Empty Quiver mentioned the use of non-protein nitrogen sources in cattle feed (i.e. urea). This is not a “shenanigan” that is played by test labs. Cattle are ruminants, having a multi-chambered stomach in which microbial fermentation of feed stuffs takes place. Rumen bacterial population can use this non-protein nitrogen to build amino acids, which in turn are assembled into microbial proteins. These microbial proteins are then digested by the cattle as an excellent protein source.
Empty Quiver is correct in stating that the reported protein content of a feed can elevated by adding non-protein nitrogen sources. This is due to the fact that in order to determine the protein content of a feed, the nitrogen content is measured and the protein content is calculated based on the nitrogen content (protein is 16% nitrogen).
Dogs on the other hand are simple stomached animals, and would not benefit from added non-protein nitrogen sources. I am not going to tell you a particular brand of food that is best, but here are some guidelines to keep in mind.
-Dogs need protein, fat, carbohydrates, vitamins and minerals and the levels of these nutrients will change based on the dogs stage of life, breed, activity level, ambient temperature etc.
-Cheap dog foods use cheap ingredients, but some expensive dog foods also use cheap ingredients.
-Unless I have specific details about a specific dog food, I would recommend sticking with one of the reputable high quality dog foods. The reputable companies spend hundreds of thousands of dollars in research and development to try to keep a competitive edge over the competition, and this benefits your dog.
-Pretty colors and fancy shapes have no nutritional value whatsoever.
-I like to see meat products as the first ingredient. Dogs can utilize the amino acids in the proteins for their own protein needs, or convert them to energy as needed. Meat also contains the essential amino acids that the dog is not able to manufacture on their own.
-Fats are used for energy. Fats are also very important in several regulatory activities within the body including the formation of some hormones, and cell membrane integrity.
-Many dog foods use cheaper ingredients such as corn meal as a filler. Dogs can utilize the carbohydrates in the corn for energy, but the digestion is less efficient than for fats and proteins. Less efficient utilization means that for a given volume of food, there will be less food utilized, thus more to clean up in the kennel. Additionally, the pathways for carbohydrate utilization are different than those for energy utilization from proteins and fats. Carbohydrates are digested to simple sugars (glucose). As glucose levels in the blood increase, insulin levels increase to stabilize blood glucose levels. One of the things that insulin does is signal the adipose cells to start storing the extra glucose as fat. Over feeding of energy, especially carbohydrates can lead to obesity.
Some general guidelines
Protein Fat
Puppy 28% 17%
Adult 18% 9-15% depending upon temp, activity level, breed etc
Performance 25% 20%
I had better stop rambling, I hope this helps, and does not just muddy the water.
