A strong Castleford team scored eight unanswered tries to race into a 48-0 lead at the break.
But the Dons could take plenty of heart from a second half which saw both sides score three converted tries.
Misi Taulapapa, Zac Braham and Tom Halliday touched down for Doncaster with Connor Robinson adding the extras.
Doncaster host Thornhill Trojans in the second round of the Betfred Challenge Cup on Sunday.
Dons: Taulapapa, Halliday, Smeaton, Storey, Corrion, Johnston, Robinson, Fella, Burns, Braham, Ollett-Hobson, York, Peterson. Interchanges: Sanderson, Whitmore, Seaman, Ruan, Roberts.
Castleford: Evalds, Olpherts, Fonua, Mamo, Faraimo, Trueman, Richardson, Lawler, Robb, Massey, Blair, Edwards, Westerman. Interchanges: Turner, Marris, Sutcliffe, Griffin, Hepi, Clare, Smith, Morley, Matagi, Vasuitoga, Martin, Hall, Brennan-Jones, Ransome, Qareqare, Sadler, Carter, Collins.
Misi Taulapapa, Zac Braham and Tom Halliday touched down for Doncaster with Connor Robinson adding the extras.
![Dave Peterson tries to find a gap in the Castleford defence.](https://www.chichester.co.uk/webimg/b25lY21zOjJmMTdlMzA4LTgxMDktNGFjNC1hNzdiLWE4NzMzNTg4MWIwZTo0NTJlNDJhNi1hMGYxLTQ3ODgtYTRhMi05NmVhOWJhNDkzMWY=.jpg?crop=3:2&width=640)
5. On the front foot
Dave Peterson tries to find a gap in the Castleford defence. Photo: Andrew Roe/AHPIX LTD
![Zac Braham tries to get over the try line.](https://www.chichester.co.uk/webimg/b25lY21zOmM2MjA4NzFjLTM4ZDgtNGRhZS05ZDRlLTYyOGVmMGU2MzRiMDplNjA4MzVlMS01MzcxLTQwNTMtYTkyMS00NzY3MzQ4NDVjNTM=.jpg?crop=3:2&width=640)
6. Touching distance
Zac Braham tries to get over the try line. Photo: Andrew Roe/AHPIX LTD
![Zac Braham, who scored one of Doncaster's three tries, stretches for the line.](https://www.chichester.co.uk/webimg/b25lY21zOjQ2NGJiMjcxLTU4YTQtNDAwOC1hM2YzLWQ1YTU5NWYzNmE0MDpjMGFiNmE3MS1mMWE5LTQ2ZTMtODEyYi00MzNiNjY0YjY3ZDc=.jpg?crop=3:2&width=640)
7. Reaching out
Zac Braham, who scored one of Doncaster's three tries, stretches for the line. Photo: Andrew Roe/AHPIX LTD
![Jack Sanderson makes some ground with ball in hand.](https://www.chichester.co.uk/webimg/b25lY21zOmIwZmY2ZGM0LTZmNzktNDgwMC04ZmNiLTI3MjkwMTljMWEyYzo2YzRiNDIxYi04ZTJjLTQ3ZGQtODg4NC1jMjVjNDVjYjQ1MzM=.jpg?crop=3:2&width=640)
8. Ball in hand
Jack Sanderson makes some ground with ball in hand. Photo: Andrew Roe/AHPIX LTD