Animals. Immediately after the end of Exp. 1 (d 14),
the same heifers (mean BW = 456 ± 14 kg) received
a new CIDR and were evaluated via transrectal ultrasonography
(5.0-MHz transducer, 500V; Aloka) to confi
rm the absence of a corpus luteum. None of the heifers
ovulated and developed a corpus luteum during Exp. 1
and were therefore immediately assigned to Exp. 2 (d
14 to 28).