Effect of ß-glucan from Euglena gracilis as an antioxidant on goat semen cryopreservation

Abstract

This study aimed to determine the influence of different doses of beta-glucan on post-thaw spermatological parameters, lipid peroxidation, and total antioxidant activity of buck semen. In the non-breeding season, semen was collected from bucks twice weekly. After then, ejaculates were pooled and divided into four equal aliquots: beta-glucan concentrations of 1 mM (beta G1), 2 mM (beta G2), and 4 mM (beta G4), and a control group without antioxidants. Each sample group was diluted for cryopreservation using a dilution method involving two steps. The experimental groups were then evaluated for several parameters including sperm motility, plasma membrane functional integrity [hypoosmotic swelling test (HOST)], damaged acrosome rate [FITC-Pisum sativum agglutinin (FITC-PSA)], DNA integrity [terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL)], mitochondrial membrane potential using JC-1, evaluation of lipid peroxidation, and determination of total antioxidant activity. The post-thaw motility and plasma functional integrity of the control group were significantly lower than those values in the beta G groups (P < 0.05). Although the numerically greatest acrosome damage was detected in the control group, it was only statistically different from beta G1 and beta G4 (P<0.05). While the DNA fragmentation rate of the control group was higher than beta G4 group (P<0.05), it was similar to beta G1 and beta G2 groups (P>0.05). There was no statistical difference among all the groups regarding low mitochondrial membrane potential, MDA, and TAC rates. In line with our results, supplementation of 1mM, 2 mM and 4 mM beta-glucan to freezing extender improves the post-thaw spermatological characteristics of goat semen.