I've heard of a lot of people having issues with BB. Orijen is a good kibble, but it's very rich and calorie dense. Definitely do a slow switch over a couple of weeks. Also keep in mind that overfeeding can cause loose stools/diarrhea. Since it's pretty calorie dense and has fewer fillers, you feed a lot less than you would a lower quality food. Start with a lower amount, and you can always work your way up if your dog starts looking too thin. I always found the recommended amounts on the bag to be more than any of my dogs or cats ever needed.
Asaah ~ KRW ABW Asaah LaLa, CGC