妊娠早期日粮添加精氨酸促胎猪生长及其代谢程序化机制

The low rate of embryonic/fetal survival is a major issue in the global swine industry, but currently there are no practical nutritional solutions to this problem. We propose to ameliorate this problem by targeting key cellular signaling pathways through dietary arginine supplementation. Under current feeding systems, the diet of gestating swine does not provide adequate arginine, a nutrient that is essential to the biosyntheses of nitric oxide and polyamines, as well as embryonic/fetal survival.Based on results of our preliminary studies, we hypothesize that (1) supplementing 0.5-1% arginine to the corn- and soybean meal-based diet of pregnant gilts between Days 14 and 35 of gestation may stimulate the mTOR signaling pathway and, therefore, protein synthesis in the placenta and embryo/fetus, resulting in their improved growth, development and survival; and (2) optimizing maternal arginine nutrition may beneficially regulate expression of genes in the fetus that are related to nutrient metabolism and protein accretion in offspring, thereby increasing growth performance and feed efficiency of the progeny. These hypotheses will be tested using proteomic, metabolomic, stable isotope tracing, placental cell culture, and epigenetic techniques. Findings from this project are expected to not only provide new fundamental knowledge about amino acid nutrition but also have important implications for enhancing embryonic/fetal survival and the economic returns of swine production in China and worldwide.

在中国的养猪生产中,低胚胎/低胎儿存活率和胎儿的生长受限是个严重的问题，但目前没有解决这个实际问题的营养措施。我们期望通过用功能性氨基酸(精氨酸)对信号通路和靶代谢过程调控来解决这一难题。目前的饲喂体系，妊娠母猪日粮不能提供充足的精氨酸。我们的科学研究假设是:（1）增加妊娠母猪日粮中精氨酸的供给，可以刺激mTOR通路以及胎盘和胎儿蛋白质的合成，从而促进胎盘的生长和功能，提高胎儿的存活率和生长速率；（2）改善母体精氨酸营养能调控后代代谢和生长的胎儿基因的表达, 从而提高后代生长性能和饲料利用率。本研究拟通过蛋白质组学和代谢组学技术，稳定同位素技术，建立胎盘细胞系和表观遗传学技术探讨精氨酸增加胎猪存活率和改善出生后小猪存活生长的机理，对促进国民经济发展具有重要意义。

在猪生产中，胚胎损失是影响猪生产效率的重要因素之一，但目前没有解决这个实际问题的营养措施。该项目中，我们通过在妊娠14天－25天给母猪饲喂精氨酸研究其对胚胎生长及存活的影响。同时，我们研究了腐胺——这一精氨酸代谢物对胚胎及胎儿生长调节的机制。研究结果显示，在妊娠14天－25天日粮添加0.4%或0.8%的精氨酸可提高母猪血浆中精氨酸的浓度、总羊水体积、尿囊液及羊水中精氨酸含量、羊水中总果糖及氨基酸含量、胚胎生长及提高每窝活胚胎数2个。腐胺可通过激活哺乳动物雷帕霉素靶标（mechanistic target of rapamycin, mTOR）相关信号通路蛋白表达促进猪胚胎滋养层细胞蛋白质合成。因此，在妊娠14天－25天母猪日粮添加0.4%或0.8%的精氨酸，或给妊娠母猪日粮添加腐胺，可为猪生产中提高胚胎／胎猪存活与生长提供新的策略。