Figure 1.

Feeding protocol (A), synchronization and superstimulation protocol (B), and intensive bleeding protocol (C) from experiments 1 and 2. In both experiments, cows were presynchronized with controlled internal drug release (CIDR)-Synch (see Materials and Methods) with the last GnRH on d 0 (D0). Cows underwent superstimulation as shown while exposed to a 2 × 2 factorial of treatments: with or without feed restriction and with or without supplemental LH. Cows were exposed to either feed restriction (FR; 25% restriction of intake) or ad libitum (AL) feeding during the Feed Treatment period (A). All FSH injections were supplemented with low LH, whereas the last 4 were supplemented with either high (H) or low (L) LH during LH Treatment (B). Cows then received AI with subsequent uterine flushing. Resynchronization was then performed (B) using CIDR-Synch, follicular ablation (Foll. Abl.), and subsequent superstimulation for period 2 (experiment 1), and periods 2, 3, and 4 (experiment 2). During period 2 of experiment 2, intensive blood sampling (BS) occurred following the second, fourth, sixth, and eighth injections (C). HCG = human chorionic gonadotropin.