Effect of trace mineral injection on serum trace mineral concentrations and reproductive indicators in sheep synchronised during the anoestrus period

Sheep production represents an important source of income for farmers in Türkiye; however, reproductive inefficiencies during the anoestrus period pose a major challenge to productivity. This study aimed to evaluate the effects of injectable trace minerals (copper, selenium, manganese, and zinc) on the reproductive performance of Awassi ewes synchronised during the anoestrous period. A total of 200 clinically healthy ewes were randomly allocated to two groups: the trace mineral group (TRACE, <i>n</i> = 100), which received 2 ml of a trace mineral solution 14 days before oestrus synchronisation, and the control group (CON, <i>n</i> = 100), which received 2 ml of 0.9% NaCl. Oestrus was synchronised using intravaginal sponges containing 60 mg medroxyprogesterone acetate for 12 days, followed by administration of 500 IU equine chorionic gonadotrophin at sponge removal. Ewes were hand-mated for five days following synchronisation. Variables assessed included serum trace mineral concentrations, response to synchronisation, and reproductive outcomes (oestrus rate, pregnancy rate, lambing rate, incidence of multiple births, and dystocia). No significant differences (<i>P</i> > 0.05) were found between groups in serum concentrations of copper, zinc, or manganese. Although the duration of oestrus was significantly longer in the TRACE group compared to control (29.66 ± 0.96 h vs 26.09 ± 0.89 h; <i>P</i> = 0.006), all other reproductive indicators were similar between groups. These findings suggest that a single pre-synchronisation injection of trace minerals does not significantly improve the reproductive performance or mineral status in anoestrous Awassi ewes. Further research is needed to determine the optimal timing and dosing strategies for supplementing trace minerals in sheep.