It may also be a good idea to take along a couple of days worth of your pets usual brand of food as it may not be readily available at your final destination. (norwalkanimalhospital.com)
Bring your kitten's usual brand of litter with you. (catster.com)
Try mixing in a small amount of the new food, along with the old brand, and gradually increase the amount of new food (recommended to me years ago by Purina Foods, when my girls usual brand had been discontinued) so their digestive system doesn't suffer too much shock. (catster.com)