Impact of Endometrial Lipids on Uterine Histotroph Composition and Preimplantation Conceptus Development in Dairy Cattle

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Reproduction is a critical component of dairy sustainability because it impacts the overall milk yield in a herd and its' production efficiency. Pregnancy loss in lactating cows, however, is substantial and impairs reproductive efficiency and profitability of dairy farms. Elongation of the preimplantation conceptus (embryo and associated extra-embryonic membranes) is a prerequisite for successful pregnancy in cattle and depends on histotroph secretion by the endometrium. Nonetheless, approximately one third of viable blastocysts fail to elongate and survive by the end of the fourth week of development. Improvements in reproductive efficiency of dairy cows will require the development of strategies to minimize early embryonic mortality, which in turn will require a better elucidation of critical events in early developmental biology. Recently, our research group investigated the metabolome of uterine histotroph and the transcriptome of conceptus cells during the process of elongation. Our results demonstrated that the histotroph is rich in lipids, and suggest that significant changes in gene expression of conceptus cells are likely coordinated by lipids through activation of transcription factors and cell signaling. The bovine endometrium accumulates lipids from the time of fertilization of the oocyte to the onset of conceptus elongation 14 days later, and likely provides the main source of lipids for the developing conceptus. However, detailed information on lipid composition in the endometrium and its importance for histotroph composition and conceptus development are unavailable. The long-term goals of the proposed research program are to understand the importance of endometrial lipids for preimplantation conceptus development and survival in lactating dairy cows, and to develop nutraceutical strategies to reduce pregnancy losses and improve reproductive efficiency of dairy herds. The specific objectives of this research program are 1) to investigate how and what lipids are accumulated in the bovine endometrium by the time of initiation of conceptus elongation; 2) to investigate how and what lipids are transferred from the endometrium to the developing conceptus during the elongation phase; 3) to evaluate the impact of specific lipids on the biology of conceptus cells; and 4) to develop a nutraceutical supplement capable of enriching the endometrium of lactating cows with target lipids that would favor conceptus development and survival.