Gastrointestinal is an adjective meaning of or pertaining to the stomach and intestines. A tract is a collection of related anatomic structures or a series of connected body organs.
You can obtain mother's milk replacer for young kittens at many of the pet stores in the area. When the kittens are 8 weeks or older, they no longer need the milk but may enjoy it anyway. Milk that has been specially processed for cats to consume safely is available from many local groceries. Water. Keep clean, fresh water available to your kitten at all times.
Prepare to feed the kittens. Sterilize the bottle and nipple in boiling water, then let them cool completely on a clean towel. Mix up the milk replacement formula using a little whisk to get the lumps out. You should warm the milk up to 95 - 100 degrees before feeding it to the kittens. As a final check, drip a few drops onto the underside of your wrist to make sure it's not too hot. Always make sure the kittens themselves are warm before feeding them. Never feed a kitten whose temperature is less than 95 degrees.