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

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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.