Grains in dog food - healthy or not?

However the coming together may have happened, it eventually led to the domestication of the wolf and the dog came into being - man's best friend. In the long time that dogs have lived with us, they have changed and moved further and further away from the original animal, the wolf. On the highly interesting evolutionary changes from the wolf to the dog we have gone into detail in a separate article. These range from changes in shape and color to the development of facial muscles to facilitate communication with us humans.

What is the difference between the digestion of wolves and dogs?

Wolves are not pure carnivores, more precisely they belong to the carni-omnivores. They are designed to eat their prey as a whole - and this includes not only the muscle meat, but also, for example, the stomach contents of the prey. Since these are in the vast majority of cases herbivores, wolves can also digest plant food to a certain extent and, in moderation, even starch.

Just like the wolf, the dog is not a pure carnivore, although it can digest plant food significantly better than the wolf. Especially in the breakdown of starch from cereals, the dog has an advantage: Due to an increased amylase activity, it has a significantly higher tolerance in the digestion of carbohydrates.

From starch and amylase

Cereals such as wheat, rye, rice and also potatoes are enormously rich in starch. Starch is a carbohydrate and a polysaccharide macromolecule. It is full of usable energy, provided you have the enzyme amylase and can therefore break it down. Alpha-amylase, which is found in the digestive tract, can break down starch polysaccharides into maltose, maltodextrose and various oligosaccharides, making them usable by the organism. We humans possess five isoforms of alpha-amylase, which are found in saliva and pancreatic secretions. The enzymatic activity in saliva therefore enables us to break down starch while chewing. Bread therefore tastes sweet if you chew it for a long time, because at some point you can taste the sugars that have been broken down. Dogs also have amylase, and significantly more than the wolf. It is not found in saliva, but in not so small quantities in pancreatic secretions - the dog's digestive tract is therefore able to break down and utilize certain amounts of starch from cereals or similar.

Selection for the ability to digest starch

The ability to digest starch is related to the number of copies of the salivary amylase-encoding gene AMY1. The more copies a person has, the better starch can be broken down and utilized. Even we humans have not always been able to digest starch to the same extent as we do today - the ability to do so only built up with the switch to a starch-rich diet.

In the Neolithic period, mankind's way of life changed from a hunter-gatherer society to a sedentary one practicing agriculture and animal husbandry. This change did not occur everywhere in the world at the same time, but began in the Fertile Crescent in the Middle East around 10,000 BC and spread from there to the wider world over thousands of years. The more cereals, tubers and products from them were consumed, the better the human digestive system adapted to the cereal-rich food source. Those who happened to have more gene copies for starch digestion had a higher chance of being well nourished and producing more offspring. This can still be observed today, because not everywhere in the world do people possess the same number of copies of the AMY1 gene. For example, significantly fewer are found in the original peoples of Russian Yakutia, who feed mainly on meat and fish, than in Central Europeans with cereals as their staple food.

We humans are not the only ones with many gene copies for starch splitting; our domestic dogs also possess them. In them, the AMY2B gene is responsible for it. In a study[1] that compared genetic material from wolves, early domesticated dogs and present-day dogs, it was shown that wolves on average possess significantly fewer gene copies than present-day and also early domestic dogs. This suggests that dogs, along with us humans, evolved the ability to break down starch and use it as food. Again, there was probably a clear selection advantage for those individuals that could eat not only the meat, but also the cereal and tuberous waste of settlements. Just as with us humans, not all dog breeds known today have the same number of copies of the AMY2B gene. For example, dog breeds from arctic regions, such as the Siberian husky, have very few copies. Since this region is free of agriculture, this supports the hypothesis that the ability of starch digestion in dogs evolved in connection with the beginning of agriculture by humans.

Within the dog population, the endowment of copies of AMY2B varies. Therefore, no clear "cutoff" value for starch digestion can be established and further research is needed on the relevance of exact copy number.

Does grain belong in dog food?

Dogs are genetically designed to digest starch - presumably because they have lived with farming humans for thousands of years. So, dogs can digest grains and use the starch they contain as a useful source of energy. A frequently raised argument against grains in food is the risk of allergies. Dogs can develop massive allergies to grains, mostly to the proteins they contain. However, grain protein is no more allergenic than other proteins. In other words, the likelihood of an allergy is similar to that to various animal proteins.

What speaks against grain in dog food?

Dogs with allergies to grain ingredients, such as wheat protein, should not be fed foods containing grain - just as dogs with allergies to beef protein should not be fed beef. In the former case, grain should be avoided at all costs. Another argument against grain is its high energy content. This can be a problem, especially for obese dogs or dogs with a tendency to overweight, as the energy requirement can easily be exceeded with cereal-containing food if the dog does too little exercise.

What speaks for grain in the feed?

Dogs are able to break down and use starch - whether this comes from tubers such as potatoes and sweet potatoes or from grain is not decisive for the digestion process itself. Cereals are thus a useful source of energy - of course, only for dogs that can tolerate them. Since it is inexpensive, can be manufactured thus over a grain portion also energetically valuable dog food for the small purse. By the way, it reduces the amount of meat in the food and thus the ecological footprint of the four-legged friend.

In conclusion, it can be said that there are countless opinions about the "right" dog food - everyone is right who provides their dog with all the nutrients they needs for a healthy dog life. This can be the case with or without grain. A proper ration and requirement calculation makes sense for every dog.