Seasonal variations in sperm acrosome reaction, osmotic tolerance and serum testosterone concentrations in rams

Potential Function of Testicular MicroRNAs in Heat-Stress-Induced Spermatogenesis Disorders

Spermatogenesis is temperature-dependent, and the increase in testicular temperature seriously affects mammalian spermatogenesis and semen quality. In this study, the testicular heat stress model of mice was made with a 43 °C water bath for 25 min, and the effects of heat stress on semen quality and spermatogenesis-related regulators were analyzed. On the 7th day after heat stress, testis weight shrank to 68.45% and sperm density dropped to 33.20%. High-throughput sequencing analysis showed that 98 microRNAs (miRNAs) and 369 mRNAs were down-regulated, while 77 miRNAs and 1424 mRNAs were up-regulated after heat stress. Through gene ontology (GO) analysis of differentially expressed genes and miRNA-mRNA co-expression networks, it was found that heat stress may be involved in the regulation of testicular atrophy and spermatogenesis disorders by affecting cell meiosis process and cell cycle. In addition, through functional enrichment analysis, co-expression regulatory network, correlation analysis and in vitro experiment, it was found that miR-143-3p may be a representative potential key regulatory factor affecting spermatogenesis under heat stress. In summary, our results enrich the understanding of miRNAs in testicular heat stress and provide a reference for the prevention and treatment of heat-stress-induced spermatogenesis disorders.

Seasonal Variations in Semen Quality, Testosterone Levels, and Scrotal Size following Dietary Flaxseed Oil and Ascorbic Acid in South African Indigenous Rams

The purpose of this study was to determine the seasonal variations in semen quality, testosterone levels, and scrotal size, following dietary flaxseed oil and ascorbic acid in South African indigenous rams. A total of 22 South African indigenous rams were randomly distributed into five treatment diets from June 2021 to May 2022 (12 months). To allow for the spermatogenesis period, semen was collected after sixty days of dietary supplementation with treatment diets. Blood was collected twice a week using an 18-gauge needle and vacutainer tubes and sent to the laboratory for testosterone analysis. Semen and blood collection were repeated eight times each season. The scrotal size (circumference, length, and width) was measured using a flexible measuring tape. Data was subjected to the General Linear Model (GLM) in Minitab® 2017. Treatment means were separated using Fisher’s t-test and considered significantly different when the p-value was less than 0.05. Seasons and diet had an effect on progression, total motility, and testosterone levels. For instance, NC during the spring season had the lowest progressive motility (42.84 ± 5.32), followed by the summer (49.38 ± 4.49), winter (62.46 ± 4.35), and autumn (63.26 ± 3.58). Notably, when treatment diets were introduced, improvements were realized, and there were significant differences (p < 0.05) among the seasons following supplementation of FLAX, ASCA, and FLAX + ASCA, except for FLAX in the autumn season (53.83 ± 4.16). Total motility did not differ significantly (p > 0.05) between the seasons when the NC and PC diets were supplemented; nevertheless, there was an improvement when FLAX, ASCA, and FLAX + ASCA were supplemented. Testosterone levels were significantly influenced by the seasons when negative and PC diets were supplemented. It is noteworthy that supplementing FLAX + ASCA can reverse the influence of the season on the testosterone levels (spring, 27.52 ± 4.42; summer, 20.23 ± 5.11; autumn, 25.24 ± 3.96; and winter, 25.92 ± 4.42). In conclusion, seasons do affect semen quality and testosterone levels of South African indigenous rams. However, flaxseed oil and ascorbic acid can reverse the seasonal variations in semen quality and testosterone levels.

Metabolomic profiling of Dezhou donkey seminal plasma related to freezability

Donkeys are indispensable livestock in China because they have transport function and medicinal value. With the popularization of artificial insemination on donkeys, semen cryopreservation technology has gradually become a research hotspot. Seminal plasma is a necessary medium for transporting sperm and provides energy and nutrition for sperm. Seminal plasma metabolites play an important role in the process of sperm freezing, and also have an important impact on sperm motility and fertilization rate after freezing and thawing. In this study, liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis was used to compare the metabolic characteristics of seminal plasma of high freezability (HF) and low freezability (LF) male donkeys. We identified 672 metabolites from donkey seminal plasma, of which 33 metabolites were significantly different between the two groups. Metabolites were identified and categorized according to their major chemical classes, including homogeneous non-metal compounds, nucleosides, nucleotides, and analogues, organosulphur compounds, phenylpropanoids and polyketide, organoheterocyclic compounds, organic oxygen compounds, benzenoids, organic acids and derivatives, lipids and lipid-like molecules, organooxygen compounds, alkaloids and derivatives, organic nitrogen compounds. The results showed that the contents of phosphatidylcholine, piceatannol and enkephalin in donkey semen of HF group were significantly higher than those of LF group (p < .05), while the contents of taurocholic and lysophosphatidic acid were significantly lower than those of LF group (p < .05). The different metabolites were mainly related to sperm biological pathway response and oxidative stress. These metabolites may be considered as candidate biomarkers for different fertility in jacks.

Organic Zn and Cu interaction impact on sexual behaviour, semen characteristics, hormones and spermatozoal gene expression in bucks (Capra hircus)

The reproductive performance during the transition from prepubertal to pubertal stage was evaluated in Osmanabadi breed bucks supplemented with organic Zinc (Zn) and Copper (Cu). A total number of 40 bucks aged 20 weeks were randomly assigned to 10 groups (each n = 4). The control group was maintained with basal diet, without any additional mineral supplementation. The treatment groups were supplemented with graded doses of organic Zn (Zn 20 mg, Zn 40 mg and Zn 60 mg), Cu (Cu 12.5 mg, Cu 25 mg and Cu 37.5 mg) and a combination of Zn + Cu (Zn 20 mg + Cu 12.5 mg, Zn 40 mg + Cu 25 mg and Zn 60 mg + Cu 37.5 mg), respectively for a period of 26 weeks (up to the age of 46 weeks). Sexual behaviour and scrotal biometry were recorded periodically. Blood and semen samples were collected and processed for LH estimation in blood plasma, and testosterone, T3 and T4 hormones in the seminal plasma. The mounts with ejaculation were observed earlier (P < 0.05) in the treatment bucks (from 38th week of age) than the control group (43rd week onwards). A positive correlation was observed between blood plasma LH and testosterone with total mounts (r = 0.31, P < 0.05; r = 0.51, P < 0.01) and mounts without ejaculation (r = 0.40, P < 0.01; r = 0.52, P < 0.01). A negative correlation between T4 with sperm number per ejaculation (r = -0.31, P < 0.05) and sperm concentration (r = -0.35, P < 0.05) had been noticed. Different doses of minerals showed positive interaction (P < 0.05) with sperm functional and behavioural characteristics. The spermatozoal gene expression of ODF2 and ZCCHC6 were significantly influenced by the mineral supplementation in all doses. The ZCCHC6 gene expression was positively correlated with testosterone (r = 0.50, P < 0.001) and sperm number per ejaculation (r = 0.42, P < 0.001), and ODF2 gene with T3 hormone (r = 0.34, P < 0.05). The present study indicates that the diet supplemented with organic trace minerals cause intense sexual behaviour, enhancement in sperm number per ejaculate, total motility, spermatozoal genes expression and altered LH, testosterone and T4 hormones.