Few studies evaluating protocols for fixed-time artificial insemination (FTAI) in gilts have been performed .
The use of a single hormone for FTAI protocols in pubertal gilts can be difficult because they are in different phases of the oestrous cycle. This is in contrast to scenario of FTAI in weaned sows, for which several hormonal protocols to induce follicle growth and ovulation are available. Protocols proposed for FTAI in gilts involve the use of progesterone (P4) analogue, followed or not by the use of eCG, to stimulate follicle growth, and an ovulation inductor such as GnRH, hCG or porcine luteinizing hormone – pLH , the use of pLH is more efficient than hCG to induce ovulation after using P4 analogue and eCG in pubertal gilts. Embryo survival has not been impaired in gilts submitted to a double FTAI, after the use of P4 analogue and GnRH, compared to gilts inseminated according to the onset of oestrus . The reproductive performance of gilts with double FTAI after synchronization with P4 analogue followed by eCG and pLH application was similar to that of a control group in which multiple inseminations were performed. In weaned sows, the use of pLH at oestrous onset followed by a single FTAI 24 h later resulted in similar reproductive performance to that obtained with multiple inseminations without pLH application .