Resumen:
To assess the nutritional value of the leaf of four browse trees (Chorisia speciosa, Cassia fistula,
Schinus molle, Eucalyptus camaldulensis), that are grown in semi-arid regions of northern Egypt, this
study evaluated effects of incorporation of polyethylene glycol (PEG) on their nutritional value. In vitro
gas production after 24 h of fermentation (IVGP24), volatile fatty acids (VFA), ammonia concentrations
and microbial protein synthesis were determined, and in vitro organic matter digestibility (IVOMD)
and metabolizable energy (ME) were estimated. The IVGP24, VFA and ammonia N concentrations
varied (P<0.001) among browse species, with the IVGP24 and VFA highest (P<0.001) for C. speciosa,
lowest (P<0.001) for E. camaldulensis, and intermediate for C. fistula and S. molle. C. speciosa had the
highest (P<0.05) IVOMD, microbial protein synthesis, IVOMD and ME, while these measurements
were lowest in E. camaldulensis and intermediate in the other browse leaves. In general, C. speciosa has the highest potential as a ruminant feed, the lowest being E. camaldulensis and S. molle, with C. fistula
intermediate. Addition of PEG increased (P<0.001) IVGP24, VFA and ammonia N concentrations, as
well as gas production (P<0.05). The highest overall improvement was for C. speciosa, intermediate
for E. camaldulensis, and lowest for C. fistula and S. molle. Addition of PEG reduced (P<0.01) the
amount and efficiency of microbial protein synthesis, and increased (P<0.001) IVOMD and ME in
all leaves. The extent of the benefit of PEG on overall nutritive value varied somewhat by browse,
with E. camaldulensis judged to have the largest overall improvement, C. fistula the lowest with C.
speciosa and S. molle intermediate. However PEG addition did not change overall nutritive ranking
of these browse leaves.
