Influence of Sperm Number and Antioxidant Melatonin in Extender on the Quality of Post-Thawing Sheep Spermatozoa

This study aimed to examine the effect of spermatozoa concentration and the effectiveness of melatonin supplementation in diluent on the quality of post-thawing semen. Ejaculated semen was collected using the artificial vaginal method (MVB). The study was carried out in two stages, firstly semen was frozen in andromed diluent with different concentrations in one straw (50, 100, 200 million per straw), and the second was frozen semen in diluent supplemented with melatonin with different doses (0, 0,5, 1, 0 and 1.5 mM melatonin). Parameters observed were the movement of spermatozoa using Computer Assisted Sperm Analysis, membrane integrity, and acrosome integrity. Data were analyzed using Anova and further tested using Duncan's test. The results showed no significant difference in the quality and movement pattern of sheep semen when frozen at concentrations of 50, 100, or 200 million per straw (P 0.05). The addition of melatonin to the diluent in this study affected the total motility and progressive motility of spermatozoa at a concentration of 1.0 mM (P0.05) but did not significantly affect the percentage of spermatozoa motility pattern characteristics. From the results, it can be concluded that the concentration of per straw spermatozoa does not affect the quality of sheep semen, and melatonin supplementation in diluent can reduce the effects of the frozen-thawed process on motility, acrosome cap, and plasma membrane integrity in sheep semen. Melatonin supplementation with a concentration of 1 mM in the extender was the highest quality concentration in this study

The Addition of Antioxidant Melatonin to Extender Improves the Quality of Post-thawing Sheep Spermatozoa

Cryopreservation is an efficient technique to save sperm cells. However, cryopreservation causes biological and functional changes in sperm cells that affect the ability to fertilize. This study aimed to examine the effect of concentration on the quality of post-thawing sperm and to see the effectiveness of melatonin supplementation as an extender on the quality of post-thawing sperm. Semen collection from ejaculate was carried out once per week for two months using the artificial vaginal method. The study was carried out in 2 steps, firstly, semen was frozen in diluents with different concentrations in one straw (50, 100, 200 million per straw), and the second was frozen semen in diluents supplemented with melatonin with different doses (0, 0.5, 1.0 and 1.5 mM melatonin). The parameters observed were the movement of spermatozoa using computer-assisted sperm analysis, membrane integrity using the hypoosmotic swelling test (HOS-Test), and acrosome integrity using Trypan Blue-Giemsa staining. The results showed that the quality and movement pattern of sheep sperm did not differ when frozen at concentrations of 50, 100, or 200 million per straw. The addition of melatonin to extender in this study affected the total motility of spermatozoa at concentrations of 1.0 and 1.5 mM, while the highest progressive motility of spermatozoa was found in the 1.0 mM melatonin group. The addition of melatonin did not significantly affect the percentage of sperm motility pattern characteristics (LIN, STR, and ALH) compared to the control group. Differences in spermatozoa concentration did not affect the quality of sheep semen. Adding melatonin to extender reduces the effect of the frozen-thawed process on motility, acrosome integrity, and plasma membrane integrity in sheep sperm. Melatonin supplementation with a concentration of 1 mM in the extender before the frozen-thawed process was the highest quality concentration in this study

Global Prevalence and Potential Influencing Factors of COVID-19 Vaccination Hesitancy : A Meta-Analysis

Countries worldwide have deployed mass COVID-19 vaccination drives, but there are people who are hesitant to receive the vaccine. Studies assessing the factors associated with COVID-19 vaccination hesitancy are inconclusive. This study aimed to assess the global prevalence of COVID-19 vaccination hesitancy and determine the potential factors associated with such hesitancy. We performed an organized search for relevant articles in PubMed, Scopus, and Web of Science. Extraction of the required information was performed for each study. A single-arm meta-analysis was performed to determine the global prevalence of COVID-19 vaccination hesitancy; the potential factors related to vaccine hesitancy were analyzed using a Z-test. A total of 56 articles were included in our analysis. We found that the global prevalence of COVID-19 vaccination hesitancy was 25%. Being a woman, being a 50-year-old or younger, being single, being unemployed, living in a household with five or more individuals, having an educational attainment lower than an undergraduate degree, having a non-healthcare-related job and considering COVID-19 vaccines to be unsafe were associated with a higher risk of vaccination hesitancy. In contrast, living with children at home, maintaining physical distancing norms, having ever tested for COVID-19, and having a history of influenza vaccination in the past few years were associated with a lower risk of hesitancy to COVID-19 vaccination. Our study provides valuable information on COVID-19 vaccination hesitancy, and we recommend special interventions in the sub-populations with increased risk to reduce COVID-19 vaccine hesitancy