Dietary co-supplementation of rams with zinc, manganese and copper on freezing ability of semen

Background and Objectives: Dietary supplementation of trace minerals (zinc, copper and manganese) has positive effects on various aspects of reproductive performance of farm animals and it has a strong antioxidant effect on sperm function. Also, feeding with trace minerals affects the functional structure of sperm cells and increases the quality of sperm for cryopreservation because it may lead to cell damage, production of reactive oxygen species and reducing the antioxidant capacity of seminal plasma. The objective of this study was to investigate whether dietary supplementation of zinc, copper and manganese affected on sperm motion characteristics, percentage of viability, sperm membrane integrity after thawing, and flow cytometry tests including apoptosis, hydrogen peroxide and molecular oxygen.
Materials and Methods: Ten mature Afshari rams were all fed a nutritionally adequate diet for 70 days, from the end of September to the beginning of December. Half of the rams were randomly designated to receive dietary supplementation with a sulfate source of zinc, copper and manganese once daily for 70 days, starting 1 week after the study began. All ejaculates were diluted with a Tris-based cryoprotective extender. The extended semen was subsequently loaded into 0. 5 mL plastic straws and then they were frozen by the bio-freezer machine. One week after freezing, three straws of each ram were thawed and evaluated for sperm motion characteristics by computer-assisted-semen-analysis system, hypoosmotic swelling test and live sperm percentage. In addition, we examined hydrogen peroxide, molecular oxygen and apoptosis in frozen sperm. Proc Mixed was used for analysis of repeated measures data.
Results: Motion characteristics, percentage of sperm viability and sperm membrane integrity after thawing in the Supplemented group was relatively stable and significantly higher than in the Control group from day 28 onwards (P<0/05). At the end of this research, the levels of hydrogen peroxide, molecular oxygen, early apoptosis, late apoptosis and necrosis in the control group were significantly higher than the Supplemented group (P<0/05). The average number of live sperm in the Supplement group increased slightly at the end of the research period outside the breeding season, but it was not significant compared to the beginning of the period, but this rate at the end of the period was significantly higher than that of the Control group (P<0/05).
Conclusion: The results showed that the simultaneous supplementation of zinc, copper and manganese elements, even after the reproductive season, can have beneficial effects on the quality and freezing ability of sperm after thawing and prevent the creation of reactive oxygen species and the occurrence of apoptosis.