Rob Jones and Chris Brown find the net in either half for Rovers in a game which only went ahead after a massive snow-clearing operation.
And Slade said: "It might have been better for us had it been off.
"We had a cup game with extra-time during the week and I had to make changes to freshen things up a little bit.
"The pitch was a little bit tricky in places but there are no excuses. It was perfectly playable and they played on it much better than us.
"Doncaster are the benchmark for this division. They are a good side but, having said that, we were only behind by a goal at the interval to a set-play.
"The second goal we tried to play for offside and it didn't come off and we have to learn from our mistakes.
"Both goals we conceded were disappointing and we have to learn from Doncaster in terms of what it takes to be successful in this league."