Amino acids come primarily from the breakdown of the proteins in the diet. These amino acids are necessary for maintenance and repair of tissue and organs, and the production of enzymes, hormones and antibodies. Basically, amino acids are needed for all bodily functions.
A dog must be fed enough variety of proteins to supply all the necessary amino acids. Very few protein sources, both plant and animal, have a perfect amino acid profile. Therefore, you should feed a product with a variety of ingredients, unless your dog has excessive food sensitivity.
There are 22 amino acids required by the animal body. The body can synthesize (make) twelve of these when it is fed a properly balanced diet. These are called Non-Essential Amino Acids. This leaves 10 Essential Amino Acids that must be supplied in the diet fed. The Essential Amino Acids are arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine.
Remember that all proteins are not created equally in regards to amino acid profile and digestibility. The amino acid profile of each source is quite scientific so I will not go into that much detail here. A protein could have a perfect profile but have low digestibility and will not meet the needs of your pet. The ability of a protein source to be used by the body to supply amino acids is called the “biological value” of the protein. Eggs are a nearly perfect protein source and therefore set the standard against which all other proteins are measured. Eggs are given a value of 100. Fish meal and milk have a value of 92, muscle and organ tissue is around 78 and soybean meal is valued at 67. Meat, bone meal and wheat are valued at about 50 and corn at 45. Basically this means that eggs are almost 100% digestible and amino available, while wheat and corn are only 50% digestible and available to meet amino acid needs.
Look at your dog food label. If it has lots of grains and low-end meat by-products, then the digestibility is low, which makes the amino acids in the ingredient less available. Protein percentage listed on the label is “crude” or total protein. This means nothing about digestible protein, so you must educate yourself about ingredients. See some of my other articles for more information on specific ingredients.
Yes, it is all scientific and beyond the scope of most of us. Just know that the better quality the ingredients, the higher the biological value and digestibility. Also remember that high price does not always mean highest quality. See my dog food reviews for examples.
Deficiencies in amino acids will show up as decreased appetite, poor growth in young dogs, weight loss, rough or dull hair coat, increased illness, poor reproductive performance and low milk production in breeding animals. Some deficiencies don’t show up immediately and are considered sub-clinical. A dog may appear perfectly healthy, but be overly susceptible to illness or infection.
When feeding a good quality commercial feed with a meat meal as the first ingredient and a mix of other quality proteins such as egg and other meats, you should not have any deficiencies. Some labels even include guarantees of certain amino acids. This is not a labeling requirement, but is nice.
I like the grain free products personally. They aren’t for everyone, if for no other reason but the expense. People ask all the time if I am worried about feeding all that protein because they have been told it causes kidney disease. Most of the grain free products are over 30% protein. I always say no because I currently have a 16 year old dog and the one before him lived to almost 18 years old. Protein will first be used to supply all the amino acids needed and then be metabolized into energy. All excess is excreted in the urine, but doesn’t cause kidney damage. Of course if your dog has kidney problems, a high protein diet is not recommended.