The Post Thaw Quality, Antioxidant Activity, and In vivo Fertility of Frozen-Thawed Buffalo Bull Semen Frozen-stored in the Presence of Different Concentrations of Freeze-Dried Fennel Powder

Abstract

Buffalo bull spermatozoa exhibited a higher degree of cryodamage compared to bull spermatozoa and in turn leading to reduced fertility rates following thawing. This poor freezability of buffalo bull spermatozoa can be attributed to distinct lipid composition of their plasma membrane compared to those of other species, rendering them more susceptible to damage during cryopreservation. Reproductive scientists endeavour to minimize this inevitable cryodamage through adding specific additives to the semen extender used for cryopreservation of buffalo bull spermatozoa. Fennel is a promising candidate of these additives, where the most potent antioxidants in fennel are rosmarinic, flavonoid and anethole. The present study aimed to investigate the possible effects of adding different concentrations of freeze-dried fennel powder on the post-thaw quality, enzymatic antioxidant activity, in vivo fertility of buffalo bull spermatozoa. Ejaculates were collected from seven healthy Egyptian buffalo bulls by artificial vagina twice weekly. Good-quality ejaculates were pooled and dispensed into four Aliquots; each aliquot was diluted with Tris-egg yolk citrate extender containing: 0 being as control (CTRL), 10 (FEN10, 20 (FEN20) and 30 (FEN30) µL/mL freeze-dried fennel powder, cooled, equilibrated, loaded in mini-straws before being frozen stored in liquid nitrogen at − 196°C. Frozen straws were thawed in a water bath at 37 °C for 30 s and examined for sperm motility, viability, plasma membrane integrity, acrosome integrity and DNA integrity. Seminal total protein, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) and malonaldehyde (MDA) levels were determined. The results revealed that FEN20 significantly (P < 0.05) improved the proportions of total motility, progressive motility, viability and plasma membrane integrity. Intriguingly, the control group had higher proportions of acrosomal membrane integrity and DNA integrity. There was no significant variation among the control and all treated groups in the total protein level and CAT. While SOD, GPX and MDA activity were significantly (P < 0.05) higher in FEN10. FEN10 yielded the greatest in vivo fertility rate compared to the control, FEN20, and FEN30 groups.