Effect of Overfeeding Shetland Pony Mares on Embryonic Glucose and Lipid Accumulation, and Expression of Imprinted Genes.
Authors: D' Fonseca Nicky M M, Gibson Charlotte M E, van Doorn David A, Roelfsema Ellen, de Ruijter-Villani Marta, Stout Tom A E
Journal: Animals : an open access journal from MDPI
Summary
Maternal nutrition during the periconceptional period exerts profound effects on embryonic epigenetics in horses, yet this remains poorly characterised in equine species despite evidence from other mammals that overfeeding can disrupt imprinted gene expression and alter fetal programming. Shetland pony mares were assigned to either high-energy (200% of maintenance) or control feeding regimens, inseminated, and their day-seven embryos transferred to recipient mares from either the same or opposite dietary group, allowing researchers to distinguish intrinsic embryonic effects from those imposed by the recipient environment. Embryos originating from overfed mares but gestated in control recipients exhibited significantly upregulated expression of multiple imprinted genes (including IGF2, H19 and GRB10) alongside increased expression of glucose and amino acid transporters in the conceptus membranes at day 28, suggesting that maternal overfeeding imprints lasting molecular changes despite subsequent normalisation of the gestational environment. Notably, these alterations in gene expression occurred without detectable changes in lipid accumulation or glucose uptake at the measured timepoints, indicating that epigenetic dysregulation may precede observable metabolic dysfunction. For equine practitioners, these findings highlight the critical importance of appropriate periconceptional nutrition in breeding mares and raise questions about whether such molecular alterations persist through gestation and into postnatal life, potentially affecting long-term metabolic and growth characteristics of offspring.
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Practical Takeaways
- •Overfeeding pregnant mares during early gestation may cause lasting epigenetic changes in the developing embryo that could affect offspring health; maintain mares at appropriate body condition rather than providing excess calories
- •The alterations in gene expression observed at day 28 may persist through gestation and into postnatal life—long-term follow-up studies are needed before making definitive management recommendations
- •Nutritional management during the periconceptional period warrants careful attention in breeding programs, particularly in nutrient-dense breeds like Shetland ponies prone to metabolic challenges
Key Findings
- •Maternal overfeeding (200% of energy requirements) elevated expression of imprinted genes IGF2, IGF2R, H19, GRB10, PEG10, and SNRPN in day-28 conceptus membranes
- •DNA methyltransferases DNMT1 and DNMT3B expression increased following embryo transfer from high-energy to control diet mares
- •Glucose and amino acid transporter expression (SLC2A1, SLC2A5, SLC7A2, SLC1A5, SLC7A1) was elevated in conceptus membranes and recipient endometrium
- •Maternal overfeeding did not significantly affect lipid droplet accumulation in blastocysts or glucose uptake by day-28 membranes