I am not aware that government bonds are traded on central exchanges, but most of the business is done OTC or through private clearing partnerships. Eurex - the exchange where Bund and Bobl futures trade - has set up a trading and clearing platform for bond trading.
Trading times are as per document below. Deduct 7 hours to translate to US Central Time.
Information on the German Government Bond Market. Source is SIFMA, document attached.
There are three (3) Platforms operating on the German Government Bond market: Eurex Bonds, ICAP/Brokertec and MTS Deutschland
The German Finance Agency does not require the members of its Bund Issues Auction Group to settle the transactions on a specific CSD.
In Germany, LCH Clearnet SA is available as a central counterparty on ICAP/Brokertec where participants have to use it and MTS Deutschland for which itís an option offered to the participants. On Eurex Bonds however the participants may use Eurex Clearing as a CCP and Clearstream Frankfurt, Clearstream Luxembourg or Euroclear Bank for the settlement of the trades. ICAP/Brokertec and MTS Deutschland both as well offer settlement facilities on the domestic CSD, Clearstream Frankfurt, and the two (2) ICSDs, Clearstream Luxembourg and Euroclear Bank.
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