Feeding by tubing

Was wondering if anyone has experience feeding hens with tubing as I have been doing so for a few days as my chicken has a wrotten tongue. I only have one big syringe and tubing pipe and was wondering each time I use this do I need to sterilise by using a specific wash. Im only using the tubing on one chicken and I soak and repeatedly rinse the tubing and syringe in freshly boiled water. Is this hygenic enough for the chicken??