Recent Advances in Swine Amino Acid Nutrition1

Recent advances in swine protein nutrition are characterized by the development of functional a- mino acids （AA） in regulating fetal and postnatal survival, growth and development. These AA include arginine, glutamine, glutamate, proline, leucine, cyste- ine 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 utili- zation by pigs. The underlying mechanisms include activation of nitric oxide, mammalian target of rapam- ycin, gaseous signaling, and AMP-activated protein ki- nase pathways, as well as anti-oxidative function. Di- etary supplementation with arginine, glutamine, pro- line or leucine to weanling piglets enhances theirgrowth performance. Arginine or glutamine is also ef- fective 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. Addi- tionally, feedstuffs of animal origin [ e. g. , blood meal （ ring dried ）, feather meal （ hydrolyzed ）, meat and bone meal, porcine protein meal, and poultry by-prod- uct meal （both feed- and petfood-grades） ] are excel- lent 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.