Trios were formed with gilts
that showed oestrus in the same shift or no more than 8 h later. The time of insemination was
based on results of a previous pilot study in which 80%
of the gilts ovulated between 16 and 40 h after receiving
5 mg pLH at oestrous onset, by the intramuscular route
(R.R. Ulguim, unpublished data).