Gilts were housed in pens until approximately 10 days
before the insemination, when they were transferred to
individual crates. Estrus detection was performed with
boars older than 12 months of age introduced into the pen,
for 20 min, once a day. While the boar was present, gilts
were checked for signs of estrus, either in pens or in crates.
Gilts which showed a standing reflex, in response to the
backpressure test, were considered to be in estrus. Gilts
were inseminated on average with 229 14 days of age, at
their second or further estrus