共查询到19条相似文献，搜索用时 203 毫秒
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当母畜发情受孕一定时间后,子宫内膜就会发育形成组织结构复杂的胎盘（俗称胎衣）。胎盘是维持胎儿生长发育的重要器官,具有物质交换和内分泌两种机能。胎儿生长发育所需营养物质、水分、氧气和一些激素等都是通过胎盘和母体的血液循环获得的,同时胎儿生长发育过程中新陈代谢所产生的代谢产物也通过胎盘与母体的血液循环而排出体外。 相似文献
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妊娠是母畜在生殖过程中一个特殊而又重要的阶段,妊娠后母体出现各种生理性的负荷,在妊娠期,从日粮中获得的营养物质除了维持自身机体代谢和消耗外,胎儿生长发育所需要的营养物质也是直接由母体供给,尤其在妊娠后期,胎儿发育迅速,需要的营养物质更多,妊娠后期的生长发育对其出生后的生长发育与生产性能有着极为重要的意义,它受到来自母体和胎儿本身许多因素的影响和调节,如果母体孕期营养不良,会造成胎儿宫内发育受阻,影响胎儿出生时的营养状况;到了哺乳期,后代生长发育所需要的营养物质与微量元素也主要由母体的乳汁提供,母乳中的营养物质与微量元素的水平直接影响后代组织器官的功能及机体的生长发育,研究认为母体的营养状况可通过代谢印痕影响后代体重.乳汁组成可能是代谢印痕的一个决定因素. 相似文献
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有机体的生长发育与一定外界环境条件有密切关系。在良好的饲养条件下与不良饲养条件下,羔羊所进行的生长发育是不同的。由于营养不良在羔羊发育过程中所引起的缺乏,不仅影响它的大小和生长速度,同时也影响到它的内部器官和组织的发育。 相似文献
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正动物胎儿的生长发育受到各种环境和其他因素的影响,这些因素包括母体营养水平、母体肠吸收情况、羊膜液和尿囊液营养物提供情况、是否摄入有毒物质、环境温度和应激、干扰母体或胎儿的代谢和体内平衡机制、子宫状况、子宫内膜或胎盘的功能以及养殖管理等[1]。虽然胎儿的基因组对胎儿在子宫内的生长潜力具有重要作用,但越来越多的证据表明子宫内环境和胎盘环境是决定胎儿生长的主要因素。子宫容量不足和胎盘机能不全是阻碍胎儿生长和导致宫内生长迟缓(IUGR)的两个重 相似文献
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刚出生的犊牛，因各种组织器官均未充分发育，皮肤保护机能、免疫、神经、内分泌等系统的结构和机能尚未发育完全，对外界不良环境防御、适应能力低下，在出生后两个月内容易被病菌侵袭或发生机能障碍；若在胎内发育阶段母体营养缺乏，则会造成犊牛先天性营养不良性疾患。这些疾患轻则妨碍生长发育，重则导致死亡。 相似文献
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能量对妊娠后期母羊健康及其羔羊的影响 总被引：1，自引：0，他引：1
妊娠后期是胎儿生长发育的关键时期,胎儿体重增长的80%在此阶段完成,因此该阶段母羊的能量需要量大于其他生理阶段。高产多胎是肉用种母羊的重要培育目标,当母羊处于营养水平较低的草场或舍饲条件下,怀双羔或多羔母羊的日粮能量水平不能满足其营养需要时,母羊会动用体内的糖原、体蛋白和体脂以弥补能量不足,致使母羊的代谢紊乱,肝机能受损,产生羊妊娠毒血症,影响母羊的健康和胚胎的健康生长,产出弱羔、病羔,并可能影响产后羔羊的健康生长。因此,研究妊娠后期能量水平对母羊健康、胚胎发育、羔羊生长及肉羊养殖业的发展都有重要的指导意义。作者对不同能量水平对妊娠母羊的健康、繁殖性能、泌乳性能、胚胎与羔羊生长的影响展开讨论,阐明妊娠后期能量的作用。当母羊妊娠后期能量受到限制时,母羊的体重降低,乳腺发育受阻,泌乳能力下降,受胎率下降;同时胚胎的生长速度降低,影响胚胎与产后羔羊组织器官发育和正常生长。 相似文献
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We hypothesized that the ability of the fetus to alter nutrient shunting and organ growth might be associated with uterine capacity. White crossbred gilts from a randomly selected control line, a line selected for ovulation rate, and a line selected for uterine capacity (UC) were unilaterally hysterectomized-ovariectomized at 160 d of age, mated at estrus, and slaughtered at 45, 65, 85, and 105 d of gestation (9 to 18 gilts for each line x day combination). Analysis of the data revealed that heart weights and fetal weights were decreased in the ovulation rate line. No significant differences were obtained in fetal, placental, or fetal organ weights between the control and UC lines. Allometric growth of organs was assessed by examination of the slopes of the relationships between fetal weights and fetal organ weights after natural log transformation. Only the relative growth of the liver differed between selection lines and was greater (P = 0.01) in the UC compared with the control line during early pregnancy (d 45 and 65). Allometric growth of the fetal brain, liver, and heart differed with day of gestation. A brain-sparing effect was greater (P < 0.01) on d 85 and 105 compared with d 45 and 65. By contrast, a heart-sparing effect was present during early gestation and disappeared in later gestation. Fetal liver weights were hypersensitive to differences in fetal weights on d 45, possibly associated with placental effects on fetal liver weight. Fetal spleen weights were proportional to fetal weights throughout gestation. These results indicate that selection for ovulation rate decreased total fetal and fetal heart weights, and that selection for UC altered the relationship between total fetal and fetal liver weights during early gestation. Results further indicate significant changes in allometric growth of organs during gestation. 相似文献
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Remarkable diversity of size and health of offspring exists after normal pregnancies. When pregnancies are complicated by an extrinsic variable such as inappropriate maternal nutrition, birth weight and health of the neonate are substantially affected. The placenta is the organ through which respiratory gases, nutrients, and wastes are exchanged between the maternal and fetal systems. Thus, transplacental exchange provides for all the metabolic demands of fetal growth. Transplacental exchange is dependent upon uterine and umbilical blood flow, and blood flow rates are in turn dependent in large part upon vascularization of the placenta. Therefore, factors that influence placental vascular development will have a dramatic impact on fetal growth and development, and thereby on neonatal mortality and morbidity. Recent work from our laboratories has focused on the effects of nutrient intake during pregnancy on placental growth and vascular development. Both nutrient restriction of the adult dam and overnourishment of the adolescent dam during pregnancy suppress placental cell proliferation and vascularity. Furthermore, placental expression of angiogenic factors and their receptors, factors that are known to affect vascular growth, are perturbed by level of nutrition. Studies in this area will lead to improved methods to manage nutritionally-compromised pregnancies. 相似文献
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The late pregnancy is a critical period of fetal growth and development. As approximately 80% of fetal body weight is obtained during late gestation, so that the amount of energy needed for the ewes at this period is much greater than the other periods. Now ewes with multiple fetuses are mutton sheep breeding cultivation objectives, however,under the grazing or confined feeding conditions where nutrient requirement can't satisfy the nutrient requirement of sheep, especially for pregnant ewes with twins or more lambs.The body glycogen and protein as well as body fat will be mobilized for energy needed for the fetal growth and reproduction, which would lead to bad influence on ewes (metabolic disorders, liver function damage, pregnancy toxemia, embryonic development and health) and also on lamb (weak lamb, dead lamb and health). Therefore, investigating the effects of dietary energy levels during late gestation on the ewe's health and growth performance of lambs are essential for the sustainability of livestock production systems. This review summarized the effect of different energy levels on the ewes' health, reproductive performance of the ewes, lactation performance, embryo development and the growth of lambs, then expounded the roles of energy in later gestation. When the dietary energy of ewes in late gestation are restricted, the weight, breast development, lactation capacity, pregnancy rate will all be decreased, and the growth rate and organ development of embryos and lamb will also be restricted. 相似文献
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M. Pfuender H. Sauerwein B. Funk U. Kessler B. Barenton H. -P. Schwarz A. Hoeflich W. Kiess 《Domestic animal endocrinology》1995,12(4):317-324
The insulin-like growth factor-II (IGF-II) and the IGF-II/mannose-6-phosphate (M6P) receptor are thought to play an important role in fetal growth and development. We have studied the expression of the IGF-II/M6P receptor in fetal bovine tissues from 5 through 36 weeks' gestation. Tissues from bovine fetuses were extracted in buffer containing 2% Triton-X-100 and 2% sodium dodecyl sulfate (SDS). Aliquots of the protein extracts were analyzed by SDS polyacrylamide gel electrophoresis and the protein bands were transferred onto nitrocellulose. Immunoblotting was performed with anti-bovine IGF-II/M6P receptor antiserum. In a subset of experiments, ligand blotting was carried out with radiolabeled IGF-II and subsequent autoradiography. IGF-II/M6P receptors were expressed in all tissues examined, with the highest amount of receptor being present in fetal lung and liver. Low amounts of receptors were measured in fetal brain. The amount of receptor was developmentally regulated throughout fetal life. The developmental regulation of receptor expression varied among the different tissues. In conclusion, the IGF-II/M6P receptor is present in all fetal bovine tissues examined. The presence of the IGF-II/M6P receptor seems to be developmentally regulated during bovine fetal life. We hypothesize that this receptor exerts important biologic effects during fetal growth and tissue and organ development. 相似文献
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Lenard ZM Hopper BJ Lester NV Richardson JL Robertson ID 《Australian veterinary journal》2007,85(6):222-225
Different sonographic criteria have been developed to estimate canine fetal age, including fetal mensuration and assessment of fetal organ development. This retrospective study assessed the accuracy of gestational age and litter size predictions in 76 bitches using one of two techniques. The first method used the differential features of fetal organ development that occur in early and mid pregnancy, based on published tables for beagles. The second method used biparietal head and trunk diameters to predict gestational age based on tables published for late gestational Labrador Retrievers. The accuracy of the two methods was compared and the effect of maternal body weight and litter size evaluated. Litter size and maternal body weight did not affect the accuracy of gestational age prediction. Using a combination of both methods, the overall accuracy of predicting parturition date within 65 +/- 1 day and +/- 2 days was 70.8% and 86.1%, respectively. The correct litter size was predicted in 65% of cases, and in 89.5% of cases for +/- 1 pup. Pearson's correlation between actual litter size and predicted litter size was high (R = 0.957, P < 0.001). The organ development method of predicting gestational age was more accurate than late gestational fetal mensuration (P = 0.019). The optimum time for sonographic estimation of fetal age and litter size is early and mid pregnancy. 相似文献
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宫内发育迟缓（intrauterine growth retardation,IUGR）是指胚胎或其器官在怀孕期间生长和发育受阻,表现为后代生长发育受限或停滞。初生低体重或极低体重是IUGR仔猪的主要特征。IUGR严重影响新生仔猪的存活和后期的生长发育。诱发IUGR的原因包括母体在妊娠期间养分摄入不足、发病、环境应激以及子宫和胎盘功能异常等。猪作为多胎家畜,受IUGR影响最为严重,主要原因在于妊娠期间母猪无法提供足够的养分满足子宫角上所有胎儿正常生长发育的需要。胎盘作为母子之间唯一的联系,胎盘营养物质能否正常转运与代谢是影响胎儿发育的重要因素。碳水化合物是胎儿宫内发育最主要的能量底物,胎盘的糖类转运及代谢异常对IUGR的形成至关重要。在糖代谢的过程中,葡萄糖、磷酸戊糖和果糖可以通过葡萄糖转运蛋白、胎盘滋养层细胞和血管生成等对仔猪宫内发育起到调控作用。文章阐述了胎盘糖代谢对仔猪宫内发育迟缓的调控作用,以期为减少IUGR发生及改善IUGR仔猪的生长发育提供科学依据。 相似文献
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Noninvasive monitoring of fetal growth and development in the Siberian polecat (Mustela eversmanni).
J Wimsatt J D Johnson R H Wrigley D E Biggins J L Godbey 《Journal of zoo and wildlife medicine》1998,29(4):423-431
The Siberian polecat (Mustela eversmanni) is the preferred species to assess procedures and establish normative values for application in the related and endangered black-footed ferret (Mustela nigripes). This study was undertaken to physically, ultrasonographically, and radiographically evaluate fetal development in a spontaneously breeding captive Siberian polecat population. Ultrasonographically, fetal sac enlargement allowed presumptive pregnancy detection as early as 12 days of gestation, the fetal pole was the first definitive sign of pregnancy at about 18 days of gestation, when the fetal heart beat also appeared, and definitive pregnancy detection by ultrasound was essentially 100% accurate after 18 days. The estimation of fetal number by ultrasound was less reliable than by radiography, as it is in other litter-bearing species. Crown-rump growth, organ differentiation, and calcification patterns resembled those of domestic carnivores except that comparable developmental stages in polecats occurred at disproportionately later times, suggesting that young Siberian polecats are delivered in a less developed state. Careful palpation permitted detection of pregnancy after day 17 but with less certainty than with ultrasound. Radiographic evaluation was insensitive and of limited value for pregnancy detection until near term. Litter number and fetal detail were difficult to assess until ossification could be observed, 3-6 days before parturition. 相似文献
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绒毛用羊绒毛生长和生殖活动均有周期性,受到多种因子的调控。胰岛素样生长因子(insulin-like growth factor,IGF)作为一类多肽类生长因子,参与细胞有丝分裂、细胞增殖分化和抗凋亡过程,在毛囊上皮和真皮细胞增殖分化、卵泡发育、卵母细胞成熟、卵泡闭锁和胎儿生长发育等过程中也发挥重要作用。对IGF系统及其对绒毛用羊的绒毛生长、卵泡发育和闭锁以及胎儿发育调控方面的研究进展进行了综述,以期为进一步研究IGF调控绒毛用羊重要性状提供参考。 相似文献