Dry dog foods might all look pretty similar but what you might not realise is that the methods used to produce them can vary dramatically and that the way a food is processed can have huge consequences for the nutrients contained within. In this article, I'll be looking into the various methods manufacturers use to make dry dog foods and their potential consequences for your dog.
Over the last few decades, one factor has shaped the pet food industry more than any other: convenience. These days, many of us struggle to find the time to prepare a nutritious, balanced diet for ourselves, let alone our dogs, so it's no surprise that the demand for complete dog foods has increased by 90% in the last 10 years. And amongst complete foods, dry completes - the most convenient options of all, have come to completely dominate the pet food market from top to bottom. Their draw is obvious: they provide everything your dog needs in a single bag, they are easy to store and (usually) relatively inexpensive. But does all this convenience come at a price?
Virtually all dry foods are made by grinding and mixing the raw ingredients into a dough which is then cooked and separated into the individual biscuits. Nutritionally, the process has some advantages: The grinding and cooking, for example, certainly make carbohydrates easier to digest whilst also destroying any pathogens and parasites that might be present in the raw ingredients. Unfortunately though, the very same processes can also have some detrimental effects on the food:
Vitamins are delicate things. From the moment an ingredient is harvested, its natural vitamin levels start to drop. Over time, the vitamins continue to gradually degrade but certain factors can considerably speed things up. High temperature, for example, can destroy vitamins very quickly. Unfortunately, as you might imagine, the cooking and drying of dry dog foods often involves VERY high temperatures. As a countermeasure, virtually every complete food has it's vitamin levels topped up with a synthetic multi-vitamin but most synthetic vitamins are generally regarded as poor substitutes for the real thing.
High temperatures can also dramatically effect the structure of proteins, forcing the amino acid chains to bend and twist into new forms. This is called 'denaturation' and it's effects on the nutritional quality of a food is unclear. Studies conducted on vegetable proteins in dog food suggest that cooking at temperatures high enough to cause the proteins to denature might actually make them easier for dogs to digest. Whilst the effects of similar temperatures on the digestibility of meat proteins haven't been studied in the same way, some nutritionists claim that the structural changes could make them harder for dogs to digest and more likely to lead to intolerance which would explain why some dogs react to a particular meat when it is in a dry food but are fine when fed the same meat raw. The enzymes naturally present in raw foods are regarded by many as extremely important factors in a dog's diet but since they are made of protein, they are completely destroyed during denaturation.
At high temperatures, omega 3 and 6 oils, both of which are essential to keeping your dog healthy, can be lost. Unlike vitamins, most manufacturers don't replace lost essential oils after cooking.
Not all dry foods are bad - far from it in fact! If enough care has been taken during manufacturing, dry foods can be nutritionally excellent. Different types of foods are made in very different ways so the best place to start is with the type of food you're feeding...
Although most dry foods look pretty similar, the methods used to make them and the ramifications for their nutrients can be quite different...
Examples: Bakers Complete, Pedigree Complete, James Wellbeloved dry, Royal Canin dry, Burns, Orijen and many, many more.
The vast majority (around 95%) of dry dog foods are made by a process called extrusion. Extrusion is popular with manufacturers because it is inexpensive, quick and flexible, allowing for virtually any combinations of ingredients.
The extrusion process starts with the ingredients being mixed together and ground into a dough. The dough is then pushed through the inside of the 'extruder' (essentially a long metal tube) where it is continually mixed while being heated under pressure to temperatures of up to and sometimes even over 150°C. At the end of the extruder, the dough is pushed through a 'die' (a lot like the Play-Dough factory for the parents amongst you!) which gives the biscuits their shape. As it leaves the pressure of the extruder through the die, the cooked dough expands quickly while it is continually sliced by a rotating knife to form the individual pieces. Extrusion is a very fast process, often only taking about 5 minutes to get to this point. The final stage is to dry off the pieces and make them crispy by whisking them through a dryer for up to 20 minutes at temperatures sometime