Due to the advancement of ovulation, reduction of the hormonal dose and the ease of application, the vulvar submucosal route would be the best option for FTAI protocols, but their negative impact on litter size remains to be elucidated. Taking
into account the good fertility results obtained in IM5FTAI gilts whose ovulation was not advanced, the possibility of a
single FTAI without any hormonal treatment should be further investigated, to establish reliable FTAI protocols for
gilts.