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Non-esterified fatty acids (NEFAs) and Insulin-like growth factor-I (IGF-1) concentrations are modified after the induction of a "male effect". The present study examined the effect of the introduction of males into a group of females that were previously isolated from males, during different phases of the sexual cycle, to determine the changes to the NEFAs and IGF-1 concentrations. Sixty-four does were divided into six groups. The males were introduced with the females at different points after sponge removal. Introduction was carried out 48 h (n = 10, Group 48H), 72 h (n = 12, Group 72H), 4 days (n = 10, Group 4 D), 13 days (n = 10, Group 13 D) or 18 days after sponge removal (n = 10, Group 18 D), and a control group was implemented that had no contact with males (n = 12, Control Group). Plasma samples were taken every day to determine daily progesterone (P4) and NEFAs concentrations, and every second day for IGF-1 determination. No effects from the experimental groups were observed on the mean NEFAs or IGF-1 concentrations (p > .05). No differences between the time before male introduction and after male introduction were observed on the NEFAs concentrations (p > .05) or IGF-1 concentrations (p > .05). On the whole, only differences were observed in the NEFAs concentrations between the follicular and the luteal phases (9.48 ± 0.38 vs 8.15 ± 0.15 mg/dL for follicular and luteal phases, respectively, p < .01). The results of the present experiment demonstrated that the introduction of sexually active males at different moments of the oestrous cycle does not modify the NEFAs or the IGF-1 concentrations.Highlights Results shows that NEFAs or IGF-1 concentrations did not vary after the introduction of males. Results shows that NEFAs concentrations increases during the follicular phase. Results shows that IGF-1 concentrations did not vary during the oestrous cycle.