I've been looking at Acana, it is lower in calorie than Orijen probably due to it having more plant material in (I think it's about 10% less meat).

I'm going to order the lamb one for Shiro as he puts on weight really easy, I think it may be because he is fixed whereas Chichi and Millie aren't. They both seem to be able to scoff whatever they want and always be a perfect weight (I wish I could the say the same about me).