The objective was to evaluate the differences on metabolism profile between animals subjected to short and long-term synchronization protocols. Thirty-seven non pregnant hair sheep were used and randomly allocated into two different groups. Group A, (n=20) on day 0 (D0) of the protocol received an intravaginal sponge impregnated with 60 mg of medroxyprogesterone acetate (MAP®), and on day 7 the sponge was removed and 0.0375mg of D-cloprostenol (Prostal®), 300 IU equine chorionic gonadotropin (eCG, Novormon®) were injected. Group B, (n=17) on D0 the sponge was placed, and it was removed 14 days later, together with the application of 300 IU of eCG. The animals were inseminated by laparoscopy between 52 and 56 h after removing the sponges. For analysis of serum metabolites, blood samples were collected on days 0, 7 y 22; y 0, 14, and 29 of the protocol for groups A and B, respectively. Serum concentrations of glucose, albumin, total plasma protein (TPP), cholesterol, urea, and blood urea nitrogen (BUN) were evaluated using IHR (Diagnostica®) kit. The data was analyzed by Chi-Square and ANOVA, using SAS version 9.4 software. No significant differences were observed between the groups (P>0.05) for the pregnancy rate. The evaluation of the metabolite profile showed that, the concentrations of TPP, albumin and cholesterol were higher in Group B (7.79±0.11; 3.36±0.04; 86.65±2.56 g/dl, respectively) compared to Group A (7.17±0.10; 2.62±0.03; 52.02±2.25 g/dl, respectively). However, no significant differences were observed between the groups for serum concentrations of urea, BUN and glucose (P>0.05). Nevertheless, the energy and protein profile of the sheep subjected to the short-term protocol was lower compared to that of the sheep subjected to the long-term protocol. More research will be needed to determine the influence of these results on embryonic survival and future development of pregnancy.