妊娠后期营养限饲对蒙古绵羊胎儿肝脏生长发育及抗氧化能力的影响

本试验旨在研究妊娠后期营养限饲对蒙古绵羊胎儿肝脏生长发育及抗氧化能力的影响。选择健康的蒙古绵羊42只(经同期发情受孕),在妊娠90d时选择6只母羊进行屠宰,其余按体重随机分配到3个组:限制组1(0.175MJ ME·kgw-0.75·d-1,n=14,RG1)、限制组2(0.33MJ ME·kgw-0.75·d-1,n=12,RG2)和自由采食组(0.67MJ ME·kgw-0.75·d-1,n=10,CG),进行不同能量水平饲养。饲喂至妊娠140d,各组再选择6只母羊进行屠宰。结果表明,RG1组胎儿重(P<0.01)、胎儿肝脏重(P<0.01)、肝脏中DNA浓度(P<0.01)、蛋白浓度(P<0.01)、总DNA含量(P<0.01)、蛋白质/DNA(P<0.01)、总抗氧化能力(P<0.01)、超氧化物歧化酶活性(P<0.05)显著低于CG组,而谷胱甘肽过氧化物酶活性(P<0.05)和丙二醛浓度(P<0.01)显著高于CG组;RG2组胎儿重(P<0.01)、肝脏重(P<0.05)、肝脏中DNA浓度(P<0.01)、蛋白浓度(P<0.01)、总DNA含量(P<0.01)、蛋白质/DNA(P<0.01)、总抗氧化能力(P<0.01)显著低于CG组,而丙二醛浓度(P<0.01)显著高于CG组。结果显示,妊娠后期营养限饲蒙古绵羊严重影响了其胎儿肝脏的生长发育和抗氧化能力,而且随着营养水平的降低,发育受阻程度加深,抗氧化防御敏感性增强。     

妊娠后期营养限饲蒙古绵羊对其胎儿生长发育及血液生理生化指标的影响

本试验旨在研究妊娠后期营养限饲蒙古绵羊对其胎儿生长发育及血液生理生化指标的影响。选择健康的蒙古绵羊(经同期发情受孕)42只,在妊娠90 d时选择6只母羊进行屠宰,其余分为3个代谢能水平组:0.175 MJ/(kg BW0.75.d)组(RG1:n=14)、0.330 MJ/(kg BW0.75.d)组(RG2:n=12)和自由采食组[CG:0.670 MJ/(kg BW0.75.d),n=10],继续饲喂。妊娠140 d时,每组再选择6只母羊进行屠宰,快速取出胎儿,测定胎儿体重、体尺及血液生理生化指标。结果表明:RG1胎儿体重(P<0.01)、体长(P<0.05)、胸围(P<0.05)、腹围(P<0.05)、曲冠臀长(P<0.01)、红细胞数(P<0.01)、血红蛋白含量(P<0.01)、红细胞压积(P<0.01)、总氨基酸含量(P<0.05)、总抗氧化能力(P<0.01)、超氧化物歧化酶活性(P<0.05)显著低于CG,而红细胞分布宽度变异系数(P<0.05)、平均血小板体积(P<0.05)、非酯化脂肪酸含量(P<0.05)、β-羟基丁酸含量(P<0.01)、谷胱甘肽过氧化物酶活性(P<0.05)、丙二醛含量(P<0.05)显著高于CG;RG2胎儿体重(P<0.01)、总抗氧化能力(P<0.05)显著低于CG,而平均血小板体积显著高于CG(P<0.05)。结果提示,妊娠后期营养限饲蒙古绵羊严重限制了其胎儿的生长发育,RG1胎儿产生营养性贫血,营养代谢失调,发生氧化应激。     

妊娠后期营养限饲对蒙古绵羊体贮动员及其胎儿生长发育的影响

本试验旨在研究妊娠后期营养限饲对蒙古绵羊体贮动员及其胎儿生长发育的影响。选择健康的蒙古绵羊35只(经同期发情受孕),在妊娠90 d时选择6只母羊进行屠宰,其余按体重随机分为3组,分别为自由采食组[C组,代谢能(ME)日均采食量为0.670 MJ/(kg W0.75.d),n=8]、限饲1组[R1组,ME日均采食量为0.175 MJ/(kg W0.75.d),n=12]、限饲2组[R2组,ME日均采食量为0.330 MJ/(kg W0.75.d),n=9],试验至妊娠140 d结束,每组再选择6只母羊进行屠宰。结果表明:妊娠140 d,R1组母体净失重,胴体重,肉中干物质、粗脂肪、粗蛋白质、粗灰分含量,血浆葡萄糖(GLU)、总氨基酸(TAA)浓度极显著低于C组(P<0.01),而非酯化脂肪酸(NEFA)、β-羟丁酸(BHBA)浓度极显著高于C组(P<0.01);R2组母羊净失重,胴体重,肉中干物质、粗脂肪含量及血浆GLU、TAA浓度极显著低于C组(P<0.01),而血浆NEFA浓度极显著增加(P<0.01)。母羊失重导致R1组和R2组胎儿重均极显著低于C组(P<0.01),而且R1组体长(P<0.05)、胸围(P<0.05)、腹围(P<0.05)和曲冠臀长(P<0.01)显著或极显著低于C组。总之,妊娠后期随着营养水平的降低,限饲ME日均采食量为0.330 MJ/(kg W0.75.d)时,母体的缓冲保护系统仍对胎儿有一定的作用,而继续限饲至ME日均采食量为0.175 MJ/(kg W0.75.d)时,母体的营养缓冲系统可能已被打破,严重影响到其胎儿的生长发育。     

妊娠后期营养限饲对蒙古绵羊胎儿肝脏脂类代谢的影响

本试验旨在研究妊娠后期宫内生长受限(IUGR)对蒙古绵羊胎儿肝脏脂类代谢能力的影响。选择体重相近、2~3胎次、经同期发情且同期受孕、健康的蒙古绵羊24只,在妊娠90d时选择6只母羊进行屠宰,其余按体重随机分配到3个组:0.175 MJ/(kg BW0.75·d)组(RG1组)、0.330 MJ/(kg BW0.75·d)组(RG2组)和0.670 MJ/(kg BW0.75·d)组[自由采食组(CG组)],每组6只。饲喂至妊娠140d,屠宰取胎儿肝脏和血浆用于分析。结果表明:妊娠140d,RG1组胎儿肝脏重(P0.01),肝脏干物质(P0.01)、粗脂肪(P0.05)、粗蛋白质(P0.01)、粗灰分(P0.05)、水分的质量(P0.01),甘油三酯(P0.01)、总胆固醇含量(P0.01),脂蛋白酯酶(P0.01)、肝酯酶活性(P0.05)以及血浆中甘油三酯含量(P0.05)显著或极显著低于CG组,而血浆中β-羟基丁酸(P0.01)、非酯化脂肪酸(P0.05)、总胆固醇含量(P0.05)显著或极显著高于CG组;RG2组肝脏重(P0.05)、水分质量(P0.01)、脂蛋白酯酶活性(P0.01),血浆中甘油三酯含量(P0.05)显著或极显著低于CG组。妊娠后期IUGR限制了绵羊胎儿肝脏的生长发育,脂肪合成能力受到严重影响,肝脏中脂蛋白酯酶和肝酯酶活性降低,血浆中脂类代谢产物含量升高。     

妊娠后期限饲对母羊肝脏功能及抗氧化的影响

本研究旨在评估母羊妊娠后期限饲对其肝脏功能及抗氧化性能的影响。试验选择平均体重为(52.82±2.72)kg的妊娠后期母羊(2~3胎次)36只,随机分为3组,每组6个重复,每个重复2头羊。各组分别饲喂对照组日粮(代谢能:0.68 MJ/kg代谢体重/d)、处理1组日粮(代谢能:0.17 MJ/kg代谢体重/d)、处理2组日粮(代谢能:0.34 MJ/kg代谢体重/d),试验从妊娠90 d持续至140 d。结果:处理1组母羊肝脏脂肪含量较对照组和处理2组显著提高了288.03%和282.48%(P<0.05)。与对照组相比,处理1组肝脏水分、灰分和蛋白质占比显著降低19.28%、44.32%和45.83%(P<0.05),但处理1组肝脏脂肪占比较对照组显著提高210.19%(P<0.05)。处理1组和处理2组血清非酯化脂肪酸含量较对照组分别提高199.94%和185.51%(P<0.05)。与对照组相比,处理1组血清β-羟丁酸和肝脏甘油三酯含量显著提高392.45%和329.55%(P<0.05)。处理1组肝脏超氧化物歧化酶、过氧化氢酶和总抗氧化力活性较对照组显著提高103.32%、83.36%和75.85%(P<0.05),同时处理1组丙二醛含量较对照组和处理2组显著提高54.52%和67.31%(P<0.05)。结论:妊娠后期限制母羊采食量会导致肝脏重量和蛋白质含量下降,同时引起肝脏脂肪的积累,肝脏抗氧化功能失衡。     

妊娠后期胎儿宫内生长受限对蒙古绵羊胎儿胸腺生长发育的影响

本试验旨在研究妊娠后期胎儿宫内生长受限(Intrauterine growth retardation,IUGR)对蒙古绵羊胎儿胸腺及其T淋巴细胞发育的影响.选择健康的蒙古绵羊42只(经同期发情受孕),在妊娠90d时选择6只母羊进行屠宰,其余按体质量随机分配到3个组:限制组1(RG1,0.175 MJ·kgW-0.75·d-1(n=14))、限制组2(RG2,0.33MJ·kgW-0.75·d1(n=12))和自由采食组(CG,0.67 MJ·kgW 0.75·d-1,(n=10)),进行不同能量水平饲养.至妊娠140 d,各组再选择6只母羊进行屠宰.结果表明,妊娠后期限饲母羊严重限制了限饲组胎儿体质量(P＜0.01),导致RG2(P＜0.05)、RG1组(P＜0.01)胎儿胸腺质量、胸腺皮质厚度、胸腺总DNA含量以及RG1组胎儿胸腺的皮质/髓质比值、总蛋白质含量显著低于CG组(P＜0.01);RG1组胎儿胸腺的SOD酶活性(P＜0.05)、T-AOC浓度(P＜0.01)显著低于CG组,GSH-PX酶活性(P＜0.05)、MDA浓度(P＜0.05)显著高于CG组 ;RG2、RG1组胎儿的胸腺中CD4+ CD8+双阳性T淋巴细胞均显著低于CG组(P＜0.05).结果显示,妊娠后期IUGR严重影响了胎儿胸腺及其T淋巴细胞的生长发育,这必将影响IUGR胎儿细胞免疫能力及出生后的健康.     

妊娠后期IUGR对蒙古绵羊胎儿肝脏糖代谢的影响

为了研究妊娠后期宫内生长受限对蒙古绵羊胎儿肝脏糖代谢能力的影响,试验采用健康的蒙古绵羊24只,经同期发情和同期受孕,选择6只在妊娠90天时进行屠宰。其余随机分为3组,限制1[0.18 MJ/(BW0.75·d),RG1]组、限制2[0.33 MJ/(BW0.75·d),RG2]组和自由采食[0.67 MJ/(BW0.75·d),CG]组,按各组能量水平进行饲养;至妊娠140天时屠宰,测定胎儿肝脏重、肝脏生长速率及肝脏、血液中的肝糖原、血糖、丙酮酸、乳酸等含量。结果表明:RG1组胎儿肝脏重(P0.01)、肝脏生长速率(P0.01)及肝脏中肝糖原含量(P0.01)、丙酮酸含量(P0.05)、乳酸含量(P0.01)均低于CG组,而血液中丙酮酸含量(P0.01)、乳酸含量(P0.01)均高于CG组;RG2组胎儿肝脏重(P0.05)、肝脏生长速率(P0.05)、肝糖原含量(P0.01)低于CG组,而血液中乳酸含量高于CG组(P0.05)。说明妊娠后期宫内生长限制抑制了绵羊胎儿肝脏的生长发育,胎儿肝脏重和生长速率受到严重影响,肝糖原含量降低,糖异生能力增强,血液中乳酸和丙酮酸含量升高,胎儿肝脏糖代谢受到严重影响。     

限饲对肉鸡生产性能的影响

从20世纪20年代肉用仔鸡兴起至今已经过了80多年，这期间科研工作者和生产者无论从肉鸡的选育角度和饲养角度，都是单纯追求提高肉鸡的增重速度，这样虽然使肉用仔鸡的出场日龄大大提前，但是也使肉鸡出现了腹脂和体脂沉积过多等问题。动物机体中的脂肪虽然是维持生命、生长和生产都不可缺少的物质，然而，随着生活水平的提高，人们对低胆固醇     

妊娠后期营养限制对蒙古绵羊胎儿生物原胺类神经递质的影响

本试验旨在研究妊娠后期营养限制对蒙古绵羊胎儿生物原胺类神经递质的影响。选择健康、体况相近的蒙古绵羊18只,对其进行同期发情、配种后,从妊娠第90天开始,随机分为3个组:营养限制1组[NG1组,n=6,代谢能(ME)=0.175 MJ/(kg BW 0.75·d)]、营养限制2组[NG2组,n=6,ME=0.330 MJ/(kg BW 0.75·d)]和对照组[CG组,n=6,ME=0.670 MJ/(kg BW 0.75·d)],在妊娠第140天时屠宰,取各组胎儿及其脑组织和血液。结果显示:NG1组胎儿的脑重较CG组显著增高(P<0.05),并且NG1组胎儿脑中5-羟色胺(5-HT)(P<0.01)、肾上腺素(EPI)(P<0.05)含量显著或极显著高于CG组,去甲肾上腺素(NA)的含量极显著低于CG组(P<0.01)。NG2组胎儿脑中5-HT含量极显著高于CG组(P<0.01),而NA(P<0.01)、多巴胺(DA)(P<0.05)含量显著或极显著低于CG组。另外,NG1组胎儿血浆中5-HT(P<0.01)、EPI(P<0.01)、NA(P<0.05)、DA(P<0.01)含量显著或极显著低于CG组;NG2组胎儿血浆中5-HT(P<0.01)、NA(P<0.01)、DA(P<0.05)含量显著或极显著低于CG组。由此得出,妊娠后期营养限制使得蒙古绵羊胎儿脑中5-HT、EPI含量升高和NA含量降低,血浆中5-HT、EPI、NA、DA含量降低。     

甜菜碱对生长期限饲猪营养利用和营养分配的影响

试验的目的是测定不同浓度的甜菜碱（0－0.5%）对生长期限饲猪生长和体组成的影响。甜菜碱可减少液体沉积，改变宰前肥育猪的蛋白质利用率。而且，甜菜碱对于能量限饲猪的生长和胴体组成有更大影响，取32头去热公猪（36kg,n=8／组）用玉米－豆粕脱脂奶型基础日粮（Cp=18.6%,ME=3.23Mcal/kg）进行限饲试验。喂量为粮量的1／4，分别补加0％、0.125%、0.25%、0.5%甜菜碱，每周根据体重调整粮的分配，以保证所有组平均进食量约为1.7kg。达64kg时，将猪宰杀并取内脏称重，胴体冷藏24h以便进行胴体测定。随后，1／2胴体和全部内脏进行化学成分分析。线性回归分析表明，日粮中甜菜碱含量从0％提高到0.5%，胴体脂肪沉积（P＝0.06）、P3脂肪高度（P＝0.14）、和内脏重（P＝0.129）均下降，而胴体总蛋白（P＝0.98）、蛋白沉积率（P＝0.98）、瘦肉率（P＝0.115）均提高。试验观察到，差异较大的组为添加0.5%甜菜碱的组，胴体脂肪沉积和P3脂肪高度分别下降10％和26％。其它脂肪高度测量值差异不显著（P＞0.15）。另外，添加碱较高的组与对照组相比，胴体蛋白与脂肪的比值提高19％，蛋白沉积率提高23％，瘦肉率提高24％，日粮添加甜菜碱对于生长性能（P＞0.15），内脏化学组成、胴体脂肪沉积、内脏脂肪和蛋白沉积率、血清脲和氨气浓度没有影响。这些数据表明，甜菜碱改变营养分配，导致胴体蛋白沉积提高，而胴体脂肪和内脏组织沉积减少。     

Effects of intrauterine growth restriction during late pregnancy on the ovine fetal renal function and antioxidant capacity

This study investigated the effects of intrauterine growth restriction during late pregnancy on the ovine fetal renal function and renal antioxidant capacity. Eighteen ewes pregnant were randomly divided into control group (CG, ad libitum, 0.67 MJ ME·BW^−0.75·day⁻¹, n = 6), restricted group 1 (RG1, 0.18 MJ ME·BW^−0.75·day⁻¹, n = 6), and restricted group 2 (RG2, 0.33 MJ ME·BW^−0.75·day⁻¹, n = 6). At 140 days, the fetal blood, allantoic fluid and kidney tissue were collected to determinate fetal renal function and renal antioxidant capacity. The results showed that the fetal weight, kidney weight, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), aquaporin-2 (AQP-2) and aquaporin-3 (AQP-3), and total antioxidant capacity (T-AOC) in RG1 group were decreased compared with the CG (P < 0.05), but the contents of β2-Microglobulin (β 2-MG), cystatin C (Cys-C), filtered sodium excretion fraction (FENa), malondialdehyde (MDA), and hydroxyl radical (OH) in RG1 group were increased (P < 0.05). The impaired ovine fetal renal growth, antioxidant imbalance and dysfunction of glomerulus ultrafiltration, and the renal tubules reabsorption were induced by maternal malnutrition during late pregnancy.     

Dietary N-carbamylglutamate or L-arginine improves fetal intestinal amino acid profiles during intrauterine growth restriction in undernourished ewes

Our previous studies demonstrated that prenatal in utero growth restriction impairs postnatal intestinal function.Thus,improving postpartal intestinal absorption capacity and growth by manipulating the maternal diet prepartum is of importance.This work was conducted to determine whether supplementation of N-carbamylglutamate(NCG)or rumen-protected L-arginine(RP-Arg)increased fetal intestinal amino acid(AA)profiles in intrauterine growth retardation(IUGR)fetuses.On d 35 of gestation,Hu ewes(n=32)carrying twin fetuses were randomized into 4 groups(8 ewes and 16 fetuses in each group),where diets were as follows:100%of nutrient requirements recommended by National Research Council(NRC,2007)(CON);50%of nutrient requirements recommended by NRC(2007)(RES);RES+RPArg(20 g/d),(RES+ARG);and RES+NCG(5 g/d),(RES+NCG).On d 110 of gestation,both fetal and maternal tissues were collected and weighed.Compared with RES,solute carrier family 1,member 5(SLC1A5)was upregulated(P<0.05)within fetal jejunum,duodenum and ileum when supplementing NCG and RP-Arg.Relative to RES,RP-Arg or NCG supplementation to RES resulted in upregulation(P<0.05)of peptide transporter 1 protein abundance within the fetal ileum.NCG or RP-Arg supplementation to RES also upregulated phosphorylated mechanistic target of rapamycin(pmTOR)-to-mTOR ratio in the fetal ileum induced by IUGR(P<0.05).As a result,during IUGR,supplementation of Arg or NCG affected intestinal AA profiles in the fetus in part through controlling mTOR signal transduction as well as AA and peptide transport.Future studies should be conducted to understand the role(if any)of the placenta on the improvement of growth and AA profiles independent of the fetal intestine.This would help demonstrate the relative contribution of intestinal uptake in fetal life.     

不同营养水平限制饲养对妊娠期蒙古绵羊生长激素受体(GHR)mRNA表达水平的影响

为了阐明不同营养水平限制饲养妊娠期母羊后,在不同生长阶段对蒙古绵羊生长激素受体(GHR)mRNA表达水平的影响,研究根据GenBank中绵羊的GHR序列,设计1对预计扩增产物为395 bp的引物,采用RT-PCR技术检测了蒙古绵羊在不同营养水平条件下肝脏和背最长肌中GHR mRNA表达量的变化。结果表明:在限制采食阶段,低营养水平组即营养限制组(RG1组)和阈值组(RG2组)肝脏的GHR mRNA表达水平低于正常营养的对照组(CG组),而背最长肌的GHR mRNA表达水平高于对照组,说明限制营养对绵羊GHR水平的影响具有组织特异性。在补偿生长结束阶段,RG1组和RG2组绵羊的肝脏和背最长肌中GHR mRNA表达水平均恢复到对照组水平。     

Effect of pregnancy and fetal development on sheep liver superoxide dismutase activity

Liver cytosolic CuZn SOD activity of four-week and 12-week pregnant sheep was twice as high as that of their fetuses and almost equal to that of control, barren ewes. By the 20th week of pregnancy activity had decreased by about 70 per cent in the maternal liver and increased to a value similar to that of the controls in the fetuses. The lysosomal CuZn SOD activity remained almost unchanged during pregnancy both in the maternal and fetal livers. Cytosolic and lysosomal CuZn SOD activities of 20-week pregnant sheep and their fetuses showed a similar electrophoretic pattern and low electrophoretic mobility. Hepatic Mn SOD activity increased sharply during fetal development but remained lower than that in both the control and maternal livers. It is proposed that the changes in CuZn SOD and Mn SOD activities are associated with changes in copper metabolism and oxygen utilisation, respectively. The low electrophoretic mobility of CuZn SOD is assumed to be a species specificity.     

Serum lipid profile in Iranian fat-tailed sheep in late pregnancy, at parturition and during the post-parturition period

Blood samples were obtained from 12 Iranian fat-tailed sheep during 7 weeks pre-partum, at parturition and 7 weeks post-partum. The lipids measured were cholesterol, triglyceride, total lipid, high-density lipoprotein (HDL)-cholesterol, low-density lipoprotein (LDL)-cholesterol, and very low-density lipoprotein (VLDL)-cholesterol. The concentrations of cholesterol, triglyceride, HDL-cholesterol and VLDL-cholesterol during the 7 weeks pre-partum, at parturition and the 7 weeks post-partum were significantly different (P < 0.05). One week before parturition, the concentrations of cholesterol, triglyceride, HDL-cholesterol and VLDL-cholesterol were higher (P < 0.05) than at other periods. The lowest concentrations of these parameters were observed 2-3 weeks after parturition. In this study, significant positive correlations were observed between the time of sampling (pre-partum, parturition and post-partum) and serum cholesterol (r = 0.22; P < 0.01) and HDL-cholesterol (r = 0.25; P < 0.01).     

Effects of fluprostenol administration in mares during late pregnancy

The effectiveness of the prostaglandin F analogue fluprostenol in inducing labour in the mare was examined by giving sequential injections over the last 50 days of gestation. The behavioural and endocrine changes elicited by the drug in pregnant and non-pregnant animals and in foals were also studied. Fluprostenol (250 or 500 micrograms intramuscularly) failed to induce labour before 320 days gestation; thereafter its effect was capricious. Twelve mares foaled 1 to 36 h after the last test; eight delivered normal, viable, apparently 'term' foals and four produced stillborn/premature animals. Eight of the deliveries (five term and three pre-term foals) could be ascribed to the action of fluprostenol because they occurred 1 to 6 h after its administration, at a time when spontaneous foaling would have been unlikely. The other four mares foaled between 12 and 36 h after the fluprostenol injection and it is therefore doubtful whether there was a causal relationship between the two events. In the mares which delivered viable foals the pre-partum milk samples were characteristic of full term samples with respect to calcium, sodium and potassium. Those which delivered premature/stillborn foals had low calcium and a high sodium/potassium ratio in the pre-partum milk. Behavioural changes (sweating, increased respiration, defaecation etc), which varied in intensity between tests and individuals, were seen in all three groups of animals following the administration of fluprostenol. These changes were accompanied by rises in plasma cortisol and adrenocorticotrophic hormone concentration during the 2 h sampling period, suggesting a centrally mediated response to the drug.(ABSTRACT TRUNCATED AT 250 WORDS)     

苏尼特羊妊娠后期限制饲养对其羔羊初生重的影响

基于妊娠后期胎儿生长最快的特点 ,研究在妊娠 90d将 4 5只平均体重为 4 1 4 5kg±3 81kg、体况中等、胎次为 2～ 3的苏尼特经产妊娠母羊随机分为四个营养水平组 (每天每千克代谢体重 0 2 0、0 33、0 4 4、0 86MJ) ,目的在于研究在妊娠后期 (90～ 15 0d)不同限制程度饲养能量水平对羔羊初生重的影响。结果表明不同饲养能量水平导致四组羔羊平均初生重分别为 2 80 1、3 375、3 6 98、3 6 6 6kg ,其中后三组羔羊初生重间无显著差异 (P >0 0 5 ) ,而 0 2 0MJ组显著 (P <0 0 5 )降低其初生重。在限制饲养期间 ,不同组别母羊净失重不同 ,依次为 11 13、7 2 3、4 4 2、0 93kg ,分别占妊娠 90d各组母羊净重的 2 7 9%、17 9%、11 3%、2 4 %。可见在妊娠后期母体失重达到试验开始时母体净重的17 9% ,仍不影响羔羊初生重 ,达到 2 7 9%时仍能完成妊娠。这表明苏尼特羊对低能量是有很强的适应性的     

发育中后期羊胎儿肺脏显微与超微结构的研究

现今对哺乳动物胚胎发育方面的研究主要侧重于对胚胎早期发育，以及早期胚胎发育的调控因素的研究。而对胚胎着床以后，特别是妊娠中后期胎儿发育的研究报道较少。国内外对胎儿发育中后期肺脏超微结构的研究报道更少，仅检索到一篇关于胎羊围产期肺脏的报道，到目前为止还未发现有对绵羊胎儿肺脏发育过程中组织超微结构的研究报道。本文旨在揭示小尾寒羊妊娠中后期胎羊肺脏组织的发育规律，为早产胎儿的护理提供理论知识，并为研究其他动物胎儿肺脏成熟提供借鉴。