Placental function and structure at term is altered in broodmares fed with cereals from mid-gestation.

This study indicates that feeding pregnant horses with cereals can change the structure and performance of the placenta, which in turn may increase the mother’s insulin resistance and composition of foal metabolism.

Objective and Methodology

• The research was designed to investigate whether feeding pregnant horses (broodmares) with cereal concentrations from the middle of their gestation period affects the structure and function of their placenta at the last stage of pregnancy.
• A total of 22 multiparous mares were grouped into two; the first group was fed only forage (F group) and the second were provided with forage and cracked barley (B group).
• Neither the weight of the foals and placentas nor the biometry of the placenta showed any substantive difference between the two groups.
• A detailed examination of the placental samples was conducted using stereology to understand the histological structure. Also, an RNAseq analysis was performed on nine placentas each from both groups. The result was then processed using the Gene Set Enrichment Analysis (GSEA) software for analyzing the enrichment of gene sets. The GSEA used the KEGG and GO database.

Findings

• Research findings showed a decrease in the volume of microcotyledonary vessels in mares fed with barley, and there was also an observed thickening of the vascular wall of allantoic arterioles.
• Additionally, there was a down-regulation in gene sets responsible for the transport of folate, neutral amino acids, anions as well as fatty acids, cholesterol, and folate degradation. On the other hand, gene sets related to RNA expression, inflammation, and vascularization were up-regulated.
• Therefore, the study indicates a relationship between how the diet of pregnant mares is managed and the potential of inducing changes in placental functions and structure, as seen in cases of maternal insulin resistance among other species.

Conclusion

• This research provides tangible evidence that diet, particularly the introduction of cereal concentrates from mid-gestation, influences the structure and functionality of the placenta in broodmares.
• These findings may have implications for equine management practices and veterinary medicine. Further studies may investigate how and why these dietary changes influence equine placental structures and the potential health and metabolic impacts on foals.