Figure 1

Luteal cross-sectional area and plasma progesterone concentration in cows of group 1 and 2 . Luteal cross-sectional area in cows of group 1 (n = 7, ─○─) and in cows of group 2 that did not respond to PGF on day 5 (n = 3, ─Δ─) and plasma progesterone concentration in cows of group 1 (n = 7, · ○ ·) and in cows of group 2 that did not respond (n = 3, · Δ ·) from day 2 to day 9 after PGF. * Significant difference between the two groups in their luteal cross-sectional area.