Semen quality, plasma testosterone, and trace element concentrations in response to dietary supplementation of an organic versus an inorganic source of zinc in Mahabadi bucks

This study was conducted to evaluate the effects of dietary supplementation of different sources of zinc on the quantitative and qualitative characteristics of semen and blood testosterone in Mahabadi mature bucks. Twenty-four mature male goats (40 ± 0.86 kg), approximately 1-1.5 years old, were divided into three groups (n = 8) and assigned to experimental treatments for 56 days in a completely randomized design. The treatments included: 1) control (a basal diet containing 22.14 mg/kg zinc without zinc supplement), 2) basal diet + 35 mg/kg Zn4 as ZnSO4 (an inorganic source of Zn), and 3) basal diet + 35 mg/kg Zn as ZnMet (an organic source of Zn). Qualitative (ejaculate volume, sperm concentration) and quantitative (viability, membrane integrity, morphology, and CASA detected parameters) properties of semen and plasma testosterone and Zn, Cu, and Fe concentrations were evaluated. Results showed that ZnMet vs. ZnSO4 increased sperm membrane integrity and plasma Zn concentration and reduced morphologically abnormal spermatozoa (P≤0.05), but there were no significant differences in other parameters. Viability, membrane integrity, morphology, some of the CASA detected parameters (total motility, straight-line velocity, average path velocity, beat cross frequency of sperm), and the plasma concentration of testosterone in zinc-supplemented groups was significantly higher than the control group. In conclusion, the positive effects of an organic source of Zn were seen in reducing abnormal spermatozoa and improving membrane integrity, plasma Zn concentration, and plasma testosterone concentration.