Resumen:
This study was carried out to establish Saccharomyces cerevisiae, xylanase, and their mixture as environmentally
friendly feed additives that can reduce enteric biogas production. Rumen liquor was obtained
from two rumen cannulated Holstein steers, two rumen cannulated Creole goats and two rumen
cannulated Rambouillet sheep. The basal ration was supplemented (per g dry matter (DM)) with 2 mL
xylanase, 4 mg S. cerevisiae or a mixture of both additives. There was no interaction (P > 0.05) between
inoculum source and additive type. Inclusion of additives resulted in higher (P ¼ 0.045) asymptotic gas
production (GP) with sheep inoculum. Furthermore, higher (P < 0.05) GP rates with goat and sheep
inocula were noted with the additives. S. cerevisiae or/and xylanase decreased (P < 0.05) proportional
methane (CH4) irrespective of the inoculum source with an increase (P < 0.05) in carbon dioxide production.
Higher (P < 0.05) bacterial counts were observed with the inclusion of the additives. Metabolizable
energy and short fatty acid concentrations were higher (P < 0.05) when the additives were
supplemented to goat and sheep inocula. Additionally, inclusion of the additives resulted in higher
(P < 0.05) DM degradability in sheep and steer inocula and higher (P < 0.05) organic matter degradability
in goat and sheep inocula. S. cerevisiae, xylanase and their mixture did not affect total GP but altered the
proportion of the gases generated. Furthermore, CH4 production was reduced in the presence of the
additives. Thus, the additives can be utilized in an environmentally friendly and sustainable way to
reduce biogas emissions from livestock; thereby improving environmental conditions