Resumen:
The effects of the exogenous fibrolytic enzyme (ENZ) commercial preparation Dyadic® xylanase
PLUS (Dyadic International, Inc., Jupiter, USA), containing endo-1,4-β-d-xylanase, on ruminal fermentation of
maize stover, oat straw, and sugarcane bagasse were examined using the in vitro gas production (GP) technique.
The ENZ commercial preparation was added at 0 (control), 60 (low), 120 (medium), and 240 (high) μg/g dry
matter of substrate, and at two times of application (direct addition just before fermentation or with a 72-h
pre-incubation before fermentation). Ruminal GP volumes were recorded at 2, 4, 6, 8, 10, 12, 14, 24, and 48 h
of incubation, and substrate degradability and concentration of fermentation end-products (volatile fatty acids,
ammonia, methane) in the cultures were determined at 48 h of incubation. Increased (P < 0.05) GP volume
was observed in fibrous feeds treated with ENZ compared with untreated substrates. The pre-incubation vs the
direct addition of ENZ resulted in greater GP volume (P < 0.05) with the three tested feeds. Enzyme addition
decreased (P < 0.05) rumen pH compared to control when maize stover and sugarcane bagasse were incubated.
Ammonia-N and total volatile fatty acids (VFA) were not affected (P > 0.05) by ENZ application in maize stover
and oat straw. However, total and individual VFA concentrations, and CH4 and CO2 volumes were greater (P <
0.05) when sugarcane bagasse was incubated with 240 μg ENZ/g (P < 0.05). It can be concluded that the application
of endo-1,4-β-d-xylanase enhances rumen fermentation of roughages, although the magnitude of the
effects depends on the fibrous substrate fermented, the time of application, and the amount of enzyme added.
Descripción:
These by-products could be used as animal feedstuffs,
but their use is limited by their high fibre
content, which invariably lowers the efficiency of
digestive utilization (Khattab et al. 2013; Kholif et
al. 2014). Fibrous feeds are characterized by high
lignocellulose content, low crude protein (CP) content,
poor palatability, and low nutrient digestibility
(Kholif et al. 2014; Togtokhbayar et al. 2015).
The structural carbohydrates of the fibre are less
digestible than other nutrients, and the cell wall
(mainly the lignin) may be a physical barrier for
the bacterial attachment and the access of ruminal
enzymes resulting in limited ruminal degradability
(Karunanandaa et al. 1995)