23 elephants in total that is, not all of them live in the main reserve as they are split into at least 4 different groups (of which 1 African group). They do have the largest amount of elephants, that's been the case now for a few years I recall. Wether they have the biggest herd is another more doubtfull case.
Yes, they have the biggest herd of asian elephants in Europe. Their elephants are divided into these groups:
1. African elephants- Suzy, Chitana
2. Older asian elephant cows- Jana and Praya
3. Sayang's family- Sayang, Saphira, Sitara, Thambi, Ravi
4. Mala and Khaing Hnin Hnin's family- leader cow Mala, Khaing Hnin Hnin, Aye Chan May, Farina, Soraya, Amithi, Malay, Nang Faa, Ta Wan, Malee, Luna
Bulls Chamundi and Po Chin live separately or with different herds.
The largest herd is therefore the fourth herd. Leipzig or Cologne compete a bit, but they don't have as many elephants in one herd.