WHAT CAN WE THINK FROM THE FIBER LEVEL IN DRYFOOD?

- What is the composition of vegetable walls?

Most of the fiber components are polysaccharides that escape the enzymatic digestion in the small intestine of non-ruminants animals : cellulose, hemicellulose, pectines, gums. Only one fiber component, the lignin, has a different chemicall composition.

Cellulose and lignin have a poor water solubility and water-holding capacity (WHC). Other polysaccharides are more soluble, and they have a high WHC : they are capable of forming highly viscous solutions or gel mixed with water.

Insoluble fiber tend to regularize the intestinal transit, whereas soluble fiber (ex: beet pulp) tends to slow it, but there are undispensable to the ecology of the large intestine.

- What is the interest of the crude cellulose percentage announced on the packagings?

Crude fiber (CF) level is measured with the official method of Weende (1920). It is one of the compulsory mentions in labelling. However, crude fiber estimates only a fraction of total cellulose and hemicellulose of a food or of an ingredient : crude fiber does not measure more than 25 to 30 % of total fiber.

CF analysis is a very bad tool for the prediction of vegetable walls content. It has no nutritional meaning. It can only be used for a raw comparison between ingredients. But it is completely useless for a qualitative appreciation of differences between petfoods which have a very low-fiber content.

Two foods may have the same level of crude fiber (announced on their packagings), but a different level of total dietary fiber : therefore, their digestibility will be different.

- How can we measure the total dietary fiber?

A fairly accurate determination is given by the Prosky's method (1984): it is a long and costly enzymatic dosage, but it allows a good estimation of the quality of ingredients. It is the only one meaningful nutritional notion.

What are the different types of fibers used by Royal Canin and its competitors?

The quality of fibers, as well as the quantity, is very important : to obtain really good digestive tolearnace, it is necessary to associate soluble and insoluble fibers.

- What are the dietary fiber values for our main vegetable ingredients ?

p. cent CF Dietary fiber
Wheat 2,5 9,0 to 12,5
Corn 2,5 9,0 to 11
Corn meal 0,5-1 2,6 to 4,5
Wheat meal 1 5 to 7
Hominy corn flake 0,5 1,9
Noodles 1 6,0
Fine bran 9 38
Beet pulp 17 59

- What are the consequences on digestibility?

No fibers = diarrhea
Excess of fibers = soft and voluminous stools Digestibility of dry matter (dDM), and consequently the quantity of feces produced (QF), are proportionnally related to the dietary fiber content : the more fiber there is, the less digestible it is.

• Between 4 and 6 % of dietary fiber : expected dDM : 82 to 88 % ; QF : 40 to 60 g per 100 g de DM ingested.
• Between 6 and 11 % of dietary fiber : expected dDM : 78 à 86 % ; QF : 50 to 80 g per 100g of DM ingested.
• Over 11% of dietary fiber : expected dDM inferior to 78 % ; QF superior to 80g per 100g of DM ingested.

The dietary fiber content is a quite reliable parameter for the digestibility prediction.`

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