Novel proteins

After reading through a lot of threads I noticed that people try to avoid "novel proteins." What are they and why should they be avoided?

Many pet foods use common proteins: chicken, duck, beef, turkey. Novel proteins are proteins that are not typically found in pet food: rabbit, pork, pheasant, veison, even kangaroo among others

I'm not sure where you read that novel proteins should be avoided. Typically a cat who has a allergy or senitivity to a common protein like chicken will be put on a "limited ingredient diet" that has a novel protein. The thought is that because the novel protein is less commonly found in pet food, there ie less of a chance that the cat would also have  similar allergy or senitivity to a novel protein.

Some people like to rotate novel proteins with common proteins anyways. It keeps the cat from getting bored with the food and some people feel that it lesses the chance of an allergy or sensitivity from developing in the first place.

Here's a thread where members discuss brands of novel protein food: http://www.thecatsite.com/t/306947/your-favorite-brands-of-novel-protein-canned-cat-food

Thanks! Maybe I misread the other thread where I saw it. I'll check out that thread now!