The Effect of Seasonal Changes in Non-Structural Carbohydrates in Pasture on the Metabolic Profile of Horses with Laminitis

This study aimed to examine the seasonal dynamics of non-structural carbohydrates in pasture and their relationship to metabolic indicators in horses with a history of laminitis. Thirty Hucul mares were divided into a laminitis group (LG, <i>n</i> = 15) and a control group (CG, <i>n</i> = 15). Insulin, glucose, fructosamines concentrations and body weight were monitored during four sampling periods (S0-S3), while pasture variables were analyzed during three periods (S1-S3). The concentration of water-soluble carbohydrates was highest in May (126.8 g/kg DM) and measured lower in October (57.9 g/kg DM), while starch concentrations measured 0.1 g/kg DM in May, 25.8 g/kg DM in July, and 24.0 g/kg DM in October. No significant differences were observed in insulin concentrations between groups (<i>p</i> > 0.05). Glucose was significantly higher in LG in May (LG: 5.50 mmol/L; CG: 5.09 mmol/L; <i>p</i> < 0.05) and October (LG: 5.98 mmol/L; CG: 5.24 mmol/L; <i>p</i> < 0.01). Fructosamine values were higher in LG throughout the season, with significance in October (LG: 120.6 μmol/L; CG: 101.1 μmol/L; <i>p</i> < 0.05). Body weight increased in both LG and CG during grazing (S2), with mean values at S0 being 423.6 kg in LG and 424.8 kg in CG, and at S2 being 533.8 kg in LG and 535.6 kg in CG (<i>p</i> > 0.05 for between-group differences). These findings suggest a different glycemic response in laminitic horses in relation to WSC and starch concentrations and highlight starch as a potential predictor of glycemic instability.