Recent Advances in Swine Amino Acid Nutrition

Recent advances in swine protein nutrition are characterized by the development of functional amino acids (AA) in regulating fetal and postnatal survival, growth and development. These AA include arginine, glutamine, glutamate, proline, leucine, cysteine and tryptophan. Due to limited knowledge on AA nutrition, pork producers have traditionally paid little attention to supplementing the arginine family of AA to swine diets. Results of recent studies indicate that functional AA serve important regulatory functions in nutrient metabolism, protein turnover, and immune function, therefore enhancing efficiency of feed utilization by pigs. The underlying mechanisms include activation of nitric oxide, mammalian target of rapamycin, gaseous signaling, and AMP-activated protein kinase pathways, as well as anti-oxidative function. Dietary supplementation with arginine, glutamine, proline or leucine to weanling piglets enhances their growth performance. Arginine or glutamine is also effective in increasing milk production by lactating sows. Furthermore, supplementing arginine to the diet of pregnant gilts between days 30 and 114 of gestation increases the number of live-born piglets and litter birth-weight. Availability of feed-grade functional AA holds great promise for improving animal health and nutrient utilization in pig production worldwide. Additionally, feedstuffs of animal origin [e.g., blood meal (ring dried), feather meal (hydrolyzed), meat and bone meal, porcine protein meal, and poultry by-product meal (both feed- and petfood-grades)] are excellent and cost-effective sources of both essential and functional AA for formulating balanced swine diets. New knowledge on AA nutrition provides a much needed scientific basis for revising the next edition of swine nutrient requirements.