silent at the beginning when the file is export as mp3

Good day, everyone!

I’m using Audacity 2.0.3/Windows 7, and my problem is that when I want to seperate some part of audio, (part when audio is looping), Audacity add silent on the begining of track and offset it in time. It looks like this:

I selected loop part and exported as mp3. After that I open again in Audacity.

How can I save track without this silent?

Thank you very much for all your help.
Greetings!

It’s not Audacity adding silence, it’s a limitation of the MP3 format. Encoder / decoder overall delay is not defined, which means there is no official provision for gapless playback MP3 - Wikipedia

Use a different format, such as WAV, AIFF, FLAC or OGG Vorbis.