When "grain-free" foods first made their presence in the petfood market, the initial products were definitely state-of-the-art when it came to formulations. The concept of "grain-free" was very appealing to pet owners wanting to feed their dogs and cats better. Today's market is flooded with consumer choices for "grain-free" products and they no longer are state-of-the-art. I don't very often get frustrated with petfood companies because revenue is the bottomline regardless of the size of company. However, when it comes to "grain-free" products, some of the companies have made my blood pressure rise.
The real key with "grain-free" is actually regarding carbohydrates. In order to process and manufacture an extruded kibble product, a certain amount of starch is required to hold the kibble together through the high heat and pressure of extrusion. The success in the "grain-free" formulas is due to the use of potatoes and tapioca to maintain the kibble. In other words, while these products are "grain-free" they are far from carbohydrate or starch free. In some cases there is just as much carbohydrate and starch in some of the "grain-free" products as less expensive kibbles that contain grains.
The vast majority of dogs do not have issues with high quality grains and cooked carbohydrates as found in high quality kibble products. I don't feel grain-free is necessary in most cases (note that I did say MOST!). There are many high quality grain-including kibbles out there that would far surpass a couple of the "grain-free" products I'm about to discuss.
This weekend I pulled up 4 "grain-free" products online. There was only about $5.00 difference in cost between all 4 of them and only 2 are worth it. In addition I included the protein and fat concentration of "whole prey" for comparison. The whole prey concentrations came from our nutrition laboratory analysis and is an average for pork, rabbit, rats, chickens and mice.
DIET A: chicken meal, tapioca, chicken fat, pumpkinseeds, menhaden fish meal, alfalfa meal
Protein concentration = 42%
Fat concentration = 22%
DIET B: chicken, chicken meal, salmon, turkey meal, herring meal, potatoes
Protein concentration = 38%
Fat concentration = 17%
DIET C: Turkey meal, dried potatoes, potato starch, chicken fat, beet pulp, sunflower oil
Protein concentration = 21%
Fat concentration = 12%
DIET D: turkey meal, sweet potatoes, peas, potatoes, canola oil, potato protein
Protein concentration = $24%
Fat concentration = 14%
Protein concentration = 50%
Fat concentration = 30%
Diet A and B both are closer in nutrient composition to whole prey; however, I'd like diet B a lot better if it had a little more fat. Fat becomes very important for performance dogs and if the fat concentration was over 20%, diet B would easily be my pick. That said, it is still my favorite due to the high quality proteins in the list. Diet C and D are the ones that caused my blood pressure to rise. Petfood companies are very smart and in these 2 cases they are absolutely taking advantage of consumers. These 2 products did not cost that much different than A and B but you will notice they contain approximately 44 and 33% less protein and fat, respectively. The rest will be predominately carbohydrates and considering they are "grain-free" that would mean starch. In addition, the companies that are manufacturing diets C and D do something called "ingredient splitting". They can't simply list "potatoes" on their ingredient lists as diet B did because if they did, potatoes rather than turkey meal would be the first ingredient. Both of these diets are made up of predominately potatoes. I call them the "potato salad" diets. Most of us that eat potatoes know they aren't the most expensive produce items in the supermarket so know that if you are purchasing these products from petfood companies, you are paying a premium price for potatoes.
When selecting a "grain-free" product, look for several protein sources in the top 5 ingredients (not including pea protein or potato protein...I'm OK with these ingredients but I don't want them in the top 5). Look for animal protein sources. Also, look for just a single listing of potatoes or tapioca in the top 7 ingredients. Don't stop at the ingredient list. Look at the guaranteed analysis and you want to see more than 35% protein and a minimum of 17% fat.