A balanced diet means less protein waste and litter box smell. How much protein do rabbits need to stay healthy? How much is too much?
Wasted protein makes your rabbit stink.
These are a simple questions with complex answers... because it 'depends' upon many other factors. However it is VERY EASY to tell if the protein in the food you are feeding your rabbit is getting wasted. This is because wasted protein will cause your rabbit's litter box to stink... and the smell gets worse as more protein is wasted.
THE SMELL OF WASTED PROTEIN:
The smell of ammonia comes from wasted protein. It is impossible for the waste of living things to be "ammonia free." However excessive ammonia is an obvious sign that protein in the food is not getting used EVEN IF IT IS GETTING DIGESTED AND ABSORBED! This is because the liver and kidneys have to work hard to rid the body of unused protein.
Even more strange is the fact that a rabbit can be deficient in meeting its dietary needs for protein AND simultaneously be overburdened with having to process and eliminate excess protein that it can't use (explained below).
Undigested protein also causes problems because it produces ammonia in the caecum which changes the pH and promotes the growth of bad bacteria. This causes gas, bad caecotroph formation, and increases the chance that your rabbit will suffer from diarrhea. Some brands add Yucca root to the food because it binds up ammonia so that you can't smell it. This is just a band-aid that covers up the problem. A properly balanced diet doesn't need yucca root.
The real issue at hand is based upon protein quality. The SOLUTION is to provide high quality protein in a proper balance.
This is a string of amino acids
Protein is made of building blocks called amino acids. All proteins are made from a unique combination of the standard 20 amino acids. They are linked together and form a three dimensional structure that has a special purpose such as a digestive enzyme (there is up to an an estimated 1,000,000 unique proteins in mammals).
The protein a rabbit eats is digested and broken down into individual amino acids that are used to make new proteins that the rabbit needs. While making these new proteins that rabbit draws from a 'pool' of amino acids.
This is a string of amino acids folded into a complete protein.
Some of them can be changed by an enzyme from one type to another while others are called "essential amino acids" because they have to be obtained in the diet.
It is very important that rabbits eat a balanced diet complete with the right ratio of all the essential amino acids.
A great analogy is to compare it to building a puzzle because it requires the right balance of all the right pieces or you won't finish. Sadly if a rabbit is deficient in a single amino acid (missing a few puzzle pieces) then they will go without the needed enzyme (like a mechanic without the right tools) and their health will be compromised. To some extent rabbits can compensate simply by eating more food but this leads to two problems. First, the rabbit will have to dispose of all the unused protein which stresses the liver and kidneys. Second, eating too many calories will cause the rabbit to get fat.
Balancing the "amino acid profile" should be according to the digestibility or bio-availability
for each individual essential amino acid
. Sherwood Forest Rabbit food is balanced according to the "true ileal digestibility" (the best way) of all the 11 essential amino acids (and it also includes chelated selenium for those of you who know about selenocysteine, the 21st proteogenic amino acid used in the all important thioredoxin reductase enzyme and others).
For this reason (and many others) Sherwood Forest rabbit food is SOY-FREE! Soy contains higher levels of "trypsin inhibitors" that inactivate protein digestive enzymes. This reduces the digestibility of the protein so it is not fully absorbed before it gets to the caecum. Remember this promotes the growth of bad bacteria that produce ammonia as a by-product.
MAINTAINING A HEALTHY WEIGHT:
There is one more thing I want to point out. The total amount of usable protein needs to be balanced with respect to the total amount of energy the diet provides. If there is too little energy then it forces the rabbit to 'burn' some of the protein to compensate and this causes more ammonia production and stresses the liver and the kidneys. If there is too much energy relative to protein it will cause the rabbit to store the excess as fat (especially true for brands that put in too many carbohydrates - i.e. grain!).