Gerbil Mum had four pups but died today, only dad is left to look after them, they were born on christmas day.

looks like you will have to hand feed them. not sure what kind of milk but warm watered down cows milk could do as a start. Try using a cotton bud and dipping the milk in it and putting it to babies mouth. if you get them to the eating food stage (which I hope u do), give them oats and warm milk, my brother does to his baby hamsters and they love it.

If they are 9 days, you can get away with feeding them gerbil food soaked in water - get the highest quality food you can and get some small animal vitamins - the type you put in their water. Add the vitamins to the water, mix it then soak some of the food in it. When the food is very mushy then put it in the cage, and they should eat them. Its possible the mother was too old or too young to cope with the litter - this could be why she died.

Kitten replacement formula has too much protein. Use puppy formula. They should be old enough to lap the milk from your finger or from a needle-less syringe. Don't ever force milk into their mouths with a syringe though. Doing this will fill their lungs and essentially drown them. They should start nibbling available solids at 13-15 days.

Ring your local vet for some advice. They may be able to suggest a replacement milk you can feed with a syringe.

This looked like some good advice: Feed Kitchen formula from a syringe every 2 hours. Calling a vet for advice is a good idea too.