Crude Fiber
Why is fiber important in a rabbit diet and how much do they really need?
A rabbit food label that reports its crude fiber content is too vague to make any judgments on how it will affect your rabbit’s digestive health, because not all fiber is created equal! Most people think of fiber being used to speed the passage of food through the digestive system with the lack of it causing digestive problems such as constipation or diarrhea. Rabbits are different. Fiber for rabbits should be divided into different categories because, in the rabbit, only certain types of fiber actually act like fiber.
Also, because rabbits ferment their food (described below) rabbits should always have food available for them to eat.
Minimum levels of this fiber (lignin - woody material in the stem) are needed to prevent digestive troubles but rabbit food labels don't even report a guaranteed amount of lignin (they only report "crude fiber"). Furthermore, even if they did numerically meet this criterion it is simply not enough.
This is because care needs to be taken to ensure that the lignin fibers are of the right particle size or they won’t be able to serve their function and can possibly end up contributing to digestive troubles.
Just how long should long-stem fiber be? Doesn't the rabbit chew it up anyways? The truth is that lignin is woody and tough and resists being broken down. The chewing process breaks it up into relatively small fragments but they naturally remain large enough to function properly for the rabbits digestive system.
The way it should work: The caecum is the key to rabbit digestive health!
Rabbit food too high in easy carbohydrates (grain and grain by-products) or indigestible protein that doesn’t get absorbed BEFORE it reaches the caecum at the end of the small intestine (just past the ileum) becomes CANDY FOR BAD BACTERIA.
These bad bacteria can grow unrestrained and cause digestive troubles that lead to bloating and diarrhea. They also stress the rabbit immune system.
The Nursing Doe and Her Kits: Young rabbits that are starting to consume solid food are more prone to imbalances until their digestive system develops more fully.
Timothy Hay for rabbits
Also, because rabbits ferment their food (described below) rabbits should always have food available for them to eat.
Indigestible Fiber: Long stem hay?
This type of fiber (lignin) functions in the rabbit digestive system the way we normally think of fiber.
Click on the picture to see up-close what rabbit food should look like.
This is because care needs to be taken to ensure that the lignin fibers are of the right particle size or they won’t be able to serve their function and can possibly end up contributing to digestive troubles.
Just how long should long-stem fiber be? Doesn't the rabbit chew it up anyways? The truth is that lignin is woody and tough and resists being broken down. The chewing process breaks it up into relatively small fragments but they naturally remain large enough to function properly for the rabbits digestive system.
- Lignin fiber particles need to be larger in size (approximately 1.7 mm or larger) than the other particles in the feed. Our recipes are designed to make sure that our rabbit food provides enough lignin for your rabbit and our milling process ensures that they aren't too small! Look at the above picture and compare it to other rabbit feeds. Rabbit food that is finely ground prior to pelleting will increase the likelihood of digestive troubles.
- If there is not enough of these particles (or if they are too small) then digestion will be slowed and this increases the likelihood of diarrhea.
Digestible or Fermentable Fiber:
Ironically some other types of fibers aren’t used like fiber at all.- These fibers are used as an energy source like we use carbohydrates. However, the energy is absorbed by the rabbit in the form of volatile fatty acids (fat) and not carbohydrates!
- Once again these types of fibers can only serve their function if they are incorporated into rabbit food in the right particle size.
- If the rabbit food is made correctly then these types of fibers will eventually end up in the caecum (an enlarged appendix or dead-end chamber off of the large intestine... see picture below) where they will serve their purpose.
- These particles need to be smaller in size than the indigestible fibers.
- Take a close look at the rabbit food pellet. If it is comprised of all small particles (less than approximately 1.5 mm) then you know that all the ingredients will likely end up in the caecum, some of which may cause problems.
The Caecum and how Fiber Affects Rabbit Health
Rabbit digestive system
- Rabbits are unique because feed ingredients that are normally indigestible to other animals can be fermented (digested) by microorganisms within the caecum in much the same way a cow uses one of its “four stomachs” to ferment or digest its food.
- These microorganisms have the ability to digest certain fibers releasing energy and making nutrients available for the rabbit. In return the rabbit constantly feeds the microorganisms these special fibers and houses them in a warm protected environment.
- For optimal ceacal health it is very important that rabbits always have food available to eat and water to drink!
Don't feed rabbits too much grain!
The Nursing Doe and Her Kits: Young rabbits that are starting to consume solid food are more prone to imbalances until their digestive system develops more fully.
- At this young age the baby rabbits inoculate their caecum with microorganisms from their mother. This makes it very important for the doe to be consuming a balanced feed that promotes the growth of good bacteria rather than bad bacteria.
- Because of this baby rabbits benefit from rabbit food that is higher in natural oil and lower in carbohydrates. Interestingly this same style of feed supports the Doe while she is lactating (providing milk for the baby rabbits).
