摘要
Background:Most embryonic loss in pigs occurs before d 30 of gestation.Dietary supplementation with L-arginine(Arg) during early gestation can enhance the survival and development of conceptuses(embryo/fetus and its extraembryonic membranes) in gilts.However,the underlying mechanisms remain largely unknown.Methods:Between d 14 and 30 of gestation,each gilt was fed daily 2 kg of a corn-and soybean-meal based diet(12% crude protein) supplemented with either 0.4% Arg(as Arg-HCl) or an isonitrogenous amount of L-alanine(Control).There were 10 gilts per treatment group.On d 30 of gestation,gilts were fed either Arg-HCl or L-alanine 30 min before they were hysterectomized,followed by the collection of placentae,embryos,fetal membranes,and fetal fluids.Amniotic and allantoic fluids were analyzed for nitrite and nitrate [NOx;stable oxidation products of nitric oxide(NO)],polyamines,and amino acids.Placentae were analyzed for syntheses of NO and polyamines,water and amino acid transport,concentrations of amino acid-related metabolites,and the expression of angiogenic factors and aquaporins(AQPs).Results:Compared to the control group,Arg supplementation increased(P < 0.05) the number of viable fetuses by 1.9 per litter,the number and diameter of placental blood vessels(+ 25.9% and + 17.0% respectively),embryonic survival(+ 18.5%),total placental weight(+ 36.5%),the total weight of viable fetuses(+ 33.5%),fetal crown-to-rump length(+ 4.7%),and total allantoic and amniotic fluid volumes(+ 44.6% and + 75.5% respectively).Compared to control gilts,Arg supplementation increased(P < 0.05) placental activities of GTP cyclohydrolase-1(+ 33.1%) and ornithine decarboxylase(+ 29.3%);placental syntheses of NO(+ 26.2%) and polyamines(+ 28.9%);placental concentrations of NOx(+ 22.5%),tetrahydrobiopterin(+ 21.1%),polyamines(+ 20.4%),c AMP(+ 27.7%),and c GMP(+ 24.7%);total amounts of NOx(+ 61.7% to + 96.8%),polyamines(+ 60.7% to + 88.7%),amino acids(+ 39% to + 118%),glucose(+ 60.5% to + 62.6%),and fructose(+ 41.4% to + 57.0%) in fetal fluids;and the placental transport of water(+ 33.9%),Arg(+ 78.4%),glutamine(+ 89.9%),and glycine(+ 89.6%).Furthermore,Arg supplementation increased(P < 0.05) placental m RNA levels for angiogenic factors [VEGFA120(+ 117%),VEGFR1(+ 445%),VEGFR2(+ 373%),PGF(+ 197%),and GCH1(+ 126%)] and AQPs [AQP1(+ 280%),AQP3(+ 137%),AQP5(+ 172%),AQP8(+ 165%),and AQP9(+ 127%)].Conclusion:Supplementing 0.4% Arg to a conventional diet for gilts between d 14 and d 30 of gestation enhanced placental NO and polyamine syntheses,angiogenesis,and water and amino acid transport to improve conceptus development and survival.
基金
supported by Agriculture and Food Research Initiative Competitive Grant no.2014–05142 from the USDA National Institute of Food and Agriculture.
