As presumably your growing pigs, then protein usability is key. Crude Protein deos not tell you how much food the pigs can convert to muscle.
The key here is that protein is broken down into amino acids in the pigs digestive system, and these form the building blocks for different proteins that the pig then uses to build muscle. However the amino acids need to be in the right ratio for the pig. So for instance if each protein in the food contains 1 A, 2 B and 3 C amino acids, and the pig builds muscle by combining 2 A, 1 B and 3 C to make one protein, then if you take 10 proteins you'll have
A 10
B 20
C 30
From this you can build only 5 protiens, as you need 2A's for each and you only have 10 A's to play with. For these 5 proteins you'll need 5B's using 5 B's, leaving 15 as waste. For C's, again you have 5 proteins, each needing 3C's, so use 15 C's, leaving 15 as waste.
So in effect from 10 original proteins you can only make 5.
If you do the above with Soya and Lysine as the animo acid, you can understand why pig food has lysine added to it.
For your brewers grain, lysine again is lacking, as a rough guide 5-20kg pigs need the "perfect" column, ie you would feed protein with the same levels of each of the AA (Amino Acids) as the pigs need. From the article you quote I have completed the next 3 columns. "Brewers" is what the article says it contains (bottom of article), "needed" is what can be used from that and "waste" is what cannot be used.
AA Perfect Brewers Needed Waste
Lysine 100 3.3 3.3 0.0
Isoleucine 60 5.4 3.2 2.2
Leucine 100 8.3 3.3 5.0
Methionine 30 1.2 1.0 0.2
Phenylalanine95 4.7 3.1 1.6
Threonine 65 3.2 2.1 1.1
Tryptophan 18 1.3 0.6 0.7
Valine 68 5.4 2.2 3.2
Histidine 32 1.8 1.1 0.7
So out of every 34 units, 20 will be used and 14 will be waste. You'll see that if you added more lysine, you could achieve a higher conversion rate, and have less waste.
Of course that only deals with protein, and you'll also need to consider vitamins and minerals as well a lipids and carbohydrates
As the pigsite suggests, you'll need to use this as only a portion of the feed, and the advice that higher than 35% would have a detrimental effect is interesting.
