Mathai, J. K, J. K. Htoo, J. E. Thomson, K. J. Touchette, and H. H. Stein. 2016. Effects of dietary fiber on the ideal standardized ileal digestible threonine:lysine ratio for twenty-five to fifty kilogram growing gilts. J. Anim. Sci. 94:4217-4230. Link to full text (.pdf)

Use of high-fiber, low-cost ingredients, such as co-products from grain processing industries, in swine diets is increasing. Pigs fed diets containing high levels of fiber have increased intestinal mass due to increased amount of microbial fermentation in the hindgut. Therefore, they also have increased endogenous loss of amino acids in the form of mucins, the proteins that line the intestinal tract. The abrasiveness of fiber stimulates the secretion of mucins as well. These factors may cause the threonine requirement to be increased in high fiber diets, because threonine is present in large amounts in mucins. Therefore, an experiment was conducted to determine the effects of dietary fiber on the optimum threonine:lysine ratio (Thr:Lys) in 25 to 50 kg growing gilts.