PSIX-9 - The Effect of Endophyte-infected Tall Fescue Seed Consumption on Gut and Satiety Hormones Related to Intake in Holstein Steers

Abstract: The objective of this study was to evaluate the impact of endophyte-infected tall fescue (E+) seed, and ergovaline (ERV), on gut and satiety hormones and investigate changes in post-absorptive metabolism. Holstein steers (n=12; 260 ± 16 kg) were assigned to one of three treatments (ERV concentration in diet dry matter): 0, 1.8, and 2.7 ppm with animals being adapted to an indoor environment for 4 days followed by a 7-day diet adaptation and a 10-day treatment period. On days 16 and 17, blood was collected via jugular catheters at 20-min intervals for 8 hours beginning 1 hour pre-feeding. Plasma was extracted and analyzed for insulin, leptin, and active ghrelin. Non-esterified fatty acids (NEFA), b-hydroxybutyrate (BHB), and glucose were analyzed to evaluate changes in postabsorptive metabolism using plasma from each 60-min interval. DMI decreased linearly with increased ERV concentration (P< 0.0001). A quadratic increase was observed for insulin with the 2.7 ppm ERV treatment having the greatest concentrations (P< 0.0001). A quadratic response was observed for leptin where the 1.8 ppm ERV treatment had the greatest concentrations (P< 0.0001). Active ghrelin concentrations decreased linearly with increasing ERV concentrations (P=0.047). A treatment-by-time interaction was observed for NEFA (P< 0.0001) where the 1.8 ppm ERV decreased from pre-feeding to 1-hour post-feeding and did not differ from control thereafter whereas, the 2.7 ppm ERV treatment increased above the 0 ppm ERV treatment beginning 5 hours post-feeding and was greatest among all treatments at 6 hours post-feeding. The 2.7 ppm ERV treatment exhibited the least BHB concentrations (P=0.029). Glucose concentrations increased linearly with increasing ERV concentrations (P=0.046). These results indicate that consumption of E+ seed decreases intake which may be possible through alteration of hormones and may also alter post-absorptive metabolism.