Byrd pumped in 22 points and grabbed eight boards while Johnson supplied 16 and six for the Boilermakers (14-15, 7-9 Big Ten), who used a dominating second half to notch the win.
Sandi Marcius also reached double figures with 10 points for Purdue.
The Badgers (20-9, 11-5), meanwhile, saw their three-game winning streak snapped despite 13 points and eight rebounds from Jared Berggren.
Ryan Evans contributed 10 points and seven boards in the loss.
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