WHAT IS TO FEAR FROM SOYA IN PETFOOD ?

In petfood, soya grains are used for:

• their high protein content (35 to 37 %),
• the extraction of soya oil, that is rich in unsaturated fatty acids.

Digestibility of soya proteins

Proteins from soya have an interesting composition in undispensable amino-acids (richness in arginine, lysine…). Unhappily, they are penalized by a lower digestibility compared to proteins from animal origin: 80-85 % only, whereas the digestibility of beef greaves reaches 93-95 %, and those of poultry meats & by-products, 88-90 %. This lower digestibility can be explained by an unfavourable environment of the proteins: actually, soya contains 15 up to 18 % of dietary fiber.

Soya and digestive troubles

One often fears the effects of some antinutritional factors in soya. Effectively, raw soya contains substances that reduce the action of the enzymes which are necessary for a proper digestion of the proteins (ex: antitryptic factors). But these antinutritional factors are largely destroyed by the extrusion-cooking. Then, their influence is neglectable.

Soya is also accused to be the cause of dietary allergies. However, these kind of allergies are very rare in dogs and cats (less than 4 % of total allergies) ; when they exist, they are most often aimed towards other proteins: proteins from milk, beef, fish, or wheat gluten… In most cases, there is a confusion between allergy and food intolerance. The animal has just some difficulties to digest the food because of an insufficient digestibility, too poor energetic concentration, because of the low quality of some ingredients, etc…

In soya, what are really undesirable are not proteins. They are complex carbohydrates (stachyose, raffinose…), that are very bad digested by dogs and cats. These carbohydrates can ferment in the large intestine, and they are likely to produce very unpleasant flatulences. This is the reason why, when soya is incorporated in dog or catfood, its level of incorporation stays low.

Soya use in dog and catfood

In standard or economical products, soya brings extra-proteins that complete the animal ones in an interessant way. On the contrary, as soon as a maximal digestibility is required, grains and soya meals are rejected, because of the reasons explained above. This concerns all Royal Canin Premium or SuperPremium ranges.

In all these premium products, we do not include grains or soya meals, but we add soya oil, which is very interesting on a nutritional point of view. Compared to other vegetable oils, soya oil presents an ideal balance between essential fatty acids of both families: omega 6 and omega 3 (ratio: 6 / 1).

Conclusion

In petfood, soya use is limited by the relative low digestibility of proteins, and also by its poorer palatability compared to proteins from animal origin. However, specific technologic process would allow us to obtain purified soya proteins, way more digestible: concentrates or isolates of soya. For the moment, the cost of thes products is such that they are reserved to human food industry.

Donated by the Borg Cardona and Co. Ltd. visit Borg Cardona website