Parenteral supplementation of Cu, Zn and Mn enhances boars' sperm quality.

INTRODUCTION

The trace elements concentrations of blood might play a key role in the trace element concentration of seminal plasma, as well as in the improvement of semen volume and sperm morphology in boars.

OBJECTIVE

To assess the effect of supplementation of Cu, Zn and Mn on their concentrations in blood serum and seminal plasma and sperm quality in boars.

METHODS

Eighteen boars of the Duroc Jersey breed were selected and their blood and semen (54 ejaculates before supplementation) were extracted. Coinciding with the third sampling and after of blood taken, the boars were supplemented subcutaneously with 37.5 mg of Cu, 75 mg of Zn and 37.5 mg of Mn; 40 days after the supplementation the fourth sampling was taken. Cu and Zn concentrations in blood serum and seminal plasma were determined by atomic absorption spectrophotometry, while the sperm pathologies were determined by microscopy and the concentrations of Cu and Zn in blood serum and seminal plasma, and semen pathologies were compared using the t-Student test for paired samples. A simple linear correlation was made between the minerals concentration in seminal plasma with the percentage of spermatozoa with abnormal forms.

RESULTS

Although the concentrations of Zn in blood serum did not show differences between sampling periods (P < 0.05), they were significantly higher (P < 0.01) in the seminal plasma after supplementation as compared to its levels before supplementation. In addition, the concentrations of Cu and Zn in seminal plasma were increased (P < 0.01), and the total spermatic pathologies were reduced; especially those of the head, neck and intermediate part of the tail (P < 0.001). Besides, macrocephaly, double head and broken acrosome were the most common pathologies (P < 0.05). Moreover, parenteral supplementation of Cu, Zn and Mn was a protective factor to the presentation of ejaculates with abnormal sperm percentages higher than 10% (χ = 6.1544; P = 0.0131). The prevalence of abnormal shapes of boars' sperm before supplementation was 0.40; after supplementation the answer was 0.05 and the prevalence ratio was 0.13 with a confidence interval of 95% from 0.01 to 0.94. Moreover, Zn concentrations in blood serum were not correlated with those of the seminal plasma (P > 0.05, r = - 0.0353); however, the concentrations of Cu in both fluids were correlated (P < 0.05, r = 0.2254). In addition, the Zn values in the seminal plasma and the percentage of abnormal spermatozoa had a negative and highly significant correlation (P < 0.0001, r = - 0.5628). However, the Cu concentrations in the semen were not significantly correlated with the abnormal sperm forms (P > 0.05, r = 0.0200).

CONCLUSION

From the present study it can be concluded that in boars fed with diets that meeting their requirements in trace minerals according to NRC (2012) [1], parenteral supplementation of 37.5 mg of Cu, 75 mg of Zn and 37.5 mg of Mn increased the Zn concentrations in the seminal plasma and reduced the sperm pathologies, which resulted in an increase of the boars' sperm quality.