From your description of the Alexandria Zoo it sounds like they hardly have any of the animals that they have enclosures for (giraffes, elephants, etc.). Does the Giza Zoo still have most of the animals on the map here or has it become depopulated also?
Actually most of the animals on the map are present. I'm not sure if the African elephant is still about but otherwise everything on our route was as signed. The majority of the animals in Alexandria Zoo and the other government-owned zoos come from Giza; so unless they import or breed surplus animals, the smaller zoos don't get them passed down.
How long would it take a first-time visitor to tour the zoo? The map appears to be fairly extensive but zoo maps are often deceiving...
It is a large and densely-packed zoo. I'm not too sure about the first-time visit, because most animals can be fed by visitors and sometimes visitors can enter off-show areas for a price - which adds to duration of the visit (even though you might choose not to feed animals, keepers can better position the animals for photography for a fee. This year especially I found people struggling with the idea that I was photographing their animals without paying them for something). There's also a lot of duplication, although there tends to be a little variety (e.g. two lion houses but one also holds a white lion and the other cheetah. I'd say it would need at least 4-5 hours to see properly, but it can easily be a full day zoo.