畜牧兽医学报  2021, Vol. 52 Issue (1): 126-134. DOI: 10.11843/j.issn.0366-6964.2021.013    PDF    
妊娠早期饲粮添加不同水平N-氨甲酰谷氨酸改善母羊产羔性能的研究
蔡元1, 田见晖2, 王栋3, 罗玉柱4, 翁士乔5, 李春阳1     
1. 西北民族大学生命科学与工程学院, 兰州 730030;
2. 中国农业大学动物科学技术学院, 北京 100193;
3. 中国农业科学院北京畜牧兽医研究所, 北京 100193;
4. 甘肃农业大学动物科学技术学院, 兰州 730070;
5. 宁波三生生物科技有限公司, 宁波 315100
摘要:旨在研究妊娠早期饲喂不同水平N-氨甲酰谷氨酸(N-carbamylglutamate,NCG)对母羊产羔性能及相关血液指标的影响。选用2~3胎次湖羊160只,随机分为4组,每组40只母羊,自配种当天(记为妊娠第0天)开始,分别饲喂基础饲粮(对照组)、基础饲粮+0.05% NCG、基础饲粮+0.08% NCG、基础饲粮+0.11% NCG,40 d后均饲喂基础饲粮。测定母羊产羔性能和妊娠第0、20、40天母羊血浆中游离氨基酸、总一氧化氮合酶(TNOS)、诱导型一氧化氮合酶(iNOS)、一氧化氮(NO)、生长激素、雌二醇、孕酮、尿素和氨浓度。结果显示,0.08%和0.11% NCG组产羔性能显著提高,两组的窝产羔数和窝产活羔数较对照组显著增加(P < 0.05),但活羔初生个体重显著降低(P < 0.05);各NCG组妊娠第40天NO浓度显著升高(P < 0.05),0.11% NCG组妊娠第40天iNOS浓度和妊娠第20天孕酮浓度较对照组显著升高(P < 0.05);0.08%和0.11% NCG组妊娠第20天氨浓度显著低于对照组和0.05% NCG组(P < 0.05),0.11% NCG组妊娠第40天氨浓度显著低于对照组(P < 0.05)。综上,妊娠早期母羊饲粮添加NCG可提高母羊体循环iNOS、NO和孕酮浓度,改善胎盘营养与妊娠维持状态;降低血浆氨浓度,提高胎儿发育环境安全性,改善母羊产羔性能,提高母羊窝产羔数和窝产活羔数。
关键词N-氨甲酰谷氨酸    经产母羊    产羔性能    血液指标    
Effects of Dietary N-carbamylglutamate Supplementation on Improving Lambing Performance of Ewes during Early Pregnancy
CAI Yuan1, TIAN Jianhui2, WANG Dong3, LUO Yuzhu4, WENG Shiqiao5, LI Chunyang1     
1. Life Science and Engineering College of Northwest Minzu University, Lanzhou 730030, China;
2. College of Animal Science and Technology, China Agricultural University, Beijing 100193, China;
3. Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China;
4. College of Animal Science and Technology, Gansu Agricultural University, Lanzhou 730070, China;
5. Ningbo Sansheng Biotechnology Co., Ltd., Ningbo 315100, China
Abstract: The aim of the present study is to investigate the effects of dietary N-carbamylglutamate (NCG) supplementation on lambing performance and blood indexes of ewes during early pregnancy. A total of 160 second- and third-parity Hu sheep were randomly assigned into 4 groups which fed with basal diet(control group), basal diet supplemented with 0.05%, 0.08% and 0.11%NCG, respectively. Sheep were fed with experimental diets for 40 days from the day of mating. After that, all sheep were fed with basal diet. The parameters of lambing performance were recorded immediately after farrowing. The plasma amino acids, total nitric oxide synthase (TNOS), inducible nitric oxide synthase (iNOS), nitric oxide (NO), growth hormone, estradiol, progesterone, urea and ammonia were detected on the day 0, 20 and 40 of pregnancy. The results showed that the dietary supplementation of 0.08% and 0.11%NCG significantly increased the number of total lambs and total live lambs per litter compared with the control group(P < 0.05), but the birth weight of lamb born alive decreased significantly (P < 0.05). On day 40 of pregnancy, the plasma concentration of NO in NCG-supplemented groups were significantly higher than that of control group(P < 0.05). In addition, compared to control group, 0.11% NCG-supplemented group had higher plasma concentration of iNOS on day 40 of pregnancy (P < 0.05), as well as higher plasma concentration of progesterone on day 20 of pregnancy (P < 0.05). Moreover, both 0.08% and 0.11% NCG -supplemented groups had lower level of plasma ammonia than those in control group and 0.05% NCG-supplemented group on day 20 of pregnancy (P < 0.05), and on day 40 of pregnancy the plasma ammonia in 0.11% NCG-supplemented group was significantly lower than that of control group (P < 0.05). The results suggested that dietary NCG supplementation during the early stage of pregnancy increased plasma concentration of iNOS, NO and progesterone, and thus improved placental nutrition and pregnancy maintenance. The reduced plasma concentration of ammonia by NCG supplementation, may improve the lambing performance by optimizing the uterine environment and enhancing fetal developmental potential.
Key words: N-carbamylglutamate    multiparous ewes    lambing performance    blood indexes    

绵羊(Ovis aries)产羔数是影响养羊业发展的关键因素,产羔数的增加对于养羊经济效益的提高具有重要意义。胚胎产前损失是哺乳动物繁殖过程中的一个主要问题,绵羊和大多数哺乳动物胚胎死亡率约20%~40%,其中三分之二发生在附植期[1]。目前,尚无有效方法减少早期妊娠胚胎损失,严重制约了家畜繁殖性能的发挥。母体营养是影响子宫内环境的主要因素,在调节胎儿存活、生长和发育中起重要作用。其中,营养的均衡性和质量都可能影响到胚胎发育。研究表明,精氨酸是体内合成一氧化氮(nitric oxide,NO)、蛋白质等物质的前体,能够调控胎盘的营养运输,促进胎盘和胎儿发育[2],精氨酸通过内皮型一氧化氮合酶(endothelial nitric oxide synthase, eNOS)和诱导型一氧化氮合酶(inducible nitric oxide synthase, iNOS)合成的NO对胚胎发育、着床和滋养层侵入、胎盘血管生成具有积极的调控作用[3-7]。鉴于精氨酸对胚胎发育的重要促进机制,很多研究在饲料中添加N-乙酰谷氨酸(N-acetylglutamate,NAG)的类似物[8]N-氨甲酰谷氨酸(N-carbamylglutamate,NCG),以激活精氨酸内源合成的必需辅助因子氨甲酰磷酸合成酶-Ⅰ(Carbamyl phosphate synthetase Ⅰ, CPS-Ⅰ),促进精氨酸内源合成[9]。通过妊娠饲粮中添加NCG提高了胚胎存活率,显著改善了母猪繁殖性能[10-11],NCG还能降低过高血浆氨导致的胚胎和胎儿死亡风险[12]。有研究曾对限饲母羊补饲NCG,使胎盘肉阜和子叶组织中Tie-2 mRNA表达量、p-p70S6K蛋白表达量和脐静脉血中的NO浓度显著升高,进而促进了胎盘生长发育[13],NCG添加还促进了营养不良母羊的胎儿生长[14-15],但目前还未见母羊妊娠早期饲喂NCG效果的相关报道。为此,本研究拟在经产母羊妊娠早期饲粮中添加不同水平NCG,探索其对产羔性能的影响,以期为提高养羊业经济效益提供技术支持。

1 材料与方法 1.1 试验材料

NCG的有效含量为97%,由国家饲料工程技术研究中心生产。

1.2 试验动物与试验设计

选择160只2~3岁、胎次(2~3胎)和体重相近(约60 kg)、繁殖机能正常的湖羊母羊,随机分为4组,每组40只,每只母羊为1个重复。参照NRC(2004)标准,根据相应体重母绵羊妊娠前期营养需要量配制基础饲粮(表 1)。精料和粗饲料混合饲喂,对照组每只羊每天饲喂2.7 kg,其中精料0.162 kg、大麦草0.621 kg、苜蓿草0.135 kg、玉米青贮1.782 kg。以饲喂基础饲粮的为对照组,饲喂在基础饲粮中分别添加0.05%、0.08%和0.11%NCG的为试验组。配种公羊为澳洲白,母羊采用同期排卵-子宫角定时输精方式配种,腹腔镜子宫角输精1次,自配种当天(计为妊娠第0天)开始进行饲喂试验,饲喂40 d后,各组均饲喂基础饲粮,直到分娩。

表 1 饲粮组成和营养水平(干物质基础) Table 1 Composition and nutrient levels of diets (dry matter basis) 
1.3 饲养管理及样品采集

试验在甘肃武威普康集团进行。各组根据试验设计饲喂日粮,每天分08:30和16:00两次饲喂。保证舍内清洁干燥、通风良好、温度适宜,并进行常规清洁和定时消毒。在妊娠第0、20、40天上午8:00,每组选择10只母羊空腹颈静脉采血10 mL,置于有肝素钠的离心管内,混匀,静置20 min,4 ℃ 3 000×g离心10 min分离血浆样品,将血浆分装于1 mL的离心管,-20 ℃冻存,用于测定血浆中氨基酸、尿素、TNOS、iNOS、NO、生长激素、雌二醇、孕酮和氨的浓度。

1.4 测定指标及方法

1.4.1 母羊产羔性能   记录窝产羔羊数、窝产活羔数、死羔数、羔羊初生重等指标。

1.4.2 血浆氨基酸浓度的测定   采用德国赛卡姆Sykam(S-433D)(德国赛卡姆公司)氨基酸自动分析仪,测定血浆氨基酸浓度。取0.5 mL血浆样品与10%磺基水杨酸按1:3比例稀释,高速振荡1 min,冰上静置15 min,4 ℃ 10 000×g离心15 min,取上清液过滤装瓶, 上机测定氨基酸浓度。

1.4.3 血浆TNOS、iNOS、NO、氨、尿素、生长激素、雌二醇和孕酮浓度的测定   用比色法测定TNOS、iNOS、NO、尿素和氨的浓度,用酶联免疫吸附法(ELISA)测定生长激素、雌二醇和孕酮浓度,均按试剂盒操作说明进行各指标测定。TNOS、iNOS、NO和氨试剂盒均购自南京建成生物工程研究所;尿素、生长激素、雌二醇和孕酮检测试剂盒均购自江苏宝莱生物科技有限公司。

1.5 数据处理

剔除试验期间掉栓、返情、空怀的试验羊,4个处理组实际分娩母羊的数量分别为22、21、22和22只。用SPSS 23.0统计软件对试验数据进行单因素方差分析(one-way ANOVA),以P < 0.05作为显著性判断标准,所有数据均以“平均值±标准误”表示。

2 结果 2.1 妊娠早期饲粮中添加NCG对母羊产羔性能的影响

表 2所示,与对照组相比,添加0.08%和0.11%NCG组,母羊窝产羔分别提高0.64(P < 0.05)和0.59只(P < 0.05);窝产活羔数分别提高0.59(P < 0.05)和0.68只(P < 0.05);活羔初生个体重分别减少0.73(P < 0.05)和0.78 kg(P < 0.05),但活羔初生窝重提高不显著(P>0.05)。对照组2只母羊各产1只死胎,0.08%NCG组1只母羊产3只死胎。说明妊娠早期添加0.08%和0.11%NCG,能显著增加湖羊窝产羔数,改善湖羊产羔性能。

表 2 妊娠早期饲粮中添加NCG对母羊产羔性能的影响 Table 2 Effects of different dietary NCG supplementation on the lambing performance of ewes during early pregnancy
2.2 妊娠早期饲粮中添加NCG对母羊血浆游离氨基酸浓度的影响

表 3所示,添加NCG对妊娠20和40 d母羊血浆游离氨基酸浓度影响不显著(P>0.05),但血浆精氨酸浓度随NCG增加呈逐渐升高趋势; 妊娠40 d时,血浆脯氨酸浓度随NCG添加量增加呈升高趋势。说明绵羊妊娠早期饲粮中添加NCG后血浆精氨酸和脯氨酸浓度有逐渐升高趋势。

表 3 妊娠早期饲粮中添加NCG对母羊血浆游离氨基酸浓度的影响 Table 3 Effects of different dietary NCG supplementation on the concentration of free amino acids in plasma of ewes during early pregnancy  
2.3 妊娠早期饲粮中添加NCG对母羊血浆NO、TNOS、iNOS浓度的影响

表 4所示,妊娠第40天时,0.05%、0.08%和0.11%NCG组NO浓度显著高于对照组(P < 0.05),各添加组间差异不显著(P>0.05);0.05%、0.08%和0.11%NCG组TNOS浓度比对照组高,但差异不显著(P>0.05);0.11%NCG组的iNOS浓度显著高于对照组(P < 0.05),其余各组差异不显著(P>0.05)。说明妊娠早期添加0.11%NCG,能够显著增加妊娠第40天绵羊血浆NO和iNOS的浓度。

表 4 妊娠早期饲粮中添加NCG对母羊血浆NO、TNOS、iNOS浓度的影响 Table 4 Effects of different dietary NCG supplementation on the concentrations of NO, TNOS and iNOS in plasma of ewes during early pregnancy
2.4 妊娠早期饲粮中添加NCG对母羊血浆激素浓度的影响

表 5所示,添加NCG对生长激素和雌二醇影响不显著(P>0.05);0.11%NCG组妊娠第20天孕酮浓度比对照组高223.41 pmol·L-1(P < 0.05),其余各组间孕酮浓度差异不显著(P>0.05)。说明妊娠早期添加0.11%NCG,能够显著增加妊娠第20天绵羊血浆孕酮的浓度。

表 5 妊娠早期饲粮中添加NCG对母羊血浆激素浓度的影响 Table 5 Effects of different dietary NCG supplementation on the concentrations of hormone in plasma of ewes during early pregnancy
2.5 妊娠早期饲粮中添加NCG对母羊血浆尿素和氨浓度的影响

表 6所示,添加NCG对血浆尿素浓度影响不显著(P>0.05),0.08%和0.11%NCG组,妊娠第20天氨浓度显著低于对照组和0.05%NCG组(P < 0.05),0.11%NCG组妊娠第40天血氨浓度显著低于对照组(P < 0.05),其余各组间差异不显著(P>0.05)。说明妊娠早期添加NCG,能够显著降低妊娠第20天0.08%和0.11%NCG组及妊娠第40天0.11%NCG组绵羊血浆氨的浓度。

表 6 妊娠早期饲粮中添加NCG对母羊血浆尿素和氨浓度的影响 Table 6 Effects of different dietary NCG supplementation on the concentrations of urea and ammonia in plasma of ewes during early pregnancy
3 讨论 3.1 添加NCG对母羊产羔性能的影响

本研究表明,妊娠早期添加NCG,能增加母羊窝产羔数、窝产活羔数,改善湖羊产羔性能。母体营养是影响子宫内环境最主要的因素,母体营养不足和营养过剩都会降低胎盘-胎儿血流量,影响胎儿的生长发育和存活[16],尤其在着床期和胎盘发育期,胎儿发育最容易受到蛋白质缺乏的影响,适宜的营养是提高胚胎存活率和促进胎儿生长发育的首要因素[10, 17]。NCG作为精氨酸内源合成关键酶CPS-Ⅰ的激活剂,在体内能促进精氨酸合成,在动物机体中发挥多种有益作用,如促进血管生成、改善氮代谢、促进泌乳和生长、增强动物繁殖和免疫能力[18],尤其是能促进绵羊滋养外胚层细胞系增殖、迁移和蛋白质合成[19-20],减少多胎母羊胚胎损失,增加羔羊出生体重,提高胎羔成活率[21-22]。经产母猪整个妊娠期饲粮添加0.1%NCG,窝产活仔数提高0.55头,仔猪初生窝重提高1.39 kg,初生个体重提高70 g,90 d血浆脯氨酸浓度显著升高[12],妊娠早期母猪饲粮添加NCG,显著增加了窝产活仔数[11]。本试验首次在湖羊妊娠早期添加NCG,也显著改善了母羊产羔性能。

此外,本研究中添加NCG虽然提高了窝重,但0.08%和0.11%NCG组活羔初生个体重显著降低,主要原因是添加NCG使产羔数显著增加, 由于总营养的限制性和个体的营养竞争作用,导致活羔初生个体重显著降低;同时,经产母猪中一般在整个妊娠期[12]或妊娠后期[23]添加NCG,增加了仔猪数量,促进了胎儿的发育,本研究为减少早期妊娠胚胎损失,提高绵羊的产羔性能,在妊娠早期添加NCG,活羔初生个体重在3.6 kg以上,达到了一般羊场羔羊初生重为1.8 kg以上的健康标准。

3.2 添加NCG对母羊血浆NO和iNOS浓度的影响

本研究发现,0.05%、0.08%、0.11%NCG组在妊娠第40天时血浆NO显著升高,有研究报道,添加NCG提高了妊娠母猪血浆NO含量[2, 12, 23],限饲母羊补饲0.1%NCG使脐静脉血中的NO浓度显著升高,进而促进了胎盘生长发育[13],和本研究结果一致。动物体内的NO是由精氨酸在NOS参与下合成[3],NO是一种重要的内皮源性舒张因子,通过调控胎盘-胎儿间血流,在母体向胎儿提供养分和氧气的过程中发挥重要的调控作用[24],还通过重构细胞外基质调节胚胎着床[25],为胎儿在子宫中的发育提供大量营养素[26],在胎盘血管发育中起重要作用[4],血管生成的起始需要VEGF的表达[27],其有丝分裂效应由NO介导[28-29],NO可诱导来自不同血管床的胎儿内皮细胞增殖[30-31],并调节中心血管口径[32]。大量的证据表明,NO是胎盘血管生成、胚胎发育以及胎盘和胎儿生长的重要调控因子[27-32]。妊娠早期NO浓度升高促进了胎盘发育,同时也提高了胚胎的存活和着床率,这可能是妊娠早期添加NCG增加绵羊产羔数的作用机理。妊娠0~28 d的母猪饲粮添加NCG,促进了胚胎存活和发育,使妊娠第28天的总胎和活胎数显著增加,死亡率显著降低[10],这一结果支持了本试验对产羔数增加作用机理的推测。此外,Liu等[33]研究表明,NCG可能通过microRNAs调控NOS和血管内皮生长因子等活性,这进一步印证了本试验中添加NCG提高iNOS浓度的结果,也为本研究结果给出了科学合理的解释。

3.3 添加NCG对母羊血浆激素水平的影响

雌激素和孕激素是调控妊娠的主要激素,它们在卵细胞的生殖道转运、内皮细胞增殖和分化、子宫内皮细胞蜕膜化以及在胚胎着床过程中,都扮演着重要的调控角色,对哺乳动物妊娠的建立和维持起着至关重要的作用。本试验在妊娠早期饲粮中添加NCG,提高了妊娠第20天的血液孕酮浓度,尤其0.11%NCG组在妊娠第20天的血浆孕酮显著增加,因精氨酸也是一种激素促分泌素,能够促进胰岛素、生长激素等激素的合成与分泌[26, 34]。妊娠初期,孕激素能促进子宫内膜增生,使腺体发育、功能增强,从而有利于胚胎附植[35],此阶段孕酮浓度的升高,可能也是添加NCG增加产羔数的原因之一。

3.4 添加NCG对母羊血浆氨浓度的影响

经产母猪整个妊娠期饲粮中添加0.1%NCG后,血浆尿素和氨浓度降低[12],本试验中添加NCG组母羊血浆尿素浓度没有明显变化,其原因可能是物种不同。在饲粮中添加NCG能够提高中国荷斯坦奶牛产奶量、显著增加血浆NO水平、降低血浆氨水平、提高氮的利用率[36]。在人类医学中,NCG已被应用于临床进行代谢疾病的治疗,用NCG处理后,血浆氨和谷氨酰胺水平明显降低[37],血浆氨浓度降低有利于胚胎和胎儿的存活[12]。本试验中添加NCG也降低了母羊血浆氨浓度,说明绵羊饲粮中添加NCG提高了氮的利用率,也为胎儿提供了更安全的发育环境。

4 结论

妊娠早期母羊饲粮添加NCG可提高母羊体循环iNOS、NO和孕酮浓度,改善胎盘营养与妊娠维持状态;降低血浆氨浓度,提高胎儿发育环境安全性,改善母羊产羔性能,提高母羊窝产羔数和窝产活羔数。

参考文献
[1] BAZER F W, FIRST N L. Pregnancy and parturition[J]. J Anim Sci, 1983, 57(Suppl 2): 425–460.
[2] ZHANG H, SUN L W, WANG Z Y, et al. N-carbamylglutamate and L-arginine improved maternal and placental development in underfed ewes[J]. Reproduction, 2016, 151(6): 623–635. DOI: 10.1530/REP-16-0067
[3] ROSSELLI M, KELLER R J, DUBEY R K. Role of nitric oxide in the biology, physiology and path-ophysiology of reproduction[J]. Hum Reprod Update, 1998, 4(1): 3–24. DOI: 10.1093/humupd/4.1.3
[4] KRAUSE B J, HANSON M A, CASANELLO P. Role of nitric oxide in placental vascular development and function[J]. Placenta, 2011, 32(11): 797–805. DOI: 10.1016/j.placenta.2011.06.025
[5] KAUFMANN P, BLACK S, HUPPERTZ B. Endovascular trophoblast invasion:implications for the pathogenesis of intrauterine growth retardation and preeclampsia[J]. Biol Reprod, 2003, 69(1): 1–7. DOI: 10.1095/biolreprod.102.014977
[6] AYLING L J, WHITLEY G S J, APLIN J D, et al. Dimethylarginine dimethylaminohydrolase (DDAH) regulates trophoblast invasion and motility through effects on nitric oxide[J]. Hum Reprod, 2006, 21(10): 2530–2537. DOI: 10.1093/humrep/del111
[7] HARRIS L K, MCCORMICK J, CARTWRIGHT J E, et al. S-nitrosylation of proteins at the leading edge of migrating trophoblasts by inducible nitric oxide synthase promotes trophoblast invasion[J]. Exp Cell Res, 2008, 314(8): 1765–1776. DOI: 10.1016/j.yexcr.2008.02.010
[8] GESSLER P, BUCHAL P, SCHWENK H U, et al. Favourable long-term outcome after immediate treatment of neonatal hyperammonemia due to N-acetylglutamate synthase deficiency[J]. Eur J Pediatr, 2010, 169(2): 197–199. DOI: 10.1007/s00431-009-1006-0
[9] MORIZONO H, CALDOVIC L, SHI D S, et al. Mammalian N-acetylglutamate synthase[J]. Mol Genet Metab, 2004, 81 Suppl 1(S1): 4–11.
[10] ZHU J L, ZENG X F, PENG Q, et al. Maternal N-carbamylglutamate supplementation during early pregnancy enhances embryonic survival and develop-ment through modulation of the endometrial proteome in gilts[J]. J Nutr, 2015, 145(10): 2212–2220. DOI: 10.3945/jn.115.216333
[11] CAI S, ZHU J L, ZENG X Z, et al. Maternal N-carbamylglutamate supply during early pregnancy enhanced pregnancy outcomes in sows through modulations of targeted genes and metabolism pathways[J]. J Agric Food Chem, 2018, 66(23): 5845–5852. DOI: 10.1021/acs.jafc.8b01637
[12] 江雪梅, 吴德, 方正锋, 等. 饲粮添加L-精氨酸或N-氨甲酰谷氨酸对经产母猪繁殖性能及血液参数的影响[J]. 动物营养学报, 2011, 23(7): 1185–1193.
JIANG X M, WU D, FANG Z F, et al. Effects of dietary L-arginine or N-carbamylglutamate on reproductive performance and blood parameters of multiparous sows[J]. Chinese Journal of Animal Nutrition, 2011, 23(7): 1185–1193. DOI: 10.3969/j.issn.1006-267x.2011.07.017 (in Chinese)
[13] 孙玲伟, 王智博, 安世钰, 等. RP-Arg和NCG对营养限饲湖羊胎盘发育的影响[J]. 南京农业大学学报, 2020, 43(1): 125–133.
SUN L W, WANG Z B, AN S Y, et al. Effects of dietary RP-Arg and NCG supplementation on development of maternal and fetal placenta in nutrient restriction Hu sheep during pregnancy[J]. Journal of Nanjing Agricultural University, 2020, 43(1): 125–133. (in Chinese)
[14] SUN L W, ZHANG H, WANG Z Y, et al. Dietary rumen-protected arginine and N-carbamylglutamate supplementation enhances fetal growth in underfed ewes[J]. Reprod Fertil Dev, 2018, 30(8): 1116–1127.
[15] ZHANG H, SUN L W, WANG Z Y, et al. Dietary N-carbamylglutamate and rumen-protected L-arginine supplementation ameliorate fetal growth restriction in undernourished ewes[J]. J Anim Sci, 2016, 94(5): 2072–2085. DOI: 10.2527/jas.2015-9587
[16] WU G Y, BAZER F W, CUDD T A, et al. Maternal nutrition and fetal development[J]. J Nutr, 2004, 134(9): 2169–2172. DOI: 10.1093/jn/134.9.2169
[17] WU G Y, POND W G, OTT T, et al. Maternal dietary protein deficiency decreases amino acid concentrations in fetal plasma and allantoic fluid of pigs[J]. J Nutr, 1998, 128(5): 894–902. DOI: 10.1093/jn/128.5.894
[18] CHACHER B, LIU H Y, WANG D M, et al. Potential role of N-carbamoyl glutamate in biosynthesis of arginine and its significance in production of ruminant animals[J]. J Anim Sci Biotechnol, 2013, 4(1): 16.
[19] KIM J Y, BURGHARDT R C, WU G Y, et al. Select nutrients in the ovine uterine lumen.Ⅶ.Effects of arginine, leucine, glutamine, and glucose on trophectoderm cell signaling, proliferation, and migration[J]. Biol Reprod, 2011, 84(1): 62–69.
[20] KIM J Y, BURGHARDT R C, WU G Y, et al. Select nutrients in the ovine uterine lumen.Ⅷ.Arginine stimulates proliferation of ovine trophectoderm cells through MTOR-RPS6K-RPS6 signaling cascade and synthesis of nitric oxide and polyamines[J]. Biol Reprod, 2011, 84(1): 70–78.
[21] LASSALA A, BAZER F W, CUDD T A, et al. Parenteral administration of L-arginine prevents fetal growth restriction in undernourished ewes[J]. J Nutr, 2010, 140(7): 1242–1248.
[22] LASSALA A, BAZER F W, CUDD T A, et al. Parenteral administration of L-arginine enhances fetal survival and growth in sheep carrying multiple fetuses[J]. J Nutr, 2011, 141(5): 849–855.
[23] 刘星达, 吴信, 印遇龙, 等. 妊娠后期日粮中添加不同水平N-氨甲酰谷氨酸对母猪繁殖性能的影响[J]. 畜牧兽医学报, 2011, 42(11): 1550–1555.
LIU X D, WU X, YIN Y L, et al. Effects of different dietary N-carbamylglutamate supplementation on the reproductive performance of sows during late pregnancy[J]. Acta Veterinaria et Zootechnica Sinica, 2011, 42(11): 1550–1555. (in Chinese)
[24] BIRD I M, ZHANG L B, MAGNESS R R. Possible mechanisms underlying pregnancy-induced changes in uterine artery endothelial function[J]. Am J Physiol Regul Integr Comp Physiol, 2003, 284(2): R245–R258.
[25] HANSSON S R, NÄÄV Å, ERLANDSSON L. Oxidative stress in preeclampsia and the role of free fetal hemoglobin[J]. Front Physiol, 2015, 5: 516.
[26] WU G Y, BAZER F W, DAVIS T A, et al. Important roles for the arginine family of amino acids in swine nutrition and production[J]. Livest Sci, 2007, 112(1-2): 8–22.
[27] SHALABY F, ROSSANT J, YAMAGUCHI T P, et al. Failure of blood-island formation and vasculogenesis in Flk-1-deficient mice[J]. Nature, 1995, 376(6535): 62–66.
[28] PARENTI A, MORBIDELLI L, CUI X L, et al. Nitric oxide is an upstream signal of vascular endothelial growth factor-induced extracellular signal-regulated kinase activation in postcapillary endothelium[J]. J Biol Chem, 1998, 273(7): 4220–4226.
[29] SHIZUKUDA Y, TANG S Q, YOKOTA R, et al. Vascular endothelial growth factor-induced endothe-lial cell migration and proliferation depend on a nitric oxide-mediated decrease in protein kinase Cδ activity[J]. Circ Res, 1999, 85(3): 247–256.
[30] ZHENG J, WEN Y X, AUSTIN J L, et al. Exogenous nitric oxide stimulates cell proliferation via activation of a mitogen-activated protein kinase pathway in ovine fetoplacental artery endothelial cells[J]. Biol Reprod, 2006, 74(2): 375–382. DOI: 10.1095/biolreprod.105.043190
[31] GIEN J, SEEDORF G J, BALASUBRAMANIAM V, et al. Intrauterine pulmonary hypertension impairs angiogenesis in vitro:role of vascular endothelial growth factor-nitric oxide signaling[J]. Am J Respir Crit Care Med, 2007, 176(11): 1146–1153. DOI: 10.1164/rccm.200705-750OC
[32] BUSTAMANTE S A, PANG Y, ROMERO S, et al. Inducible nitric oxide synthase and the regulation of central vessel caliber in the fetal rat[J]. Circulation, 1996, 94(8): 1948–1953. DOI: 10.1161/01.CIR.94.8.1948
[33] LIU X D, WU X, YIN Y L, et al. Effects of dietary L-arginine or N-carbamylglutamate supplementation during late gestation of sows on the miR-15b/16, miR-221/222, VEGFA and eNOS expression in umbilical vein[J]. Amino Acids, 2012, 42(6): 2111–2119. DOI: 10.1007/s00726-011-0948-5
[34] NEWSHOLME P, BRENNAN L, RUBI B, et al. New insights into amino acid metabolism, β-cell function and diabetes[J]. Clin Sci (Lond), 2005, 108(3): 185–194. DOI: 10.1042/CS20040290
[35] 朱士恩. 家畜繁殖学[M]. 6版. 北京: 中国农业出版社, 2015: 47.
ZHU S E. Animal reproduction[M]. 6th ed. Beijing: China Agriculture Press, 2015: 47. (in Chinese)
[36] CHACHER B, ZHU W, YE J A, et al. Effect of dietary N-carbamoylglutamate on milk production and nitrogen utilization in high-yielding dairy cows[J]. J Dairy Sci, 2014, 97(4): 2338–2345. DOI: 10.3168/jds.2013-7330
[37] TUCHMAN M, CALDOVIC L, DAIKHIN Y, et al. N-carbamylglutamate markedly enhances ureagenesis in N-acetylglutamate deficiency and propionic acidemia as measured by isotopic incorporation and blood biomarkers[J]. Pediatr Res, 2008, 64(2): 213–217. DOI: 10.1203/PDR.0b013e318179454b