76 Digestibility of a Diet with or Without Reed Sedge Peat in Exercised Horses

An experiment was conducted to determine the effect of a concentrate diet containing Reed Sedge Peat (RSP) on nutrient digestibility, and serum glucose and insulin concentrations in mature exercised horses. The addition of RSP to the diet may effect nutrient digestibility and glucose metabolism in exercising horses. Six stock-type geldings (μ 546 kg), ranging from 8 to 19 yr of age, were fed a diet consisting of coastal Bermudagrass hay and a concentrate with or without RSP in a duplicated 3 × 3 Latin-square design. Three dietary treatments consisted of: control, no RSP (C); 10 lb/ton RSP (RSP10; Kent Nutrition Group, Muscatine, IA); and 20 lb/ton RSP added (RSP20). The 12-wk study consisted of 3 21-d adjustment periods followed by a 3-d fecal collection period. Total feces voided was collected every 4 h. Blood was collected 30 min pre-feeding, 30 min post-feeding, 8 h post-feeding, 30 min pre- Standard Exercise Test (SET); then 30 s, and 10, 30, 60, and 120 min post-SET. Horses were fed hay at a minimum 2% body weight per day and 2.2 kg/d of each dietary treatment. Feed and feces were analyzed for dry matter (DM), crude protein (CP), ether extract (EE), acid detergent fiber (ADF), neutral detergent fiber (NDF), ash, Ca, and P concentrations. Blood serum was analyzed for fasting insulin and glucose concentrations. Data for nutrient digestibilities, and serum glucose and insulin concentrations were analyzed using theProc Mixed Procedure of SAS v. 9.4. Significant differences between means were declared at P < 0.05. There was an effect of period on apparent DM (P = 0.02), NDF (P = 0.04), ADF (P = 0.01), Ca (P = 0.03), and P (P = 0.01) digestibility. There was an effect of treatment (P = 0.03) on pre- and post-prandial serum glucose concentrations. Horses consuming RSP20 (95.5 mg/dL) had greater overall mean serum glucose concentrations compared with horses consuming RSP10 (87.2 mg/dL) and C (86.6 mg/dL). Overall post-prandial serum insulin concentrations (17.81 uIU/mL) were greater (P < 0.01) compared with pre-prandial (7.1 uIU/mL) and 8 h post-prandial (6.52 uIU/mL). Immediately following exercise, mean serum glucose concentrations decreased (P < 0.01) from 86.43 mg/mL pre-SET to 80.13 mg/dL. Serum insulin concentrations decreased (P < 0.01) from 5.56 ulU/mL pre-SET to 3.05 ulU/mL post-SET. The data suggests no benefits were observed in nutrient digestibility when RSP was added to horses’ diets. However, greater glucose concentrations with the RSP20 diet may provide more energy for performance of the horse. Therefore, further research may be warranted to investigate effects of RSP on glucose and insulin dynamics in exercising horses.