Effect of dietary zinc, selenium and their combination on antioxidant parameters in serum and Semen of Sanjabi mature rams

Background

Selenium and zinc play as antioxidants in biological systems, playing important roles in spermatogenesis and protecting against oxidative damage caused by oxygen radicals. This study aimed to investigate the effects of dietary intake of zinc and selenium, either separately or in combination, on antioxidant parameters in the blood and semen of ram.

Methods

Twenty mature fat-tailed Sanjabi rams, weighing 50.01 ± 5.6 kg and 20 months of age, were randomly assigned to four different treatments for a period of 120 days (from July to November). The experimental groups included: 1) the basal diet (control group, with 0.11 mg.kg⁻¹ selenium and 20.52 mg.kg⁻¹ zinc) (C), 2) the basal diet supplemented with 0.3 mg.kg⁻¹ selenium (Se), 3) the basal diet supplemented with 40 mg.kg⁻¹ zinc (Zn), and 4) the basal diet supplemented with both selenium (0.3 mg.kg⁻¹) and zinc (40 mg.kg⁻¹) (ZS). Blood samples were collected at eight-week intervals for analysis. Specifically, the levels of total antioxidant status (TAS), malondialdehyde (MDA), glutathione peroxidase (GSH-Px) and zinc (Zn) in serum, as well as GSH-Px, Zn and MDA concentrations in semen were measured.

Results

During the first two months of the experiment, the serum total antioxidant status (TAS) in all of the treated animals was significantly higher than that of the control group (P<0.01). However, after the second month, only the rams in the selenium (Se) group continued to have a significantly greater serum TAS compared to the controls until the fourth month of the experiment (P< 0.05). There was no significant difference in malondialdehyde (MDA) levels in the serum of treated animals compared to the controls at any point during the 120-day experiment (P >0.05). The serum glutathione peroxidase (GSH-Px) activity was significantly higher in the selenium (Se) group compared to the other groups (P <0.01). However, in the seminal plasma, the GSH-Px activity was found to be increased in rams supplemented with both zinc (Zn) and Se (ZS group) compared to the controls on days 60 and 120 of the experiment (P <0.05). Similarly, the dietary supplementation of selenium (Se) and zinc (Zn) resulted in a significant increase in both the seminal and blood serum zinc concentration in fat-tailed Sanjabi rams on day 120 when compared to the control group.

Conclusions

The dietary supplementation of zinc (Zn) and selenium (Se) was shown to increase the antioxidant levels in both the seminal plasma and blood serum of mature Sanjabi rams. This enhancement in antioxidant status may potentially lead to an improvement in the reproductive performance of these treated rams during the breeding season.