The BMD-300, BMD-301, and BMD-350 support the ANT+ protocol with the SoftDevices S212 (ANT+ only) and S332 (BLE and ANT+). These SoftDevices are licensed from and available through Garmin / Dynastream. Information about these SoftDevices and the nRF52, which is in our BMD-300 Series, can be found here.
The BMD-330 does not support ANT+.
The BMD-340 will support ANT+ with a future release of the S340 SoftDevice, expected out in 1H 2019.
Nordic Semiconductor's SDK also includes examples for ANT+ and ANT+ with BLE. These examples rely on the SoftDevices noted above.