Zinc supplementation improves semen quality in boars

Abstract

One of the causes of infertility in boars is nutritional deficiency. Interestingly, zinc has been used for improving semen quality in boars. Thus, the objective of this study was to investigate the effect of zinc as feed supplementation in order to improve semen quality in infertile boars. Three purebred Pietrain boars with a poor semen quality history were selected for the experiment. The semen samples were collected once a week for 4 weeks before the treatment period and the semen evaluated immediately. Fifteen grams (a total concentration of 150 ppm) of zinc were supplemented daily in the normal feed. The testing period was 16 consecutive weeks. The semen samples were evaluated for volume, concentration, motility (by computer-assisted sperm assay), sperm viability (by SYBR-green staining), acrosome integrity (by FITC-PNA staining), mitochondrial activity (by JC-1 staining) and sperm morphology (by Giemsa’s staining for sperm head and formal saline fixation for sperm tail). The semen samples were also preserved in commercial semen extender and stored at 16 °C for three days after ejaculation. The results showed that zinc supplementation significantly improved acrosome integrity (40.38 ± 7.13% and 70.56 ± 21.36%, respectively) and sperm viability (66.38 ± 5.46% and 79.66 ± 4.11%, respectively) at the ejaculation date and also significantly enhanced acrosome integrity after three days preservation (27.84 ± 7.78% and 67.36 ± 22.43%, respectively). In addition, we also found an increasing trend in acrosome integrity, sperm viability and progressive motility after 4 to 8 weeks of zinc supplementation. This study revealed that daily zinc addition can improve semen quality in infertile boars and can be used on farms to improve semen quality.