geepers your post does once again make me realise hw good my hosptial was and how lucky we were in this respect.
In respect of amouns/colostrum etc. In my case DS had my bm for the first few hours but then yes the staff calculated how much he should take, and regularly checked his blood sugar. His first feed was 0.5 ml mind you, increasing by 0.5 ml per hour up to the figue they work to (75 ml per kilo then 150 ml per kilo per day) obviously it took some time to get to those figures. As I said before my milk came in, but there is a bliss leaflet which talks about trying to express colostrum and the mother and father chasing round the mothers breast with a syringe to get one drop then perhaps 2 drops after the birth for a few days and that's the truth for many mums, as it does often take longer for the milk to come in if your body is in shock or not expecting labour.
I recall my first few feeds were stored in tiny syringes in the nicu fridge, and that was stressful enough.
On the weight thing, yes the tests are tougher. My DS was 1360 g when he was born (exactly 3lb) and the docs told me that while I would hate them for saying this, he was a very good size for gestation. However even on my milk he lost weight and went down to 1060 grams in a week which is more than the 10% which would be of concern in a term baby, and he didn't have the weight to lose. My ds dietician was fine with this, but he was weighed daily to keep an eye on how much he lost and his blood sugar was checked to keep an eye on him. he then started gaining, but had he not done they would probably have had to try something else (tpn before formula I suspect).
There was a phase later when he wouldn't come off his hot cot and couldn't mainatain his temperature on his own and he lost weight again(down from 2000g to 1907 g) That was just before discharge and I was speaking to the consultants daily about how long we had before he would need supplementing with nutriprem. Its a discussion which took place daily!