We investigate the role of orbital degeneracy in the double-exchange model.
In the J(H)--> infinity limit, an effective generalized "Hubbard" model in
corporating orbital pseudospin degrees of freedom is derived. The model pos
sesses an exact solution in one and in infinite dimensions. In one-dimensio
n, the metallic phase off ''half-filling" is a Luttinger liquid with pseudo
spin-charge separation. Using the d=infinity solution for our effective mod
el, we show how many experimental observations for the well-doped (x simila
r or equal to0.3) three-dimensional manganites La1-xSrxMnO3 can be qualitat
ively explained by invoking the role of orbital degeneracy in the double ex
change model.