Grant: Collaborative Research and Development Grants

Protein is made from amino acids, some of which can be synthesized by the body (non-essential amino acids), while others must be consumed in the diet (essential amino acids). In order for cells to make necessary proteins, all of the amino acids must be available and in the right proportion. Certain amino acids are also used to make other metabolites, such as creatine, an energy source in muscles. Two important amino acids used to make creatine are arginine and methionine. Arginine is combined with glycine to make guanidinoacetate (GAA), which in turn is methylated by methionine to make creatine. Our research model, the young piglet, consumes about 25% of its whole body creatine requirement as pre-formed creatine in sow's milk; thus, the remaining 75% is synthesized from arginine and methionine. Because of rapid growth in early life, these amino acids are in high demand and can easily become deficient. We have recently discovered that creatine synthesis is limited in piglets given creatine-free diets, particularly when arginine intake is low. We also found that creatine synthesis was proportional to the amount of arginine in the diet. Thus, we question whether growth is affected if dietary arginine and/or methionine are diverted to creatine synthesis when dietary creatine is not provided. Moreover, GAA has been approved as a feed supplement in poultry and this work will determine if it is also effective in pigs at sparing arginine, an amino acid known to be limiting in piglets. This work will help define the needs of these critical nutrients in growing pigs. Because protein and amino acids are the most expensive component of swine diets, minimizing their supplementation by feeding creatine and GAA would reduce overall costs for pork producers in Canada.