The role of maternal energy metabolism on lipogenesis in the prenatal piglet

商品猪遗传和管理方面的进步成功地增加了产仔数。然而，不幸的是，产仔数的增加导致平均出生体重的下降和死亡率的增加。仔猪出生时脂质储备非常低，特别是低出生体重仔猪，这可能导致高死亡率。猪和人怀孕的特点都是母体组织最初体重增加，随后在妊娠后期进入分解代谢状态，此时母体组织被动员起来用于胎儿生长。妊娠后期的另一个特征是胰岛素抵抗（IR）。母体组织中的胰岛素抵抗意味着营养物质会优先流向快速生长的胎儿。该计划的总体假设是，如果能够在维持母体组织IR的同时获得母体血浆前体浓度（葡萄糖和脂质）的增加，则新生仔猪的脂肪生成将得到改善。我们进一步假设这将提高仔猪的活力和存活率。该计划最初5年的研究将实现3个目标。第一个目标是确定限制商品猪品种产前仔猪脂肪生成的分子途径。这将通过比较商品猪品种的母猪和仔猪与梅山遗传至少50%的母猪和仔猪的脂质代谢相关分子（脂质组）来完成。梅山猪是一个传统的猪品种，其特点是体脂极高。本研究的结果将为后续实验中测量的标记提供信息。第二个目的是确定妊娠早期的高脂肪饮食是否会增加妊娠后期分解代谢状态下循环的母体脂肪生成前体，同时维持IR，从而将这些前体分配给发育中的胎儿。最终目的是确定仔猪出生体重和体内脂质含量的增加是否能提高仔猪的活力、存活和生长。总体而言，养猪户可以利用本项目获得的数据来降低仔猪死亡率，从而提高经济和环境的可持续性，提高效率。此外，考虑到人与猪之间的异同，这些数据可以为饮食对IR的作用以及对发育中的胎儿的影响提供信息。未来的研究可以关注不同能量来源、碳水化合物和脂质的作用，并进一步阐明IR在妊娠后期对胎儿发育的作用。

Advances in genetics and management in commercial swine has successfully resulted in increased litter size. Unfortunately however, increased litter size results in decreased average birth weight and increased mortality. Piglets are born with very low lipid reserves, especially low birth weight piglets and this may contribute to the high mortality. Pregnancy in both swine and humans is characterized by an initial weight gain in the maternal tissues followed by a catabolic state in late gestation when maternal tissues are mobilized and used for fetal growth. Another feature of late gestation is insulin resistance (IR). Insulin resistance in the maternal tissues means that nutrients will be preferentially directed to the rapidly growing fetuses.  The overall hypothesis of this program is that lipogenesis in the neonatal piglet will be improved, if increased maternal plasma precursor concentrations (glucose and lipids) can be obtained while maintaining IR in the maternal tissues.  Further we hypothesize that this will improve piglet vitality and survival.   The studies outlined for the initial 5 years of this program will fulfill 3 objectives. The first objective is to identify the molecular pathways limiting lipogenesis in prenatal piglets from commercial swine breeds. This will be accomplished by comparing molecules associated with lipid metabolism (lipidome) from sows and piglets of a commercial swine breed to sows and piglets with at least 50% Meishan genetics. The Meishan is a traditional swine breed characterized by extremely high body fat. Results from this study will inform markers to be measured in subsequent experiments. The second objective is to determine if a high fat diet in early gestation will increase circulating maternal lipogenic precursors during the catabolic state in late gestation while maintaining IR, thus partitioning these precursors to the developing fetuses. The final objective, will be to determine if increases in piglet birth weight and lipid content in the body improves piglet vitality, survival and growth.  Overall, the data obtained in this project can be utilized by swine producers to reduce piglet mortality, thus improving economic and environmental sustainability with increased efficiencies. Moreover, considering similarities and differences between humans and swine, the data can provide information on the role of diet on IR and effects on the developing fetus. Future research can focus on the role of different energy sources, carbohydrate vs lipid and further delineation on the role of IR in late gestation on fetal development.