How about:
=MID(TEXT(A1," 0/0"),FIND("/",TEXT(A1," 0/0"))+1,999)&":"&TRIM(MID(TEXT(A1," 0/0"),1,FIND("/",TEXT(A1," 0/0"))-1))
assuming the 0.25 is in cell A1.
Or even:
=TRIM(MID(TEXT(A1," ??/??"),FIND("/",TEXT(A1," ??/??"))+1,999))&":"&TRIM(MID(TEXT(A1," ??/??"),1,FIND("/",TEXT(A1," ??/??"))-1))
to cope with a wider range of numbers.