Congrats on the new addition!
When I changed Hercules' food, I gave him 75% of the old and 25% of the new, then 50% of both, then 25% of the old and 75% of the new. When that's ok, then I just gave him all of the new food. He didn't have any bad reactions, so hopefully that will work for you!!
Good luck!
Brandi & Hercules |