im if a CL or a follicle 13 to 19 mm in
diameter was present. Cows received a second treatment of
100 mg GnRH im, 2.5 days after PGF. If structures were not
observed on the day PGF was scheduled, cows were
restarted with GnRH with or without a controlled internal
drug releasing device (Pfizer). Some of these cows eventually
re-entered the study.
For TAI, cows were bred 18 hours after the second GnRH
injection with X-sorted sperm or nonsorted semen. Cows
selected for TET received an embryo 1 week later. Embryos
were transferred 7.5 to 8.0 days after oocyte fertilization for
recipients with a CL detected by ultrasonic examination.
Cows were given a caudal epidural (5 mL of 2% [wt/vol]