Maternally derived amino acids (AA) are essential for early conceptus development, and specific transporters enhance histotrophic AA content during early ruminant pregnancy. In the present study we investigated AA transporter expression in early equine conceptuses and endometrium, during normal pregnancy and after induction of embryo-uterus asynchrony. 'Normal' conceptuses and endometrium were recovered on Days 7, 14, 21 and 28 after ovulation. To investigate asynchrony, Day 8 embryos were transferred to recipient mares on Day 8 or Day 3, and conceptuses were recovered 6 or 11 days later. Endometrial expression of AA transporters solute carrier family 38 member 2 (SLC38A2), solute carrier family 1 members 4 and 5 (SLC1A4 and SLC1A5) increased during early pregnancy, whereas solute carrier family 7 member 8 (SLC7A8), solute carrier family 43 member 2 (SLC43A2) and solute carrier family 7 member 1 (SLC7A1) SLC7A8, SLC43A2 and SLC7A1 expression decreased and the expression of solute carrier family 1 member 1(SLC1A1) and solute carrier family 7 member 2 (SLC7A2) was unaffected. In conceptus membranes, most transporters studied were upregulated, either after Day 14 (solute carrier family 7 member 5 - SLC7A5, SLC38A2, SLC1A4, SLC1A5 and SLC7A1) or Day 21 (SLC43A2 and SLC7A2). Asynchronous ET indicated that endometrial SLC1A5, SLC1A1 and SLC7A8 are primarily regulated by conceptus factors and/or longer exposure to progesterone. In conclusion, AA transporters are expressed in early equine conceptus membranes and endometrium in specific spatiotemporal patterns. Because conceptuses express a wider range of transporters than the endometrium, we speculate that the equine yolk sac has recruited AA transporters to ensure adequate nutrient provision during an unusually long preimplantation period.
Background: Overfeeding is associated with obesity and insulin dysregulation (ID), which are both risk factors for equine metabolic syndrome. How chronic overfeeding affects development of these factors is poorly understood.Objectives: To examine the influence of long-term high-energy diet provision on body condition and ID.Animals: Eleven Shetland pony mares.
Methods:In a 3-phase study, the high-energy group (n = 7) was fed 200% of net energy (NE) requirements (hay; concentrate: 36% sugar and starch, 13% fat) for 24 weeks, followed by 17 weeks hay-only feeding before resuming the high-energy diet (n = 4) for an additional 29 weeks. Mares were weighed weekly. Oral glucose tolerance tests were performed 3 to 4 times per dietary period. Results were compared with those of a control group (phase 1, n = 4; phases 2 and 3, n = 6) that received 100% NE requirements, using a general linear mixed model with post hoc Bonferroni testing.Results: The mean body weight of the high-energy group increased by 27% per highenergy feeding period. During both feeding periods, area under the curve (AUC) for plasma glucose concentration decreased (P < .01), whereas AUC for plasma insulin concentration increased. Mean basal plasma glucose concentration and peak plasma insulin concentrations were higher (P < .05) in the high-energy group than in the control group.Conclusion and Clinical Importance: Feeding a high-energy diet to healthy nonobese Shetland pony mares led to more efficient glucose metabolism within 5 weeks, followed by significant hyperinsulinemia and obesity. Hyperinsulinemic status was
Obesity has been associated with altered reproductive activity in mares, and may negatively affect fertility. To examine the influence of long-term high-energy (HE) feeding on fertility, Shetland pony mares were fed a diet containing 200% of net energy (NE) requirements during a three-year study. The incidence of hemorrhagic anovulatory follicles (HAF) and annual duration of cyclicity were compared to those in control mares receiving a maintenance diet. Day-7 embryos were flushed and transferred between donor and recipient mares from both groups; the resulting conceptuses were collected 21 days after transfer to assess conceptus development. HE mares became obese, and embryos recovered from HE mares were more likely to succumb to early embryonic death. The period of annual cyclicity was extended in HE compared to control mares in all years. The incidence of HAFs did not consistently differ between HE and control mares. No differences in embryo morphometric parameters were apparent. In conclusion, consuming a HE diet extended the duration of cyclicity, and appeared to increase the likelihood of embryos undergoing early embryonic death following embryo transfer.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.