Minolta MD mount is a bayonet lens mount used on the last generation manual focus Minolta cameras. The mount incorporates meter-coupling and automatic diaphragm, and is backwards compatible with Minolta MC lenses. The MD lenses can be used in shutter priority mode with Minolta XD-7, Minolta XD-5, and Minolta X-700. You could get an MD to A-mount converter. They are out there and available (usually from someone on ebay)
Now, when it comes to the new SONY DSLRs ... they only directly use the A-mount or AF lenses.
There are many of these out there, also. You need to realize that that older zoom lenses are not going to shoot as sharp on a DSLR as they do on an 35mm-film SLR camera.
The "Primes" (fixed focal length lenses, on the other hand, will shoot very sharp and will deliver a good image. Lens like the Minolta AF 50mm f/1.7
AF 50mm f/1.4
Note the five gold contacts.
and the Minolta AF 28mm f/2.8 are not very expensive and should be pretty easy to buy.
I hope this helps