氨基酸对妊娠母猪繁殖性能的影响及其作用机理

在所有的家畜中,猪的胎儿宫内发育迟缓(Intrauterine Growth Retardation,IUGR)问题最严重,其妊娠期胚胎及胎儿死亡率高达50%。胎盘功能不全是母猪繁殖性能不佳和仔猪初生重较低的主要原因。通过营养措施增强胎盘的生长和功能,可为提高胚胎和胎儿的存活及生长提供一种有效的解决方案。笔者发现,妊娠早期即胎盘生长最快的时期,母猪尿囊液(营养物质的储备库)所含氨基酸中精氨酸家族的含量出现不寻常的丰富。精氨酸通过代谢可生成鸟氨酸、脯氨酸和一氧化氮(NO),这些产物在体内发挥着许多重要的生理功能。更为重要的是,NO是血管舒张和血管生成因子,然而鸟氨酸和脯氨酸是胎盘合成多胺的底物,后者又是蛋白质合成和血管生成的重要调节物质。此外,精氨酸、亮氨酸、谷氨酰胺和脯氨酸可激活体内哺乳动物雷帕霉素靶蛋白(mTOR)信号通路,从而促进蛋白质合成和胎盘细胞生长。为了将有关氨基酸生物化学和营养的基础研究应用于生产实践,在小母猪妊娠的第14～28天或第30～114天,在其日粮中添加0.83%的L-精氨酸,结果母猪的产活仔数及其初生窝重均得到了提高。同时,在妊娠母猪日粮中添加0.4%L-精氨酸和0.6%L-谷氨酰胺,可提高营养物质的利用率,降低仔猪初生体重的个体差异,提高窝初生重。功能性氨基酸通过调节NO、多胺和蛋白质的合成,可刺激胎盘生长和母体营养物质通过胎盘向胎儿的转运,从而促进孕体的存活和生长发育。     

妊娠母猪背膘过厚影响繁殖性能的机制及其营养调控技术研究

母猪妊娠期的营养代谢,尤其是脂质代谢与体脂沉积存在密切关系。妊娠期母猪的脂质代谢特征,不仅决定了母猪妊娠期的体脂沉积规律,而且对仔猪初生性能和母猪泌乳性能产生关键的影响作用。值得注意的是,妊娠期母猪体脂的过度沉积,会引起胎盘脂质毒性,导致胎盘产生慢性炎症,提高了胎盘的氧化应激水平,从而阻碍胎盘的血管发育,导致弱仔的产生,使初生仔猪的初生重不均匀。另一方面,妊娠期体脂过度沉积时,妊娠后期血液中非酯化脂肪酸含量显著增加,从而导致系统性慢性炎症反应,是降低围产期机体的胰岛素敏感性的重要原因,并降低母猪泌乳期采食量。在母猪妊娠日粮中应用具有高水结合力、强吸水膨胀性和快速发酵特征的功能性纤维,不仅能提高限饲条件下妊娠母猪的饱腹感和饱感,并有效防止和改善母猪便秘;而且能调节肠道菌群组成,快速生成大量的短链脂肪酸,能有效改善母体的炎症状态,提高胰岛素敏感性。此外,所产生短链脂肪酸代谢后,能生成C15和C17等奇数碳链脂肪酸,也对提高母猪围产期胰岛素敏感性有重要作用。因此,控制妊娠期适宜的体脂沉积,是提高母猪繁殖性能和泌乳性能的关键控制点;在妊娠母猪日粮中合理运用功能性纤维,是调控母猪妊娠期体脂沉积有效的营养调控技术。     

精氨酸在猪生产中的研究进展

正精氨酸分子式为C_6H_(14)N_4O_2,分子量174.20,是动物体内一种重要的碱性氨基酸,主要以L-精氨酸的形式存在。精氨酸不仅作为合成蛋白质的原料,还通过多种酶参与到机体的代谢,并通过其代谢产物一氧化氮(NO)和多胺在调节妊娠期胎盘的形成、生长发育及胎儿的快速生长发育中发挥着重要的作用,是新生哺乳动物的必需     

硒对母猪氧化应激及其后代抗氧化能力的营养调控研究

硒作为的重要微量元素之一,可以通过胎盘和乳组织进行转移。仔猪可以从乳汁中获取硒源,提高硒含量,进而提高仔猪的初生重。同时,硒也能够调节母猪妊娠期间代谢速度,控制妊娠期自由基产生,进而提高胎盘输送营养功能。文章从母猪氧化应激体系角度来解析硒对母猪妊娠期氧化应激的调控机制、硒对哺乳母猪生产性能的调控作用。     

哺乳动物胎盘营养感应研究进展

妊娠期间母体营养的改变会影响胎儿的生长发育,而胎盘是母体-胎儿间进行气体、营养和代谢物交流的重要枢纽,哺乳动物胎盘营养感应系统响应母体和胎儿营养信号的变化,保证母体健康和胎儿生长发育。鉴于胎盘营养感应系统对哺乳动物繁育的重要性,本文从胎盘营养感应和胎盘养分分配方面综述了哺乳动物雷帕霉素靶蛋白(mammalian target of rapamycin,mTOR)、磷酸腺苷活化蛋白激酶(AMP-activated protein kinase,AMPK)、氨基己糖(Hexosamine)信号通路、糖原合成酶3(glycogen synthase kinase,GSK-3)、胰岛素/胰岛素样生长因子(insulin/insulin-like growth factor signaling pathway,IIS)等信号通路及其对妊娠期养分响应和对胎儿发育的影响,以期为哺乳动物的繁育提供参考依据。     

奶牛胎衣不下的临床诊治技术

牛分娩后经12h胎衣尚未排出,叫胎衣不下.胎衣不下可能是部分不下也可能是全部不下. 1 病因 1.1 胎盘分离障碍 1.1.1 胎盘未成熟这是发生流产的母牛胎衣不下的重要原因.胎盘平均在妊娠期满前2～5d成熟,成熟后胎盘的结缔组织胶原化,变湿润,易受分娩时的激素影响,母体胎盘和子体胎盘容易分离,未成熟的胎盘则缺乏上述变化.     

妊娠期日粮蛋白限饲对胎猪及胎盘抗氧化能力的影响

本研究旨在探索妊娠期饲喂不同蛋白水平日粮对胎盘抗氧化酶的活性和胎猪生长的影响。本试验以小梅山猪为动物模型,将20头纯种初产梅山母猪随机分为高蛋白组和低蛋白组。高蛋白组母猪在妊娠期给予粗蛋白含量为12%的日粮,低蛋白组给予粗蛋白含量为6%的日粮。在70胚龄时屠宰母猪,称量胎猪重和胎盘重,测定胎盘抗氧化主要指标:超氧化物歧化酶(SOD)、丙二醛(MDA)、总抗氧化能力(T-AOC)、谷胱甘肽过氧化物酶(GSH-Px)、过氧化氢酶(CAT);在出生时称量新生仔猪初生重。结果显示:低蛋白组胎猪重显著低于高蛋白组(P<0.05),两组胎盘重差异不显著;胎盘T-AOC低蛋白组极显著低于高蛋白组(P<0.01),GSH-Px低蛋白组显著低于高蛋白组(P<0.05),胎盘蛋白含量和SOD、MDA、CAT含量两组差异不显著(P>0.05);新生仔猪初生重低蛋白组显著低于高蛋白组(P<0.05)。以上结果提示:妊娠期母猪饲喂低蛋白日粮降低了胎盘抗氧化能力,导致胎猪重和新生仔猪重降低。     

家畜妊娠期母体的生理变化、妊娠诊断及直肠检查法

1母体生殖器官的变化 卵巢，妊娠期的卵巢变化主要表现有妊娠黄体存在。子宫，妊娠后随着胎儿的迅速发育，子宫变化显著，体积增大、位置下沉，母体胎盘的增长，血液供应增加，敏感性降低。子宫颈是妊娠期保证胎儿正常发育的重要门户，妊娠期母畜的子宫颈因阔约肌收缩而关闭得很紧，同时子宫黏膜上皮的单细胞腺管增生，分泌出浓稠的粘液称为子宫颈塞，堵塞于子宫颈管和子宫颈外口，将子宫颈管完全封闭起来。     

猪胎盘显微结构研究进展

胎盘是维系动物胎儿在子宫内正常发育的重要器官,胎盘性状的改变很大程度影响着多胎动物的繁殖效率。文章从绒毛膜/子宫内膜上皮双细胞层、血管和子宫腺体数量、母胎界面接触面积、绒毛晕等方面阐述不同妊娠期猪胎盘显微结构的动态变化,并分析总结其与胎盘物质交换及吸收等相关功能之间的关系,以期为改善胎盘功能性指标、提高母猪繁殖力提供理论依据。     

牦牛胎盘对小鼠组织中NO含量的影响

[目的]探讨牦牛胎盘对小鼠组织中NO含量影响,研究牦牛胎盘抗缺氧的机制。[手法]根据采集到胎盘的海拔高度将100只小鼠随机分为高海拔组、中海拔组、低海拔组和对照组,连续28天分别灌服不同海拔的牦牛胎盘和生理盐水,然后处死小白鼠快速采取肝、肺、心肌、骨骼肌、脾脏和肾脏,测定各组织内NO的含量。[结果]各海拔组肺,高、中海拔组心肌、骨骼肌中NO含量显著的高于对照组,差异极显著（p〈0．01）;高、中海拔组肝和肾脏,低海拔组心肌和骨骼肌NO的含量高于对照组,差异显著（p〈0．05）。【结论】牦牛胎盘提高小鼠肺、心肌、骨骼肌、肝和肾脏中NO的含量。     

一氧化氮对肉鸡肺动脉高压综合征的影响

肺动脉压升高是肉鸡肺动脉高压综合征(PHS)的重要发病机制。近年来研究表明一氧化氮(NO)在PHS发生发展中发挥着重要作用。本文论述了NO对肉鸡PHS发病过程的影响。一氧化氮合酶(NOS)和NO活性在PHS早期升高而后期下降。NO具有强大的扩张血管的作用,但在PHS过程中,NO合成相对不足,导致肺血管舒缩失衡,引起肺动脉压升高。肺血管重构是肉鸡肺动脉高压综合征的重要病理学变化特征,而NO可促进肺小动脉平滑肌细胞凋亡,在一定程度上抑制肺血管重构的形成。NO作为自由基对机体造成的损伤也是引起PHS的原因之一。在肉鸡日粮中补充NO前体物L-精氨酸可以增加内源性NO的生成,有助于降低PHS的发病率。     

Role of nitric oxide in hemodialysis-related hypotension in an experimental renal dysfunction dog model

To clarify the role of nitric oxide (NO) in hemodialysis (HD)-related hypotension, the relationship between plasma NO metabolites (NOx) and blood pressure changes, and the effect of N(G)-monomethyl-L-arginine (L-NMMA), a NO synthase inhibitor, on changes in blood pressure were evaluated in an experimental renal dysfunctional dog model. In order to create a renal dysfunction model, gentamicin was administered to male beagles in which 7 of 8 renal artery branches had been ligated. Normal renal functional and dysfunctional dogs underwent 3 hr of HD per day for 3 days. HD induced a transient decrease in mean blood pressure in the normal renal functional dogs. In renal dysfunctional dogs, a continuous hypotension occurred with a gradual increase in the plasma NOx concentration during HD. Although L-NMMA prevented the fall in blood pressure, it did not significantly change the plasma NOx concentration during HD. These results suggest that NO contributes to HD-related hypotension in renal dysfunctional dogs but the plasma NOx concentration does not reflect the change in blood pressure.     

精氨酸与高精氨酸的联系及其代谢产物一氧化氮对妊娠母猪繁殖性能的作用

一氧化氮（NO）既是妊娠期母体和胎儿体内平衡的关键调节因子，也是促进母体心血管变化、胎儿发育和生长以及适应宫内外生活的重要物质。精氨酸（Arg）与高精氨酸（h-Arg）是一对同源氨基酸，h-Arg是非必需的阳离子氨基酸，其可能由赖氨酸分解代谢或其前体Arg的氨基转移合成。它们均为NO的前体物质，对孕体具有相似的功能。在母猪妊娠期补饲Arg或h-Arg，能够增加孕体NO的含量。NO通过调控激素、血管的生成与增加养分供给等增加胚胎附植、减少胚胎死亡、增强胎儿发育，进而改善胎儿宫内发育受限（IUGR）与母猪繁殖性能。随着妊娠的进行，孕体氧化代谢增加，会产生大量的自由基。Arg或h-Arg代谢产生的NO通过上调Nrf2通路刺激谷胱甘肽（GSH）代谢相关基因的表达，增强孕体抗氧化能力，保证孕体与胎儿的健康发育。作者针对母猪妊娠期补充Arg或h-Arg，通过其代谢产物NO改善母猪IUGR、提高繁殖性能、增强机体抗氧化能力的作用与可能存在的机制进行综述，旨在为Arg与h-Arg在妊娠母猪上的应用提供理论支持。     

Effects of adrenergic agonists and antagonists on the blood pressure and heart rate of the pig fetus

The effects of adrenergic agonists and antagonists on blood pressure and heart rate were investigated in 18 chronically catheterised pig fetuses aged between 102 and 109 days of gestation (term is 114 days). One fetus had been decapitated in utero at 42 days of gestation. The alpha adrenergic agonist methoxamine produced a small but dose dependent hypertension and a dose related slowing in heart rate. The beta adrenergic agonist isoprenaline decreased mean arterial pressure in a dose related manner and produced tachycardia. Propranolol, a beta adrenergic blocker, increased mean arterial pressure and decreased heart rate. The response to subsequent alpha adrenergic blockade with phentolamine was hypotension and a slight bradycardia. Decapitation at 42 days of gestation did not seem to change the fetal responsiveness to adrenergic agonists but removed the blood pressure response to beta blockade. These observations indicate that the heart and circulation of the pig fetus are under adrenergic vasomotor control during late gestation.     

Influence of nitric oxide on the blood flow in the porcine uterine artery; an in vivo study

The aim of this study was to investigate the role of nitric oxide (NO) in the regulation of blood flow in the porcine uterine artery during the course of the oestrous cycle. Experiments were carried out on animals on days 1-5, 8-13 and 17-20 of the oestrous cycle. After induction of anesthesia and opening of the abdominal cavity, blood samples were collected from the ovarian and uterine arteries and veins to determine nitrate and nitrite concentrations; on the opposite side to the blood sampling the branch of the uterine artery was prepared and a venous catheter was inserted into the artery. For measuring the changes in the blood pressure the catheter was connected via a polyvinyl cannula to a pressure transducer. Sodium nitroprusside (NP; 2.4 microg, 24 microg and 240 microg; a NO donor) or Nomega-nitro-L-arginine methyl ester (L-NAME; 2.2 microg, 22 microg, 220 microg and 2200 microg; an irreversible inhibitor of neuronal and endothelial NO synthase and reversible inhibitor of macrophage NO synthase) was administered via a bolus into the uterine artery. Nitrite/nitrate concentrations were: higher (P < 0.05) in the uterine vein as compared to the uterine artery on days 1-5 of the oestrous cycle; lower (P < 0.05) in the uterine artery as compared to the ovarian and uterine veins as well as in the ovarian artery as compared to the ovarian vein on days 8-13 of the cycle; lower (P < 0.05) in the uterine artery as compared to the ovarian artery and uterine and ovarian veins on days 17-20. Administration of NP at doses of 2.4 microg and 24 microg and L-NAME at all doses examined did not affect (P > 0.05) the blood pressure in the uterine artery in all periods examined. NP at a dose of 240 microg decreased (P < 0.001) the blood pressure in the arteries in all periods examined as compared to blood pressure before NP treatment. The results obtained indicate that NO is involved in the regulation of blood flow through the porcine reproductive tract. Moreover, our results suggest that the action of NP in the porcine uterine artery is not dependent on the phase of the oestrous cycle.     

Effect of inhaled nitric oxide on experimentally induced pulmonary hypertension in neonatal foals

OBJECTIVE: To evaluate the efficacy of inhaled nitric oxide (NO) in anesthetized healthy newborn foals with experimentally induced pulmonary hypertension. ANIMALS: Five 1- to 3-day-old foals. PROCEDURE: Anesthesia was induced and maintained with propofol, and foals were intubated and mechanically ventilated. Systemic pressure and pulmonary arterial pressure (P(PA)) were recorded every 30 seconds. Hypertension was induced via a hypoxic gas mixture or chemical vasoconstriction, using the thromboxane mimetic U46619. Nitric oxide was added at a concentration of 80 parts per million (ppm) for 6 minutes under baseline conditions and during pulmonary hypertension-induced alveolar hypoxia (inspired oxygen concentration = 0.08). Nitric oxide (20, 40, 80, and 160 ppm) was evaluated during U46619-induced hypertension. Samples for determination of arterial blood gas tensions were collected before and after each NO treatment. RESULTS: Inhaled NO (approx 80 ppm) did not have an effect on baseline variables. Infusion of U46619 (0.35 +/- 0.04 microg/kg of body weight/min) or alveolar hypoxia resulted in increased P(PA) and decreased arterial oxygenation (PaO2) and hemoglobin saturation (HbSat). The increase in P(PA) was attenuated, in a dose-dependent manner, by NO during U46619 infusion and reversed by NO during induced hypoxemia. The PaO2 and HbSat were significantly improved at all NO doses during U44619 infusion but not during alveolar hypoxia. For all inhaled NO concentrations, nitrogen dioxide and methoglobin values were < 5 ppm and 3%, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Nitric oxide is a potent, selective vasodilator of the pulmonary circulation in healthy newborn foals. Inhaled NO may have value as a therapeutic agent in foals with pulmonary hypertension.     

Nitrate poisoning in cattle

Summary In a series of experiments the effect of administering KNO(2) was studied, during parturition, on the capability of oxygen transport of maternal blood and on oxygen transfer to foetal blood. The following blood parameters were analysed, MHb percentage, pO(2), O(2)-saturation, pH, pCO(2), and (NO(2)) in maternal arterial blood (carotid art.) and venous blood (jugular vein) and in foetal arterial blood (umbilical art.) and venous blood (umbilical vein). The relative O(2)-saturation was calculated from the estimated O(2)-saturation by multiplying with the factor Hb (mmol/1) minus MHb (mmol/1), divided by Hb (mmol/1). In addition, blood pressure in the carotid artery, heart rate, and respiration rate in the dam were continuously recorded for some hours. A dosage of 9 to 12 mg of NO(2)/kg body weight intravenously or of 30 mg of NO(2)/kg body weight orally to the dam caused much higher MHb percentages and NO(2) contents in the maternal blood than in the foetal blood. In maternal blood the ratio of NO(2) content td MHb percentage was proportional to that in foetal blood. In the arterial blood, MHb percentages were almost as high as in the venous blood. After administering of nitrite, relative O(2)-saturation dropped simultaneously with the increase in methaemoglobin. Nitrite treatment caused a drop in the maternal blood pressure; heart rate and respiration rate increased. O(2)-saturation in the blood in the umbilical vein was much lower in the animals with nitrite treatment than in those without. These experimental results show clearly that the oxygen capacity of the blood decreases after nitrite treatment. In pregnant cows the oxygen supply to the foetus will be adversely affected after nitrate intake, especially by the lower oxygen transfer via the placenta, though hardly at all by methaemoglobin formation in the foetal blood. When the oxygen transfer to the foetal blood decreases too sharply, intra-uterine death and ultimately abortion may result.     

妊娠早期饲粮中添加N-氨甲酰谷氨酸对母羊早期胚胎存活及相关血液指标的影响

本试验旨在研究妊娠早期饲粮中添加N-氨甲酰谷氨酸（NCG）对母羊胚胎存活及相关血液指标的影响,并对其作用机制进行初步探讨。选择发情正常、健康状况良好的湖羊50只,随机分为2组（对照组和NCG试验组）,每组25只母羊,自配种当天开始给母羊分别饲喂基础饲粮（对照组）和基础饲粮+0.11%NCG（NCG组）,饲喂期38 d。测定妊娠第19和38天母羊血浆游离氨基酸、总一氧化氮合酶（TNOS）、内皮型一氧化氮合酶（eNOS）、诱导型一氧化氮合酶（iNOS）、一氧化氮（NO）、雌二醇、孕酮的浓度;38 d时每组各屠宰7只妊娠母羊,测定妊娠母羊的黄体数和活胎儿数等指标。结果显示,与对照组相比,妊娠第38天时,NCG组每只母羊总胎儿数增加了79.72%（P<0.05）,活胎儿数增加了79.72%（P<0.05）,胎儿形成指数增加了0.26（P<0.05）,胎水体积增加了72.89%（P<0.05）,活胎儿总重提高了71.13% （P<0.05）;NCG组妊娠第19天的甘氨酸、蛋氨酸、赖氨酸、精氨酸、NO、iNOS、eNOS和孕酮的浓度显著高于对照组（P<0.05）,NCG组妊娠第19天的瓜氨酸和脯氨酸极显著高于对照组（P<0.01）;NCG组妊娠第38天的精氨酸、脯氨酸和NO显著高于对照组（P<0.05）,NCG组妊娠第38天的iNOS和eNOS的浓度极显著高于对照组（P<0.01）。由此,妊娠早期饲粮中添加NCG提高了胚胎和胎儿的存活,增加了妊娠母羊第38天的总胎儿数和活胎儿数,改善了母羊的繁殖性能,其作用机制可能是NCG促进了母羊内源性精氨酸的合成,提高了母羊血浆精氨酸、NO和孕酮含量,改善了子宫内环境和营养供给,使之有利于胚胎着床和妊娠维持。     

一氧化氮的生物学活性及其在肝脏损伤中的作用

一氧化氮（Ｎｉｔｒｉｃ ｏｘｉｄｅ,ＮＯ）是一种难溶于水的脂溶性气体。它在体内扮演着生理和病理的双重角色。小剂量ＮＯ有着重要的信息传递作用。在神经系统中具有类似神经递质的信息传递功能,在免疫系统中具有杀灭肿瘤细胞、细菌、寄考虫和病毒的作用;在心血管系统中具有扩张血管,抑制血小板聚集与粘附,调节血流和血压的功能,但大剂量ＮＯ,又可产生细胞毒笥,导致组织细胞损伤,是肝组织损伤的重要介导因子。     

饲粮中添加不同水平L-精氨酸对妊娠母猪繁殖性能及血液生化指标的影响

本研究探讨饲粮中添加不同水平L-精氨酸(L-Arg)对母猪繁殖性能及血浆一氧化氮相关指标的影响。试验选择36头2胎次母猪(长白×大约克),随机分为4组,每组9头母猪。各组饲粮分别在基础饲粮中添加0 L-Arg+1.70%L-丙氨酸(L-Ala)(0 L-Arg组)、0.4%L-Arg+1.02%L-Ala(0.4%L-Arg组)、0.7%L-Arg+0.51%L-Ala(0.7%L-Arg组)和1.0%L-Arg+0 L-Ala(1.0%L-Arg组),各组添加L-Ala以满足等氮平衡需要。试验期从母猪配种当天到分娩。结果表明:1.0%L-Arg组比0 L-Arg组显著提高了窝产活仔数和初生窝重(P<0.05),随着饲粮中L-Arg水平的提高,窝产仔总数和初生个体重有上升趋势(P>0.05);母猪妊娠第30、60和90天,1.0%L-Arg组血浆中Arg、鸟氨酸含量均显著或极显著高于0.7%、0.4%、0 L-Arg组(P<0.05或P<0.01);母猪妊娠第90天,各组间的血浆脯氨酸含量均有极显著差异(P<0.01),但第30、60天差异均不显著(P>0.05);母猪妊娠第30、60、90天,1.0%L-Arg组血浆一氧化氮含量和第90天血浆总一氧化氮合酶(TNOS)、诱导型一氧化氮合酶(iNOS)活性均显著或极显著高于0.7%、0.4%、0 L-Arg组(P<0.05或P<0.01)。经回归分析,母猪的窝产仔总数、窝产活仔数、初生窝重、血浆中各氨基酸、一氧化氮含量及TNOS和iNOS的活性与饲粮L-Arg水平均有显著或极显著的线性关系(P<0.05或P<0.01)。结果提示,饲粮中L-Arg水平变化对母猪妊娠后期血液生化指标影响明显,饲粮中添加1.0%L-Arg对提高母猪繁殖性能效果最佳。