Rovers led 1-0 at the break after Hird netted past reserve keeper Jamie Annerson from John Oster's centre.
Hayter headed a second before Barrow trialist Walker slotted a third with Hayter completing the scoring with ten minutes left.
The Millers missed several chances with both Taylor's, Jason and Ryan, going close. Pablo Mills hit the crossbar late on with a mishit cross while Kevin Ellison was guilty of wasting two further opportunities.
"I've mixed things up today but we've got another game on Tuesday night, where I'll be looking to play a different side. We've then got a further game on Wednesday night where I'll be looking at the players who don't get a game on Tuesday.
"I'm not too disappointed - of course we didn't want to lose 4-0 - but at the end of the day it doesn't make any difference.It was a lesson for us today, and we certainly have to be better than we were today. We haven't turned up and nailed the performance like we did on Wednesday against Forest.
"I made a few changes from that side and clearly it hasn't worked, but everyone worked hard."
No sign of Reuben Reid once again who appears Blackpool bound, whilst Andy Liddell featured before dashing to Manchester to play in the North West masters for Oldham this evening.
Millers tream: Annerson, Lynch, Sharps (Nicholas 75), Fenton, Green (Ellison 52), Mills, Harrison, Cummins (J Taylor 45), Brogan, Law (Liddell 58), R Taylor (Warne 75).