Insulin responses during glucose tolerance tests in steers with increasing Wagyu genetic influence

Intravenous glucose tolerance tests (IVGTT) were conducted in 18 steers with 0, 50 and 75% Wagyu genetic influence. Glucose clearances were similar for all steers. Plasma insulin concentrations (basal, 5 and 10 min post-infusion) were higher (P < 0.05) in 0% Wagyu steers (2.57, 7.36, 9.68 ng mL−1) relative to 50% Wagyu (1.17, 2.59, 5.34 ng mL−1) or 75% Wagyu (0.99, 2.78, 5.00 ng mL−1). A correlation coefficient of 0.71 (P = 0.005; n = 15) between marbling score of carcasses and plasma glucose concentration 90 min after glucose infusion suggests, possible associations among the propensity of cattle with Wagyu genetic influence to marble, mechanisms of glucose utilization and nature of the insulin response to circulating glucose. Key words: Plasma glucose, insulin, marbling, Wagyu