my bitch is 36 days pregnant, when is it best to start to change her over to puppy food? i was told puppy food has better ingredients.

For me - I did not change the food when pregnant, just upped the ammout. I only fed her on puppy food when she was feeding the pups.

Everyone has different approaches on this, puppy food has alot more fat in it, and alot of that is not good for the mother or puppies inside her and can make delivering them more difficalt.

I generally put them onto puppy food at about 5 weeks once I think the bitch is in whelp. I do not up food prior to whelping, as you  can end up with very large puppies which the dog cannot deliver.I only up the food after the dog has whelped.

I change to puppy food at 5 weeks, giving extra if they are asking for more.  In fairness, most don't eat an awful lot towards the end, when they look all packed out with pups.  I find giving smaller portions more frequently is better.  Once whelped, they stay on puppy food until pups are weaned.  Obviously fed ad lib once whelped.

you have scared me now (large puppies) :-)