The 2 amino acids that are used to supplement animal proteins are L-Lysine and DL-Methionine. L-Lysine is made by a fermentation process. The DL-Methionine however is synthetic and is in most animal feeds like dog, cat, chicken, and pig. The people I know that seriously compete with their sport dogs internationally include a raw diet to keep dogs healthy and competitive. Im sure there are plenty of arguments for and against synthetic additives, but I like to add some real amino acids to my flocks diet (and my dogs). Purina Flock raiser with 20% plant protein and Methionine is $20.99 at my local TSC. Hudson Multi Flock 23% with plant, animal protein, and Methionine is $20.95 delivered to my door.