Tryptophan is an indispensable AA that is often limiting for growth in pigs fed corn-soybean meal-based diets. Tryptophan may act as a regulator of feed intake by enhancing serotonin signaling in the brain, because Trp is a precursor for serotonin. High Trp intake increases feed intake, and this is partly attributed to increased serotonin synthesis. Availability of dietary Trp in the brain is considered the rate-limiting step in hypothalamic serotonin synthesis. However, to be transported into the brain, Trp competes with other large neutral AA such as Val, Leu, Ile, Tyr, and Phe for a common transporter (L-type AA transporter 1) to cross the blood-brain barrier.

Blavi, L., D. A. Rodriguez, and H. H. Stein. 2018. Nutritional value for growing pigs of different sources of distillers dried grains with solubles (DDGS). Pig 333. Sep. 10, 2018. Link to full text.

Cerisuelo, A., P. Ferrer, E. Gómez, T. Woyengo, H. Stein, J. Cano, and O. Piquer. Digestible energy content of Camelina sativa co-products for growing pigs. 2018. 14th International Symposium on Digestive Physiology in Pigs. Adv. Anim. Biosci. Volume 9, Issue S2, 9:S184. (Abstr.). Link to abstract

Cerisuelo, A., P. Ferrer, E. Gómez, H. Stein, T. Woyengo, J. Cano, and O. Piquer. 2018. Protein and amino acid digestibility of Camelina sativa co-products for growing pigs. 14th International Symposium on Digestive Physiology of Pigs. Adv. Anim. Biosci. Volume 9, Issue S2, 9:S148-149. (Abstr.). Link to abstract

Distillers dried grains with solubles (DDGS) is a co-product of ethanol production that is often used in diets fed to pigs because of a relatively high concentration of amino acids (AA), energy, and digestible phosphorus. However, during the cooking and drying steps, the high temperature and concentration of moisture makes DDGS susceptible to the Maillard reactions, resulting in formation of sugar-amino acid complexes. Maillard reaction products result in reduced standardized ileal digestibility (SID) of amino acids (AA), with Lys being the most sensitive AA. However, there is limited information about how heating affects the concentration of digestible energy (DE) and metabolizable energy (ME). Therefore, the objective of these experiments were to test the hypothesis that both the degree of heating and the time that heat is applied will affect the concentration of DE and ME and the SID of AA in DDGS fed to growing pigs.

Double-low rapeseed meal (RSM) is currently used as a protein ingredient in animal diets. Heat treatment of RSM at varying processing conditions removes the residual hexane and efficiently reduces the glucosinolate content. However, variations in heat processing temperatures and duration of heat treatment may result in Maillard reactions, resulting in the formation of sugar-amino acid complexes. Maillard reaction products result in reduced standardized ileal digestibility (SID) of amino acids (AA), with Lys being the most sensitive AA. However, there is limited information about how heating affects the concentration of digestible energy (DE) and metabolizable energy (ME). Therefore, the objective of this experiment was to test the hypothesis that both the degree of heating and the time that heat is applied will affect the concentration of DE and ME and the SID of AA in double-low RSM fed to growing pigs.

McGhee Molly L. and Hans. H. Stein. 2018. Apparent and standardized ileal digestibility of AA and starch in hybrid rye, barley, wheat, and corn fed to growing pigs. J. Anim. Sci. 96:3319–3329.  Link to full text.