Grant: Discovery Grants Program - Individual

In piglets, both arginine and methionine are essential amino acids and have several important metabolic roles other than protein synthesis. For example, both amino acids are necessary for creatine synthesis which is in high demand in young growing pigs. Arginine is converted to guanidinoacetic acid (GAA) in the kidney and then methylated by methionine to form creatine in the liver. We have previously demonstrated that when dietary arginine or methionine is limiting, creatine synthesis is particularly impaired. In fast growing animals, the demand for creatine cannot be met by new synthesis and it has been estimated that only three-quarters of creatine needs can be synthesized, with the rest of creatine coming from the diet. Creatine and GAA can potentially be very effective as growth-promoting feed supplements, especially in all-grain diets which are typically creatine-free. They can also be particularly effective as supplements in milk-based weanling diets due to their low arginine content; if creatine or GAA are supplemented to these diets, then arginine is free to be used for other functions. The use of creatine and GAA in the swine industry has enormous potential as supplements in young pigs, given they can `spare' arginine and methionine early in life and perhaps improve growth and health. *Our overall objective is to evaluate the interactions among methionine, arginine, creatine and GAA. Specifically, we would like to answer the following questions: How much dietary arginine and methionine are required to synthesize creatine? Can we spare methionine and arginine for growth by adding creatine to the diet? Which organs are involved in creatine metabolism and how is GAA and creatine in the blood used? How available to the body are creatine and GAA supplements and do we need to add more methionine to a GAA-supplemented diet? The potential use of creatine and GAA as novel supplements will assist the pork industry in achieving the highest quality pork at the lowest possible costs, through optimum diet formulation. Avoiding over-formulation of diets will also contribute to environmental sustainability by reducing nitrogen pollution.*