My girls are 20 lbs, and the vet told me I could add a tablespoon a day but a teaspoon is all that was needed for the transition. (I found out too much kefir will firm the poo too much.) Since Atlas is bigger and eats more food, I would start with a tablespoon once a day and see how it goes for a couple of days. If after a couple of days his poo is still soft or starts out firm and gets softer during the day, I would give a tablespoon twice a day. My girls love the kefir, and I just put it in their bowl and they lick it up immediately and then stand there licking an empty bowl for another minute. It is fine to mix the kefir with the food, especially during the transition, but long term for getting bacteria better established in the gut it works better 30 to 40 minutes before the meal.
