How to grade your dog's food:
Start with a grade of 100:
1) For every listing of "by-product", subtract 10 points
2) For every non-specific animal source ("meat" or "poultry", meat, meal or fat) reference, subtract 10 points
3) If the food contains BHA, BHT, or ethoxyquin, subtract 10 points
4) For every grain "mill run" or non-specific grain source,subtract 5 points
5) If the same grain ingredient is used 2 or more times in the first five ingredients (i.e. "ground brown rice", "brewerâ?Ts rice", "rice flour" are all the same grain), subtract 5 points
6) If the protein sources are not meat meal and there are less than 2 meats in the top 3 ingredients, subtract 3 points
7) If it contains any artificial colorants, subtract 3 points
8 ) If it contains ground corn or whole grain corn, subtract 3points
9) If corn is listed in the top 5 ingredients, subtract 2 morepoints
10) If the food contains any animal fat other than fish oil,subtract 2 points
11) If lamb is the only animal protein source (unless your dog is allergic to other protein sources), subtract 2 points
12) If it contains soy or soybeans, subtract 2 points
13) If it contains wheat (unless you know that your dog isnâ?Tt allergic to wheat), subtract 2 points
14) If it contains beef (unless you know that your dog isnâ?Tt allergic to beef), subtract 1 point
15) If it contains salt, subtract 1 point
Extra Credit:
1) If any of the meat sources are organic, add 5 points
2) If the food is endorsed by any major breed group or
nutritionist, add 5 points
3) If the food is baked not extruded, add 5 points
4) If the food contains probiotics, add 3 points
5) If the food contains fruit, add 3 points
6) If the food contains vegetables (NOT corn or other grains), add 3 points
7) If the animal sources are hormone-free and antibiotic-free, add 2 points
8 ) If the food contains barley, add 2 points
9) If the food contains flax seed oil (not just the seeds), add 2 points
10) If the food contains oats or oatmeal, add 1 point
11) If the food contains sunflower oil, add 1 point
12) For every different specific animal protein source (other than
the first one; count "chicken" and "chicken meal" as only one protein source, but "chicken" and "" as 2 different sources), add 1 point
13) If it contains glucosamine and chondroitin, add 1 point
14) If the vegetables have been tested for pesticides and are pesticide-free, add 1 point
94-100+ = A
86-93 = B
78-85 = C
70-77 = D
69 = F
Here are some foods that have already been scored.
Authority Harvest Baked / Score 116 A+
Bil-Jac Select / Score 68 F
Canidae / Score 112 A+
Chicken Soup Senior / Score 115 A+
Diamond Maintenance / Score 64 F
Diamond Lamb Meal & Rice / Score 92 B
Diamond Large Breed 60+ Formula / Score 99 A
**** Van Patten's Natural Balance Ultra Premium / Score 122 A+
**** Van Patten's Duck and Potato / Score 106 A+
Foundations / Score 106 A+
Hund-n-Flocken Adult Dog (lamb) by
Solid Gold / Score 93 D
Iams Lamb Meal & Rice Formula Premium / Score 73 D
Innova Dog / Score 114 A+
Innova Evo / Score 114 A+
Kirkland Signature Chicken, Rice, and Vegetables / Score 110 A+
Nutrisource Lamb and Rice / Score 87 B
Nutro Natural Choice Large Breed Puppy / Score 87 B
Pet Gold Adult with Lamb & Rice / Score 23 F
ProPlan Natural Turkey & Barley / Score 103 A+
Purina Benful / Score 17 F
Purina Dog / Score 62 F
Purina Come-n-Get It / Score 16 F
Royal Canin Bulldog / Score 100 A+
Royal Canin Natural Blend Adult / Score 106 A+
Sensible Choice Chicken and Rice / Score 97 A
Science Diet Advanced Protein Senior 7+ / Score 63 F
Science Diet for Large Breed Puppies / Score 69 F
Wellness Super5 Mix Chicken / Score 110 A+
Wolfking Adult Dog (bison) by
Solid Gold / Score 97 A
FYI: Your second link doesn't work.
Personally, I would go with what your dogs do best on. Some people's dogs have loose stool on anything BUT Purina, others thrive on Canidae or Wellness. But that's a general score card to get you started.
Lab Question 
I was told you can mix and match but it must be given 6 hours apart. I used to work at a 
Maybe it has changed?
