Discussion
Promising results concerning farrowing rate were obtained using protocols that included the use of pLH at oestrous onset and a single fixed-time insemination in gilts. As far as we know, this is the first study in which a
reduced pLH dose (2.5 mg) was tested by the vulvar submucosal route. Its use at oestrous onset was successful in increasing the percentage of gilts ovulating within 24 h after pLH application. Although the reduction in the IOEO was slight (4 h), it is similar to that observed using more complex protocols (6 h), which involved the use of progesterone, eCG and pLH(Degenstein et al. 2008). The higher diameter of follicles observed in VS2.5FTAI gilts might be related to better
follicle growth and, consequently, earlier maturation of follicles, explaining the advancement of ovulation.
Dose reduction by the vulvar submucosal route compared with the intramuscular route was described for prostaglandin analogues in swine (Kirkwood et al. 1996;