The peripartum period influenced the serum macromineral profile in mares

Abstract. Changes in metabolic requirements during pregnancy may produce nutritional imbalances predisposing mares to pathological conditions. Therefore, we aimed to examine changes in serum macrominerals during the peripartum period in mares. Fifteen pregnant mares (Group A) were monitored starting at the 263rd day of pregnancy until the 21st day after foaling. Seven non-pregnant and non-lactating mares were used as a control group (Group B). Group A was subjected to blood sampling within 24 ± 12 h after parturition (P) and then 7, 14 and 21 days after foaling (+1, +2, +3 weeks, respectively). Group B was subjected to regular sampling throughout the study to ensure that seasonal changes had no significant effect on studied parameters. Serum samples were analysed for serum electrolytes including sodium (Na⁺), potassium (K⁺), calcium (Ca^+ +), phosphorus (P⁺), chloride (Cl⁻) and magnesium (Mg^+ +). Two-way repeated measures of analysis of variance (ANOVA) was applied to evaluate significant effects of peripartum on electrolyte concentrations. Group A showed a decrease in Cl⁻ concentrations (P = 0.011) after foaling and lower P⁺ concentrations (P = 0.015) compared to Group B throughout the study. The linear regression model showed an increase in Na⁺ concentrations (P = 0.002) and a gradual decrease in serum Ca^+ + (P = 0.001) during pregnancy. Because the most significant changes in serum electrolytes occurred within 2 weeks before and 2 weeks after foaling, monitoring serum electrolyte concentrations would indicate whether the mare needs further mineral supplementation at this stage. The significant changes in a mare's macromineral profile that we observed over the peripartum provide enhanced knowledge about mineral interrelations and their modifications during specific physiological conditions such as late pregnancy and early postpartum.