Influence of supplementary fibrolytic enzymes on the fermentation of corn and grass silages by mixed ruminal microorganisms in vitro

R. J. Wallace, S. J. Wallace, N. McKain, V. L. Nsereko, G. F. Hartnell

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Abstract

This study was done to determine the effectiveness of supplementary enzymes at increasing the fiber digestion by ruminal microorganisms and to assess whether enzyme activity limits the rate of fiber digestion in ruminal digesta. In vitro comparisons of enzyme activities in two feed enzyme preparations (A and B) with enzyme activities extracted from ruminal fluid indicated that the addition of fibrolytic enzymes at the application rates recommended by the manufacturers would not be expected to increase significantly glycanase and polysaccharidase activities in ruminal fluid. Preparations A and B both increased (P <0.001) the rate of gas production from freeze-dried corn and grass silages in in vitro incubations with ruminal fluid, but only at concentrations much higher than recommended application rates. Autoclaved controls had little or no effect. Ultrafiltration of enzyme B indicated that most stimulation was due to components >100 kDa, which is consistent with the cause of the stimulation being enzyme activity. Fibrolytic enzymes from other sources were also able to stimulate gas production: increased rates of gas production were observed in seven out of eight combinations of "cellulase" and corn or grass silage (P <0.05). The comparison of glycanase and polysaccharidase activities with gas-stimulatory activity in the different enzyme preparations indicated that the highest correlation was between increased gas production and enzyme activity against microgranular cellulose (P <0.05). In a wider range of fibrolytic enzyme preparations, those with endo-(beta-1,4)- or exo-(beta-1,4)-xylanase activity equal to that of preparation A did not produce similar increased rates of fermentation of corn silage when glucanase activity was low (P > 0.05). In contrast, preparations with glucanase activity similar to enzyme A gave at least as great (P <0.05) an improvement in gas production than enzyme A, irrespective of xylanase activity. It was concluded that enzyme activity, probably a type of endo-(beta-1,4)-glucanase activity, limits the rate of fermentation of corn and grass silage in the rumen. Enzyme supplements of the type used in these experiments are unlikely to possess sufficient activity to overcome this limitation by direct application to ruminal digesta, implying that treatment of the ration prefeeding will be key to harnessing the potential of exogenous fibrolytic enzymes in ruminant nutrition
Original languageEnglish
Pages (from-to)1905-1916
Number of pages12
JournalJournal of Animal Science
Volume79
Issue number7
Publication statusPublished - Jul 2001

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rumen microorganisms
Silage
grass silage
Poaceae
corn silage
Fermentation
Zea mays
fermentation
Enzymes
enzymes
gas production (biological)
enzyme activity
digesta
rumen fluids
endo-1,4-beta-glucanase
Cellulase
Gases
ruminant nutrition
In Vitro Techniques
xylanases

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Influence of supplementary fibrolytic enzymes on the fermentation of corn and grass silages by mixed ruminal microorganisms in vitro. / Wallace, R. J.; Wallace, S. J.; McKain, N.; Nsereko, V. L.; Hartnell, G. F.

In: Journal of Animal Science, Vol. 79, No. 7, 07.2001, p. 1905-1916.

Research output: Contribution to journalArticle

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T1 - Influence of supplementary fibrolytic enzymes on the fermentation of corn and grass silages by mixed ruminal microorganisms in vitro

AU - Wallace, R. J.

AU - Wallace, S. J.

AU - McKain, N.

AU - Nsereko, V. L.

AU - Hartnell, G. F.

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N2 - This study was done to determine the effectiveness of supplementary enzymes at increasing the fiber digestion by ruminal microorganisms and to assess whether enzyme activity limits the rate of fiber digestion in ruminal digesta. In vitro comparisons of enzyme activities in two feed enzyme preparations (A and B) with enzyme activities extracted from ruminal fluid indicated that the addition of fibrolytic enzymes at the application rates recommended by the manufacturers would not be expected to increase significantly glycanase and polysaccharidase activities in ruminal fluid. Preparations A and B both increased (P <0.001) the rate of gas production from freeze-dried corn and grass silages in in vitro incubations with ruminal fluid, but only at concentrations much higher than recommended application rates. Autoclaved controls had little or no effect. Ultrafiltration of enzyme B indicated that most stimulation was due to components >100 kDa, which is consistent with the cause of the stimulation being enzyme activity. Fibrolytic enzymes from other sources were also able to stimulate gas production: increased rates of gas production were observed in seven out of eight combinations of "cellulase" and corn or grass silage (P <0.05). The comparison of glycanase and polysaccharidase activities with gas-stimulatory activity in the different enzyme preparations indicated that the highest correlation was between increased gas production and enzyme activity against microgranular cellulose (P <0.05). In a wider range of fibrolytic enzyme preparations, those with endo-(beta-1,4)- or exo-(beta-1,4)-xylanase activity equal to that of preparation A did not produce similar increased rates of fermentation of corn silage when glucanase activity was low (P > 0.05). In contrast, preparations with glucanase activity similar to enzyme A gave at least as great (P <0.05) an improvement in gas production than enzyme A, irrespective of xylanase activity. It was concluded that enzyme activity, probably a type of endo-(beta-1,4)-glucanase activity, limits the rate of fermentation of corn and grass silage in the rumen. Enzyme supplements of the type used in these experiments are unlikely to possess sufficient activity to overcome this limitation by direct application to ruminal digesta, implying that treatment of the ration prefeeding will be key to harnessing the potential of exogenous fibrolytic enzymes in ruminant nutrition

AB - This study was done to determine the effectiveness of supplementary enzymes at increasing the fiber digestion by ruminal microorganisms and to assess whether enzyme activity limits the rate of fiber digestion in ruminal digesta. In vitro comparisons of enzyme activities in two feed enzyme preparations (A and B) with enzyme activities extracted from ruminal fluid indicated that the addition of fibrolytic enzymes at the application rates recommended by the manufacturers would not be expected to increase significantly glycanase and polysaccharidase activities in ruminal fluid. Preparations A and B both increased (P <0.001) the rate of gas production from freeze-dried corn and grass silages in in vitro incubations with ruminal fluid, but only at concentrations much higher than recommended application rates. Autoclaved controls had little or no effect. Ultrafiltration of enzyme B indicated that most stimulation was due to components >100 kDa, which is consistent with the cause of the stimulation being enzyme activity. Fibrolytic enzymes from other sources were also able to stimulate gas production: increased rates of gas production were observed in seven out of eight combinations of "cellulase" and corn or grass silage (P <0.05). The comparison of glycanase and polysaccharidase activities with gas-stimulatory activity in the different enzyme preparations indicated that the highest correlation was between increased gas production and enzyme activity against microgranular cellulose (P <0.05). In a wider range of fibrolytic enzyme preparations, those with endo-(beta-1,4)- or exo-(beta-1,4)-xylanase activity equal to that of preparation A did not produce similar increased rates of fermentation of corn silage when glucanase activity was low (P > 0.05). In contrast, preparations with glucanase activity similar to enzyme A gave at least as great (P <0.05) an improvement in gas production than enzyme A, irrespective of xylanase activity. It was concluded that enzyme activity, probably a type of endo-(beta-1,4)-glucanase activity, limits the rate of fermentation of corn and grass silage in the rumen. Enzyme supplements of the type used in these experiments are unlikely to possess sufficient activity to overcome this limitation by direct application to ruminal digesta, implying that treatment of the ration prefeeding will be key to harnessing the potential of exogenous fibrolytic enzymes in ruminant nutrition

M3 - Article

VL - 79

SP - 1905

EP - 1916

JO - Journal of Animal Science

JF - Journal of Animal Science

SN - 0021-8812

IS - 7

ER -