Hanover Zoo

You can find the Hanover Zoo in the Zoo quarter of the city Hanover.

It is one of the oldest zoos in Germany and was founded in 1865. From 1990 onwards the zoo was converted into a more animal friendly place. 

You can find seven theme worlds in the zoo with different animals in each of them. There are Zambezi, which shows the African Savannah, the Gorilla Mountain, Yukon Bay, which leads you into a Canadian gold town, the Jungle Palace, the Australian Outback, Mullewap and Meyer's Farm. During the winter time there is also the Winter Zoo and some parts of the zoo are decorated around Christmas.

The entry fees are not that cheap but you can easily stay the whole day and take your time to see every corner of the zoo. When you're visiting with children it's maybe better when you take something to eat and to drink with you because food can be expansive as well.

One thing you have to do is to take the boat in Zambezi and see the African animals from the boat which gives you a different perspective. There are also feedings of different animals which you can watch.

In Hanover Zoo everyone can find a favourite animal.

You can find more info here:

Wikipedia

Erlebnis Zoo Hannover

Wisentgehege

The Wisentgehege is a deer park in northern Germany where you can watch European animals. It's open all year round.

Picture:
Wolves in the Wisentgehege

First, the Wisentgehege was only for breeding European bisons and that's where it got it's name from. Now you can find around 100 different animal species there including Przewalski’s horses, wolverines, elks and different deer species.
One of the main purposes of the deer park is the conservation breeding of endangered animals but it's also a shelter for injured birds of prey.

The deer park is situated in a woody area with old trees and nice paths to walk on. Some of the animals are in enclosures but some, like the deer, have a wide space almost like in the wild. During the day there are different "shows" the visitors can watch. You can see feedings of different animals or an air show with the birds of prey. There is a lot to learn in the Wisentgehege, not only about the animals but about nature in general, too.
They are always building new enclosures for the animals and try to keep them in a natural way. You can spend a day in the Wisentgehge and take a picnic along with you if you want. There are many nice places where you can sit and eat but there is also a restaurant when you don't want to take food along.
The Wisentgehege is a great place to watch European animals in a nature like environment and to spend a nice day with your family.

If you want to read more, you can have a look here:
http://www.wisentgehege-springe.de/ (German)
Wikipedia (German)