Age and other factors like season and breed are often associated with sperm quality and fertility in domestic animals. Even though many studies assessed the relationship between the age of the male and sperm parameters, the effects have not been comprehensively evaluated. Changes in semen quality from pubertal (young) to adult and old age were identified in the bull, ram, buck, boar, dog, and stallion, respectively. The review discusses the association between male age and semen volume, the total number of spermatozoa per ejaculate, sperm concentration, motility, morphology, sperm cell function, sperm DNA integrity, oxidative stress, and antioxidant activity in these species of animals. Generally, semen characteristics improve to a certain age, which declines as the animal ages. Only a few studies evaluated the impact of advanced age or employed advanced functional sperm assessment methods to assess age-related changes in sperm quality and male fertility. Such studies in the dog or stallion, for instance, may contribute to advancing knowledge in human-assisted reproductive techniques used in patients of advanced paternal and maternal age.

The COVID-19 pandemic has resulted in millions of human deaths, prompting the rapid development and regulatory approval of several vaccines. Although Nigeria implemented a COVID-19 vaccination program on 15 March 2021, low vaccine acceptance remains a major challenge. To provide insight on factors associated with COVID-19 vaccine hesitancy (VH), we conducted a national survey among healthcare workers, academics, and tertiary students, between 1 September 2021 and 31 December 2021. We fitted a logistic regression model to the data and examined factors associated with VH to support targeted health awareness campaigns to address public concerns and improve vaccination rates on par with global efforts. A total of 1525 respondents took part in the survey, composed of healthcare-workers (24.5%, 373/1525), academics (26.9%, 410/1525), and students (48.7%, 742/1525). Only 29% (446/1525) of the respondents were vaccinated at the time of this study. Of the 446 vaccinated respondents, 35.7% (159/446), 61.4% (274/446) and 2.9% (13/446) had one, two and three or more doses, respectively. Reasons for VH included: difficulty in the vaccination request/registration protocols (21.3%, 633/1079); bad feelings towards the vaccines due to negative social media reports/rumours (21.3%, 633/1079); personal ideology/religious beliefs against vaccination (16.7%, 495/1079); and poor confidence that preventive measures were enough to protect against COVID-19 (11%, 323/1079). Some health concerns that deterred unvaccinated respondents were: innate immunity issues (27.7%, 345/1079); allergic reaction concerns (24.6%, 307/1079); and blood clot problems in women (21.4%, 266/1079). In the multivariable model, location of respondents/geopolitical zones, level of education, testing for COVID-19, occupation/job description and religion were significantly associated with VH. Findings from this study underscore the need for targeted awareness creation to increase COVID-19 vaccination coverage in Nigeria and elsewhere. Besides professionals, similar studies are recommended in the general population to develop appropriate public health interventions to improve COVID-19 vaccine uptake.

Accurately predicting male fertility is crucial for the animal breeding industry due to its significant economic implications. Existing literature suggests that mammalian fertility is partially dependent on sperm DNA integrity. However, routine semen analysis often fails to detect DNA damage and does not consistently correlate with field fertility outcomes. While assessing sperm DNA integrity provides valuable biological insights, its role in diagnosing animal infertility remains uncertain. This meta-analysis evaluated the association between sperm DNA fragmentation (SDF) and fertility in farm animals. Comprehensive searches were conducted using PubMed, Google Scholar, and Springer Link Library, with results stratified by animal species and SDF detection methods. Across 30 studies, the overall correlation coefficient (COR) between SDF and male fertility was -0.46 (95% confidence interval [CI]: -0.54 to -0.37; Z = -8.97; p < 0.001). A significant association was observed in bulls (COR = -0.47; 95% CI: -0.54 to -0.40; Z = -11.13; p < 0.001) and stallions (COR = -0.54; 95% CI: -0.72 to -0.29; Z = -3.83; p < 0.001), whereas no significant relationship was found in boars (COR = -0.19; 95% CI: -0.37 to 0.01; Z = -1.84; p = 0.07). The effect of SDF on male fertility was analyzed in 15 studies, demonstrating significantly higher SDF values in low-fertility animals compared to high-fertility groups (SMD = 0.85; 95% CI: 0.68 to 1.01; Z = 10.07; p < 0.001). This pattern was observed in both bulls (SMD = 1.21; 95% CI: 0.85 to 1.57; Z = 6.59; p < 0.001) and stallions (SMD = 0.64; 95% CI: 0.44 to 0.85; Z = 6.14; p < 0.001) subgroups. These findings suggest that incorporating SDF assays into breeding soundness evaluations could enhance the accuracy of selecting high-quality breeding males for artificial breeding programs. However, further research with adequately powered studies, standardized methodologies, and appropriate sample sizes is necessary to fully elucidate the impact of elevated SDF on fertility in farm animals.

In some African and Asian countries, Azadirachta indica (AI) has been fed to livestock for decades and traditionally used to treat certain animal and human diseases. Recently, there are suspicions that the plant may possess anti-reproductive properties and concerns that the continued use of AI as forage or for folkloric medicine may detrimentally affect reproduction in the subjects. To address these challenges, this work determined the reproductive and fertility effects of a methanolic seed extract of AI (MSEAI) using adult female albino rats (AFARs) as an experimental model. Sixty-four AFARs were randomly assigned into four groups (A–D) of sixteen rats each. Group A was the control while groups B, C and D were treated daily with 50, 100 and 200 mg/kg of MSEAI respectively, for 28 consecutive days via oral gavage. Blood samples were collected for hormonal and biochemistry assays. Ovarian samples from the experimental rats were harvested for histopathological studies. Thereafter, the remaining experimental rats were bred, and certain fertility indices determined. The mean serum FSH and LH levels were significantly decreased (p ≤ 0.05) in the 100 and 200 mg/kg groups. The histopathological studies revealed massive follicular degeneration in the 100 and 200 mg/kg treatment groups. The fertility indices indicated that the post-implantation survival index was 100% in the control and 0% in the 200 mg/kg treatment group. No abortion occurred in the control and 50 mg/kg groups, but 25% and 100% of the pregnant does aborted in the 100 and 200 mg/kg treatment groups, respectively. Considering that high doses (100 mg/kg and 200 mg/kg) of MSEAI had significant anti-reproductive and antifertility properties, the use of AI as forage or for ethnoveterinary medicine in breeding females may adversely affect their reproductive potentials. However, the anti-reproductive and antifertility effects could be utilized in rodent depopulation programs in animal agriculture and as a contraceptive to limit the proliferation of stray dogs, known to be reservoirs of the rabies virus in developing countries. Moreover, the MSEAI could be further refined for human use as an effective, cheap, eco-friendly and acceptable alternative to synthetic/modern contraceptives, the use of which is limited in developing nations due to superstitious beliefs and their multiple side effects.

This study aimed to assess differences in fresh semen quality between mature and senile dogs, focusing on oxidative stress markers, including spermatozoa lipid peroxidation and enzymatic antioxidant activity. Furthermore, the ability of frozen-thawed spermatozoa from these age groups to bind to the zona pellucida was investigated. Forty clinically healthy dogs were categorized into two groups: mature (3 ± 0.2 years; n = 20) and senile (10 ± 0.2 years; n = 20). A total of 107 semen samples (2–3 ejaculates per dog) were analyzed for motilities and kinetic parameters, sperm concentration, total sperm count (TSC), acrosome and membrane integrity, morphological defects, DNA fragmentation, lipid peroxidation, and the enzymatic activities of superoxide dismutase, catalase, and glutathione peroxidase in spermatozoa and seminal plasma. A zona-binding assay was performed using frozen-thawed semen from mature (n = 10) and senile (n = 10) dogs. Mature dogs exhibited significantly higher total motility, sperm concentration, TSC, membrane integrity, and zona binding capacity compared to senile dogs (P < 0.05). Conversely, senile dogs had significantly higher proportions of proximal cytoplasmic droplets and tail defects (P < 0.05). However, lipid peroxidation, enzymatic antioxidant activities, and acrosome integrity did not differ significantly between the groups (P > 0.05). In conclusion, the observed decline in fresh semen quality with age in dogs does not appear to be associated with increased susceptibility to oxidative stress. Furthermore, frozen-thawed spermatozoa from mature dogs exhibited superior zona binding capacity, likely due to a greater proportion of progressively motile sperm.