1. Do you have any extruded feeds?
Our pet foods contain extruded products. An extruder works like a giant meat grinder. As the grains (including corn, oats, soybean meal, etc.) travel down the barrel of the grinder, friction and heat are created and cooks the feedstuffs. As the pressure forces the cooked feedstuffs out little holes, the sudden release of pressure expands the feed into puffs. A knife cuts the puff at different lengths. That is how extruded dog and cat foods are made. Running the extruders, the coolers and other related equipment has a much larger cost associated in production than pelleting a feedstuff. Extrusion is only used where it is especially beneficial.
2. How many nutrients are absorbed into the dog’s system from the time the food enters the mouth to the time it passes out the other end?
Unfortunately, there is not a simple answer to your question. Various ingredients in pet food (all food for that matter) are absorbed differently. One way to think about it is to imagine two different wash cloths. One is made with terry cloth and one is made with denim. If both wash cloths have water dumped on them, the terry cloth will absorb the water a lot better than the denim.
A similar thing happens with nutrients. For example, a dog needs the mineral, copper, for bone growth and there are several sources of copper including copper sulfate and copper oxide. Just like the different type of wash cloths, the copper from copper oxide is not absorbed very well into the body whereas the copper from copper sulfate is absorbed very well.
The best general answer I can give you is that a good quality dog food has a TDN (total digestible nutrient) value of about 85%. That means that 85% of the dog food eaten (all nutrients) is absorbed into the body. Higher quality premium dog food like Iams, Hills, etc. would be higher. In some of the very cheap, off-brand name dog foods, this number can go to 70% or lower.