Pups are a few hours old.One very large pup had a long tiring birth. Seems quite a strong pup, wriggles, squeals when picked up, seems normal but just very reluctant to nurse even when I try and hold her on. Vet did not seem too worried and put it down to being tired. Is this feasible or should I be worried. She will suck finger but not at allkeen on latching onto teat

She may not be latching on properly,

Try expressing a little milk from a teat and when it's nice and milky try getting her to latch on.  Make sure the teat goes right in her mouth, then stroke under her chin and throat.  If she's hungry that should get her feeding ;)

Of course, it could be that she gets plenty in less time than the smaller pups ;)  Is she fussing and trying to feed or really content?  has she been weighed?  The way to tell if she's getting enough is to weigh daily and see the difference ;) 

I had a tiny pup recently that wouldn't latch on. She used to pump with her head and legs but had nothing in her mouth. An old very experienced breeder said to put some of my saliva on the mum's teat. I did it and she went straight on. Funny, but it worked!

She does latch on but not very strongly, doesnt gulp like the others. She has lost about 3/4 of an ounce today but I know sometimes they can in first 24 hours. Its almost as if she has no idea how to latch on herself. I am letting one of the stronger pups start the milk then putting her on. At what point does one think of bottle feeding...not that I have ever tried this. Its almost as if she is a bit slow on the uptake.....

My last litter was a bit thick about latching on, they either didn't seem to think of opening their mouths, or they opened them, got the teat in the mouth, then forget to close again before trying to suckle. They got the idea in a day or two though!