Study on cryopreservation of Guanzhong dairy goat semen with bovine semen seminal plasma

Effects of organic and inorganic selenium supplementation on frozen-thawed ram semen at two cooling periods

The aim of this study was to evaluate the effects of different selenium compounds on the sperm quality of cryopreserved ram semen. Ejaculates from four rams, collected using an artificial vagina heated to 38 °C, were individually evaluated. The approved ejaculates were pooled and diluted (1:1 v:v) in Tris-egg yolk extender (20%, v/v) and separated into two control groups, one cooled for 2 h and the other for 4 h. The pooled ejaculates at the two cooling periods were supplemented with two doses (0.5 and 1 μg/mL) of organic selenium (ORG), and inorganic selenium (SeNa), each. The samples were packed in 0.25 ml straws, at a concentration of 400 × 106 sperms/mL and stored in liquid nitrogen. The straws were thawed in a water bath at 37 °C for 20 s, and the samples were subjected to sperm kinetics evaluation by Computer Assisted Semen Analysis software. Sperm membrane integrity, acrosome morphology, and mitochondrial potential were assessed. In addition, oxidative stress markers reactive oxygen species (ROS), ferric reducing antioxidant power (FRAP), thiobarbituric acid reactive species (TBARS), and glutathione peroxidase (GPx) enzyme activity) were also evaluated. No significant improvement was observed in the ram semen quality at the two cooling times. Supplementation of the freezing extender with 0.5 μg/mL ORG, subjected to 4 h cooling period, increased the sperm motility when compared with the control group at the same cooling time. In addition, the 0.5 μg/mL SeNa group, under the 2 h cooling period, showed an increase in sperm motility when compared to the control group at the same cooling period. Considering the importance of sperm motility as a fertility parameter, our study indicates that supplementation with ORG and SeNa can help improve the total motility of the cryopreserved ram semen.

Quercetin in semen extender improves frozen-thawed spermatozoa quality and in-vivo fertility in crossbred Kamori goats

This study investigated the antioxidant effect of quercetin-treated semen on frozen-thawed spermatozoa quality and in-vivo fertility in crossbred Kamori goats. In total, 32 ejaculates from four fertile bucks were diluted in Tris-based egg yolk extender with varying levels of quercetin (0, 1, 5, 10, and 15 μM). Qualified semen samples were pooled and frozen in French straws. The results revealed that the addition of quercetin in the semen extender increased (p < 0.05) frozen-thawed sperm total motility (TM), progressive motility (PM), rapid velocity (RV), average path velocity (VAP), straight line velocity (VSL), curvilinear velocity (VCL), and amplitude of lateral head (ALH) displacement in contrast to the control group. Quercetin supplementation had no effect on beat cross frequency (BCF), straightness (STR), and linearity (LIN) (p > 0.05). Quercetin showed significantly higher (p < 0.05) plasma membrane and acrosome integrity and viability (p < 0.05) of spermatozoa in contrast to the control group. Quercetin in the semen extender significantly increased (p < 0.05) superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), ascorbate peroxidase (APX), and total antioxidant capacity (TAC) levels while reduced (p < 0.05) the contents of total oxidant status (TOS) and malondialdehyde (MDA), which were in contrast to the control group. Ultrasound results revealed that 24 out of 30 (80%) goats were found pregnant when semen was treated with 5 μM quercetin while the control group showed 18 out of 30 (60%) animals were pregnant. Thus, the study concluded that 5 μM quercetin-treated semen was found to be efficient, showed increased antioxidant status, and reduced oxidant production, leading to improved spermatozoa quality and in-vivo fertility in goats.

An Overview on Assay Methods to Quantify ROS and Enzymatic Antioxidants in Erythrocytes and Spermatozoa of Small Domestic Ruminants

The present review aims to provide an overview of the assay methods for the quantification of ROS and principal enzymatic antioxidants as biomarkers of oxidative stress in erythrocytes and spermatozoa of small domestic ruminants. A complete literature search was carried out in PubMed, Scopus and the World Wide Web using relevant keywords and focusing on the last five years (2018-2023). Among spectrophotometry, fluorometry and chemiluminescence, the most widely used method for ROS assay is fluorometry, probably because it allows to simultaneously assay several ROS, using different probes, with greater economic advantages. Regarding intracellular antioxidant enzymes, recent literature reports only spectrophotometric methods, many of which use commercial kits. The use of a less sensitive but cheapest method is suitable because both erythrocytes and spermatozoa samples are highly concentrated in domestic ruminant species. All methods considered in this review have been found to be appropriate; in general, the differences are related to their costs and sensitivity. Quantification of ROS and enzymatic antioxidant activity in erythrocytes and spermatozoa may find application in the study of the welfare and health status of small domestic ruminants for monitoring livestock production.

Plasma membrane lipid composition and metabolomics analysis of Yorkshire boar sperms with high and low resistance to cryopreservation

The resistance of sperm to freezing varies widely among boars. The semen ejaculate of different boars can be grouped into poor freezability ejaculate (PFE) and good freezability ejaculate (GFE). In this study, five Yorkshire boars each of the GFE and PFE were selected by comparing the changes in sperm motility before and after cryopreservation. Firstly, we found that the sperm plasma membrane of the PFE group showed weak integrity after PI and 6-CFDA staining. Then the electron microscopy results verified that the plasma membrane condition of all segments of GFE was better than that of PFE segments. Furthermore, the lipid composition of sperm plasma membranes in GPE and PFE sperm was analyzed by using mass spectrometry, and 15 lipids showed differences between the two groups. Among those lipids, only phosphatidylcholine (PC) (14:0/20:4) and phosphatidylethanolamine (PE) (14:0/20:4) were higher in PFE. The remaining lipid contents, including those of dihydroceramide (18:0/18:0), four hexosylceramides (18:1/20:1, 18:0/22:1, 18:1/16:0, 18:1/18:0), lactosylceramide (18:1/16:0), two hemolyzed phosphatidylethanolamines (18:2, 20:2), five phosphatidylcholines (16:1/18:2, 18:2/16:1, 14:0/20:4, 16:0/18:3, 18:1/20:2), and two phosphatidylethanolamines (14:0/20:4, 18:1/18:3), were all positively correlated with resistance to cryopreservation (p < 0.05, r > 0.6). Moreover, we analyzed the metabolic profile of sperm using untarget metabolomic. KEGG annotation analysis revealed that the altered metabolites were mainly involved in fatty acid biosynthesis. Finally, we determined that the contents of oleic acid, oleamideetc, N8-acetylspermidine etc., were different between GFE and PFE sperm. In summary, the different lipid metabolism levels and long-chain polyunsaturated fatty acids (PUFAs) in plasma membrane may be key factors contributing to differences in sperm resistance to cryopreservation among boars.