I highly doubt that without a reliable source. Proteins don't "rot", they fall apart into amino acids which are absorbed. I have never heard amino acids becoming unusable due to long digestion tracts.
The reason I've always heard about carnivores having shorter digestive tracks is that animal matter is much easier to digest than fiber-and-cellulose-laden plant material. In most organisms (expect humans) digestion takes the most % of energy so shortening the digestive tract if it's not necessary is a no-brainer for evolution.
The reason I've always heard about carnivores having shorter digestive tracks is that animal matter is much easier to digest than fiber-and-cellulose-laden plant material. In most organisms (expect humans) digestion takes the most % of energy so shortening the digestive tract if it's not necessary is a no-brainer for evolution.