The objective of this study was to evaluate the out-of-season reproductive performance and lamb birth weight of Kangal ewes orally administered a bolus of vitamin and mineral premix or mineral premix given as injection with at 40-45 days postpartum during the anestrous period. In total, 78 primiparous Kangal ewes with were randomly allocated to three experimental groups. Estrus induction protocol was performed and a ram was introduced to the ewes at the 80th days postpartum. Ewes in the group 1 a dose of 2 mL of injectable mineral solution at 40-45 days before oestrous synchronisation, was administered at once (n = 25). As for group 2, at 40-45 days before oestrous synchronisation, a mineral bolus was given orally once (n = 27). To the ewes in the group 3 a dose of 2 mL of physiological saline was given once to the animals (n = 26) simultaneously with group 1 and group 2. Reproductive parameters such as estrus and pregnancy rates; single, twin, triplet, and multiple pregnancy rates; litter size; embryonic mortality; fecundity; and dystocia rates were evaluated. In addition, the placentas were weighed to evaluate the effect of mineral supplements on placentation. There were no significant differences between the groups in terms of parameters above (p>0.05). However, the rate of dystocia was significantly lower in group 2 compared to Groups 1 and 3 (p<0.05). In conclusion, as a result, it was determined that slow-releasing boluses could not produce efficacy during the throughout pregnancy.