Fetal and maternal plasma lipids in chronically catheterized mares in late gestation: effects of different nutritional states.

This research investigated the impact of different nutritional states on plasma lipid concentrations in pregnant horses and their fetuses, showing that both short-term fasting and prolonged undernutrition result in increased maternal plasma lipid concentrations, influencing lipid levels in the fetus. However, the source of increased polyunsaturated fatty acids in the fetus under these conditions is not likely the maternal circulation, but rather the placenta or fetal tissues.

Research Methodology

• The research was conducted by implanting maternal and fetal arterial catheters into 12 pony mares, between 244-303 days into their gestation (the term considered normal for mares being 320-360 days).
• Observations were made starting from the 5th day after the catheter insertion.
• Post-surgical recovery, arterial samples were collected from the mares categorized into three groups: group IA, consisted of seven mares with normal feeding habits; group IB had four mares from IA that were observed at the end of a 30-hour fast and three hours post-refeeding; and group II involved six mares who had an inability to restore normal feeding patterns.

Research Findings

• The fatty acid concentrations and composition of different lipid fractions in the plasma (free fatty acid(FFA), triacylglycerol, and phospholipid) were analyzed.
• The results signified a significant increase in the concentration of maternal FFA, triacylglycerol, and phospholipid concentrations in mares from group IB (fasted) and group II (under-fed).
• For the fetuses, the concentrations of FFA and Phospholipid experienced a significant surge in under-fed mares (group II), though the same could not be said for the fasted mares (group IB).
• In the fetal plasma, the proportions of polyunsaturated fatty acids deriving from essential fatty acids in the FFA and phospholipid fractions exceeded those in the mare.
• Despite fasting (group IB) and undernutrition (group II), the relative polyunsaturated fatty acid amounts in each fraction remained unaltered.

Research Conclusion

• The study concluded that fluctuations in the nutritional state, like a short fast or prolonged undernutrition, resulted in an elevation in maternal plasma lipid concentrations.
• These maternal lipid levels subsequently impacted the total lipid amount in the fetal circulation.
• However, the research indicated that increases in the fetus’s polyunsaturated fatty acids (e.g., in the case of group II) did not likely originate from the maternal circulation.
• Rather, it proposed that these fatty acids’ likely sources were either the placenta or the fetal tissues.