Sequential changes in serum protein profiles in pregnant Spanish purebred mares

This study investigates sequential changes in serum protein fractions during gestation in 31 pregnant Spanish Purebred mares compared to 15 non-pregnant control. Total serum proteins (TSP) were measured using the Biuret method, while albumin (ALB), total globulins (tGLOB), and their subfractions (α₁, α₂, β₁, β₂, γ-GLOB) were analyzed by agarose gel electrophoresis. Pregnant mares showed significant changes in serum protein profiles throughout gestation. TSP and tGLOB concentrations increased from mid to late pregnancy (months 6-11), while ALB concentrations declined between months 6-8 and rose again from months 9-11 (p ≤ 0.05). The ALB/GLOB ratio was lower in pregnant mares during months 6-9. α₁- and α₂-GLOB concentrations remained consistently elevated across all gestational stages (p ≤ 0.05). β₁-GLOBs exhibited stage-specific fluctuations, whereas β₂-GLOBs remained stable. γ-GLOB followed a triphasic pattern: an early increase (months 1-4), a mid-gestation decline (months 5-6), and a late gestation rise (months 7-11) (p ≤ 0.05). These results underscore dynamic, stage-dependent shifts in serum protein fractions during equine pregnancy. The progressive increase in α₁-, α₂-, and γ-GLOBs suggests heightened immune activity and preparation for passive immunity transfer. Changes in ALB and β₁-GLOBs likely reflect metabolic and transport adaptations. Electrophoretic profiling of serum proteins may offer a valuable approach for monitoring maternal and fetal health throughout gestation.