Short Supply of High Levels of Guanidine Acetic Acid, a Creatine Precursor, Alters Ovarian Artery Flow and Improves Intraovarian Blood Perfusion Area Associated with Follicular Growth in Sheep

Little is known about the role of guanidine acetic acid (GAA), a precursor of creatine, in the reproductive function of ruminants. Therefore, this study aimed to contribute initially to this area by supplementing the diets of ewes with a high dose of GAA evaluating its effects on reproductive response. Twenty adult sheep had their estrus synchronized using an MPA sponge, eCG and PG2α. After estrus detection ewes were mated. For 10 days until mating, ewes were grouped in baseline diet (BSD; n = 10), and a GAA diet (GAAD; n = 10), which was the BSD with daily 0.9 g/kg DM of GAA. After the eCG+PG2α dose, the GAAD group exhibited an increase in the peak diastolic and pulsatility of the ovarian artery, a reduction in the systolic/diastolic peaks ratio and a larger intraovarian blood perfusion area. A greater depletion of follicles with < 3 mm was observed in the GAAD group, and a higher number of follicles ≥ 3 mm. No differences were observed between the diets respect to pregnancy, and twin rates. Thus, a high GAA supply before mating significantly alters ovarian vasculature and improves follicular growth in ewes but does not affect the pregnancy rate.