The aim of this study was to evaluate the chemical
composition of five foliages, and the effect of adding
PEG during incubation on in vitro gas production
(GP), metabolizable energy (ME), partitioning factor
(PF24h), in vitro organic matter digestibility (OMD),
short chain fatty acids (SCFA) and microbial biomass
production (MBP) as tools to detect the adverse effect
of tannins in the foliage of non-leguminous trees.The objective of the current study was to
evaluate the chemical composition and the in vitro gas
production (GP) of some non-leguminous forage trees
in presence or absence of polyethylene glycol (PEG).
Guazuma ulmifolia, Crescentia alata, Ficus glabrata,
Ficus cotinifolia, Spondias purpurea, Mangifera
indica, Licania arborea, Simira mexicana were collected
during the rainy season, in the Bejucos locality,
State of Mexico. Metabolizable energy (ME), partitioning
factor (PF24h), in vitro organic matter digestibility
(OMD), short chain fatty acids (SCFA) and
microbial biomass production (MBP) were estimated
as tools to detect the adverse effects of tannins in tree
foliage. The chemical composition data were analyzed
in a random design, and the in vitro digestion
parameters on a randomized design with 8 9 2
factorial arrangement. Chemical composition showed
a wide variation (P\0.05) between species. The use
of PEG increased (P\0.05) GP from the foliage of S.
purpurea, L. arborea, F. glabrata and G. ulmifolia,
showing activity of total phenolics and condensed
tannins. Similarly, ME (5.9 MJ kg-1 DM), OMD
(354.5 g kg-1 DM) and SCFA (2.3 mol/150 mL)
increased (P\0.05); it was higher for S. purpurea,
because of the PEG addition effect. The PF24h and
MBP were different between species (P\0.05), and
decreased due to PEG addition (P\0.05); the species
with lower production was S. purpurea. It could be
concluded that S. purpurea and F. cotinifolia represent
important sources of fodder for livestock in the south
region of Mexico