are you using (by any chance) the bottle that come with Royal Canin baby milk??? if so, it's because the bottle is hard (non squeezable) plastic. I hate these bottles. I prefer the ones that you can usually buy loose in pet shops (i.e. they're not sold with milk, they're sold on their own) and they are like the old fashioned Fairy Liquid bottles... you can actually squeeze the milk out of them (although of course you should never squeeze milk into a kittens mouth). The Royal Canin bottles (or any of those hard plastic bottles) depend on the kittens having a well developed sucking reflex, and wanting to drink from a bottle.
is that the one that comes in the white tin with dogs and cats on the front of the tin?? Sherley's brand I think it is?? if so... it's not bad in coffee... but hellish with cornflakes
I don't like this particular milk (it often cristalizes and sticks in the teet)... I also don't have good results with it (a lot of kittens don't seem to like it, and also regards weight gain... not great either). But if you're using it for "topping up" feeds (i.e mum is still feeding them but not quite enough) then it should be okay. Personally (again though... just my own opinion) I wouldn;t use it for an orphaned/rejected kitten that was depending solely on me for it's nutrition.
sorry, I have just re-read your post and realised that your using a pin to prick a hole in the teet. I use (very small) nail scissors with points on the end. And with the very small kittens I squash the teet flat and take of the tiniest sliver of rubber... and with the same scissors, as they get bigger and need/can drink more... I make the hole in the teet bigger with these same scissors (I kinda stab the point of the scissors into the existing hole in the teet). I used to use a thick darning needle with a sharp point on it, but I lost that needle and never got around to replacing it. I peronally feel a pin hole would be too small??? When the holes are too small on teets, I always find that they suck too much air and not enough milk. But everone has their own technique with bottle feeding, and what works for me might not work for the next person. Also I feel too small holes are uselss when kittens don't have a well developed suck reflex.
I know lactol kitten milk can be left in the fridge for 24 hours after its made up... but as BBM says... all other milk brands I have used must be made and used up more or less immediately.... and if you do use lactol and refrigerate it... I found it verrrry tricky to get it warmed up properly. I poured it into their bottles and popped them into a cup of boiling water... but they'd get too hot, lol, so then I'd have to pop them in to a cup of cold water. So even if I was going to use lactol again, I personally feel it's easier to make up and use as needed.
Hopefully though mummy cat has stepped up to the plate and you won't need to bottle feed afterall. Murphy's law, lol, if you don't have the supplies at hand - they need bottle feeding, when you do have everything you need at hand - they don't need it. Go figure. Bets of luck with your new little family.
I use a wool needle to make holes in the teats i use, if its very tough i heat the needle first before pushing it through. Wool needles are fairly blunt but fairly wide. I would go with tje's suggestion though!
As for the milk... unless you suddenly have 6 ravenous 4/5 week old orphaned kittens on your hands its not worth making up before hand. To make it up before hand and heat it properly you need a fairly large amount (otherwise you get the issues tje described), and the only way you would be going through it in such quantities would be a large litter of handrearing babies.
Keep us posted, but fingers crossed for now mum has got the idea!