The effects of feeding frequency on glycemia and insulinemia in moderately exercised young horses.

Concentrates are typically fed twice daily to supplement forages in horses to facilitate management, especially those with higher energy needs, but high-grain meals can contribute to digestive and metabolic challenges, including insulin dysregulation. This study investigated the effects of feeding frequency on glycemia, insulinemia, and insulin sensitivity measured by an oral sugar test in moderately exercised young horses. Thirty-two healthy Quarter Horses (2-3 years old) were assigned to either traditional feeding (TF; two grain meals/day) or fractioned feeding (FF; automated grain delivery every hour for 10 h/day), with grain comprising 40% of daily dry matter intake and forage 60%. Oral sugar tests (OST) were conducted at baseline and after 30 and 60 days of treatment. On day 45, a subset of horses (n = 10) completed an 8-h postprandial glucose and insulin assessment; plasma basal cortisol was also measured at 0, 30 and 60 days. OST results showed elevated 75-min insulin on day 30 for both treatments (P < 0.001). During the 8-h postprandial test, TF horses exhibited higher glucose and insulin peaks than FF horses(P < 0.030). Area under the curve for insulin (AUC) was higher (P = 0.032) in TF than FF at 60 and 180 mins, indicating greater postprandial insulinemia with larger, less frequent meals. Total AUC for insulin was lower (P = 0.006) in FF horses (1119.04 ± 102.30 μIU·min/mL) compared to TF horses (1406.00 ± 160.8 μIU·min/mL). These findings suggest that fractioned feeding attenuates postprandial insulin responses due to a lower non-structural carbohydrate (NSC) load per meal and therefore warrants direct testing when managing horses at risk for insulin dysregulation or hyperinsulinemia-associated laminitis. This finding could be another tool to manage insulin dysregulated horses.