) by 15, 9, and 15% for TRI, ASP, and MIX, respectively, with half of the increase being due to production of acetate. All enzyme treatments augmented (P = 0.009) methane production, but none of them altered the methane:VFA ratio (P = 0.70). There were no differences (P = 0.80) among treatments in the daily flow of solid-associated microorganisms, as measured using ¹⁵N as a microbial marker. Although the TRI and MIX treatments increased (P < 0.05) the daily flow of liquid-associated microorganisms and the proportion of microbial N in the solid residue after 48 h of incubation, no effects were observed (P = 0.92 and P = 0.95, respectively) for the ASP treatment. The results show that the TRI and MIX treatments enhanced in vitro fermentation by increasing substrate fiber degradation, VFA production, and ruminal microbial growth. The lack of differences between TRI and MIX in most of the measured variables indicates that treating the substrate with a mixture of both cellulases did not further improve the effects of the TRI treatment.

Key Words: cellulase • ruminal fermentation • microbial protein synthesis • Rusitec

This article has been cited by other articles:

				L. A. Giraldo, M. L. Tejido, M. J. Ranilla, S. Ramos, and M. D. Carro Influence of direct-fed fibrolytic enzymes on diet digestibility and ruminal activity in sheep fed a grass hay-based diet J Anim Sci, July 1, 2008; 86(7): 1617 - 1623. [Abstract] [Full Text] [PDF]