New user, but have been stalking for a while.
Got my first orphan/cade Suffolk X lambs 3 days ago, just 2 but it’s a good starting point for a novice.
They were born to a yearling who had twins and the farm policy is to take away one lamb so as not to rundown the yearling.  Traumatic time for 4 day old lambs, plus car journey and new surroundings.  Little wonder they wouldn’t take to the bottle.  A lot of scanning/searches of the forum for any help, and I found some good suggestions which I tried.  Three days on and they’re sucking the bottles inside out to get at it!!  What seemed to crack it for me was a change of bottle to a 500ml anti vacuum bottle with a smaller teat that ended in a ‘spike’ that I could snip the end off to get the right size hole.  Plus rather than guessing the temp of the milk I used a thermometer, with 40/42 being the optimum couldn’t resist temp.  Probably dropped a couple of degrees before it gets to the lambs though.
So just a big thanks to the regular contributors for their knowledge, you got me over the first hurdle.