title: Supplementation of branched-chain amino acids to a reduced-protein diet improves growth performance in piglets: involvement of increased feed intake and direct muscle growth-promoting effect.
abstract: The aim of this study was to investigate whether supplementing branched-chain amino acids (AA) (BCAA) along with a reduced-protein diet increases piglet growth, and whether elevated feed intake and muscle growth-promoting effect contribute to this improvement. In Expt 1, twenty-eight weanling piglets were randomly fed one of the following four diets: a positive control (PC) diet, a reduced-protein negative control (NC) diet, an NC diet supplemented with BCAA to the same levels as in the PC diet (test 1 (T1)) and an NC diet supplemented with a 2-fold dose of BCAA in T1 diet (test 2 (T2)) for 28 d. In Expt 2, twenty-one weanling piglets were randomly assigned to NC, T1 and pair-fed T1 (P) groups. NC and T1 diets were the same as in Expt 1, whereas piglets in the P group were individually pair-fed with the NC group. In Expt 1, the NC group had reduced piglet growth and feed intake compared with the PC group, which were restored in T1 and T2 groups, but no differences were detected between T1 and T2 groups. In Expt 2, T1 and P groups showed increases in growth and mass of some muscles compared with the NC group. Increased feed intake after BCAA supplementation was associated with increased mRNA expressions of agouti-related peptide and co-express neuropeptide Y (NPY) and phosphorylation of mammalian target of rapamycin (mTOR) and ribosomal protein S6 kinase 1 (S6K1), as well as decreased mRNA expressions of melanocortin-4 receptor and cocaine- and amphetamine-regulated transcript and phosphorylation of eukaryotic initiation factor 2α in the hypothalamus. No differences were observed among PC, T1 and T2 groups except for higher NPY mRNA expression in the T2 group than in the PC group (Expt 1). Phosphorylation of mTOR and S6K1 in muscle was enhanced after BCAA supplementation, which was independent of change in feed intake (Expt 2). In conclusion, supplementing BCAA to reduced-protein diets increases feed intake and muscle mass, and contributes to better growth performance in piglets.
authors.affiliation: 1Department of Animal Nutrition and Feed Science,College of Animal Science and Technology,Huazhong Agricultural University,Wuhan 430070,People's Republic of China.
authors.forename: Liufeng
authors.initials: L
authors.lastname: Zheng
authors.affiliation: 1Department of Animal Nutrition and Feed Science,College of Animal Science and Technology,Huazhong Agricultural University,Wuhan 430070,People's Republic of China.
authors.forename: Hongkui
authors.initials: H
authors.lastname: Wei
authors.affiliation: 1Department of Animal Nutrition and Feed Science,College of Animal Science and Technology,Huazhong Agricultural University,Wuhan 430070,People's Republic of China.
authors.forename: Chuanshang
authors.initials: C
authors.lastname: Cheng
authors.affiliation: 1Department of Animal Nutrition and Feed Science,College of Animal Science and Technology,Huazhong Agricultural University,Wuhan 430070,People's Republic of China.
authors.forename: Quanhang
authors.initials: Q
authors.lastname: Xiang
authors.affiliation: 1Department of Animal Nutrition and Feed Science,College of Animal Science and Technology,Huazhong Agricultural University,Wuhan 430070,People's Republic of China.
authors.forename: Jiaman
authors.initials: J
authors.lastname: Pang
authors.affiliation: 1Department of Animal Nutrition and Feed Science,College of Animal Science and Technology,Huazhong Agricultural University,Wuhan 430070,People's Republic of China.
authors.forename: Jian
authors.initials: J
authors.lastname: Peng
mesh_terms: D000597:Amino Acids, Branched-Chain / Q000494:pharmacology*; D000821:Animal Feed; D000822:Animal Husbandry; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001066:Appetite / Q000235:genetics; D001921:Brain / Q000378:metabolism; D018753:Diet, Protein-Restricted; D019587:Dietary Supplements; D004435:Eating / Q000187:drug effects*; D002149:Energy Intake / Q000187:drug effects*; D008297:Male; D009132:Muscles / Q000187:drug effects* / Q000378:metabolism; D011897:Random Allocation; D013552:Swine / Q000254:growth & development*; D014886:Weaning; D015430:Weight Gain
chemical_list: D000597:Amino Acids, Branched-Chain
keywords: AA amino acids; ADFI average daily feed intake; ADG average daily gain; BCAA branched-chain AA; BW body weight; Branched-chain amino acids; CART cocaine- and amphetamine-regulated transcript; CP crude protein; Feed intakes; G:F gain:feed intake; GAAC general amino acids control; Growth performance; LD 
                    longissimus dorsi; MC4R melanocortin-4 receptor; Muscle mass; NC reduced-protein negative control; NPY co-express neuropeptide Y; P pair-fed T1; PC positive control; Piglets; S6K1 ribosomal protein S6 kinase 1; T1 test 1; T2 test 2; eIF2α
                  eukaryotic initiation factor 2α; mTOR mammalian target of rapamycin