However, glucose supplementation also increases circulating
concentrations of other hormones associated with
reproductive and hepatic function, including glucose itself
and IGF-I (Jones and Clemmons, 1995; Schroeder
et al., 2006). Therefore, we hypothesized that the insulin-
stimulated decrease in hepatic P4 catabolism may
also be dependent on circulating glucose and IGF-I. On
the basis of this rationale, 3 experiments were conducted
to evaluate plasma concentrations of glucose, insulin,
IGF-I, and P4 in beef females receiving exogenous insulin,
insulin plus glucose, or ST.