Reproduction in Domestic Animals最新文献

This study aimed to evaluate the effects of human chorionic gonadotropin (hCG) on the second prostaglandin F2α (PGF2α) injection in anestrous Saanen goats that had been previously exposed to a 16-h photoperiod. Seventy-two pluriparous goats were subjected to a 16-h photoperiod for 60 days. Ten days later, synchronisation of estrus was conducted with two injections of cloprostenol administered 11.5 days apart. At the second injection, goats received either 300 IU of hCG (hCG group) or no hCG (control group). Estrus response, ovarian structures, progesterone (P4) concentrations, and pregnancy rates were assessed. Estrus response after the second cloprostenol injection (70.8%; 51/72) was higher (p < 0.05) than that of the first injection (39.0%; 28/72; p < 0.05). Goats in the hCG group ovulated earlier (p < 0.05; 45.0 ± 5.9 h) compared with the control (72.9 ± 4.8 h), with a shorter interval between estrus and ovulation (-1.2 ± 7 h vs. 34.2 ± 3.3 h; p < 0.05). Although hCG increased the luteal area and P4 concentrations, pregnancy rate was drastically reduced (p = 0.05) in the hCG group (25.0% vs. 47.2%). Moreover, hCG reduced (p < 0.05) the incidence of premature luteal regression (11.1% vs. 30.6%). No differences were observed in follicular number or diameter between groups. It was concluded that even though hCG effectively induced ovulation and enhanced luteal function in goats during anestrus, its administration in conjunction with the second PGF2α injection may have excessively advanced ovulation, impairing estrus-ovulation synchrony, which markedly reduces pregnancy rate. Timings of hCG administration should be further explored to optimise its reproductive benefits without compromising pregnancy outcome.

Different routine parameters are commonly used to evaluate frozen-thawed semen quality, but no single parameter is sufficient to predict fertility accurately. The combination of multiple parameters could enhance the reliability of fertilising potential assessments in bovine semen doses; however, the simultaneous use of individual indicators becomes cumbersome and difficult to apply. This research aimed to evaluate the calculation and use of seminal quality indexes based on a set of traits from frozen-thawed semen, as a way of integrating and expressing, in a single value, the seminal quality of bulls. Ten ejaculates from five healthy and sexually mature Nelore bulls were used. The semen was frozen using a conventional nitrogen vapour protocol. Post-thawing, sperm motility and kinetics, viability and capacitation were evaluated using computerised analysis, fluorescence microscopy and flow cytometry, respectively. Sperm quality indexes (SQi) were calculated using principal component analysis (PCA). Normalisation of the SQi on a scale between 0 and 1 (N-SQi) was performed. Data were analysed using an N-way ANOVA for each dependent variable, and the means were compared between bulls using Tukey's test. Most of the parameters were positively correlated, except for the majority of the STR, LIN and NC correlations with the other variables, which were negatively correlated. The mean results for SQi and N-SQi were 1.10 ± 0.04 and 0.64 ± 0.02, respectively. There were differences in the results per bull in both MP and RAP, as well as for SQi and N-SQi. It is concluded that using seminal quality indexes is a feasible way to integrate and consolidate multiple traits from computerised analysis, fluorescence microscopy and flow cytometry of frozen-thawed semen samples into a single value to facilitate their interpretation.

Characterising body and reproductive morphometry and their association with epididymal sperm quality can contribute to the conservation of sambar deer (Rusa unicolor). Five adult males maintained in captivity at the Getúlio Vargas Zoobotanical Park (Salvador, BA, Brazil) were captured, anaesthetised, and subjected to bilateral orchiectomy as part of a population-control strategy. Body measurements included head circumference, thoracic diameter, total length, withers height, and body weight. The length, width, thickness, and weight of the testes and epididymides were measured, and the gonadosomatic index was estimated. Spermatozoa were recovered from the epididymal tail by slicing and flotation, and their morphology, membrane integrity, and kinematic parameters were assessed using a computerised computer-assisted semen analysis (CASA) system. Mean kinematic parameters were: total motility (80.61% ± 18.33%), progressive motility (54.95% ± 16.55%), average path velocity-VAP (60.58 ± 12.38 μm/s), and percentage of normal spermatozoa (77.80% ± 6.14%). Withers height showed significant positive correlations (p < 0.05) with most reproductive parameters, including testicular weight (r = 0.936), testicular volume (r = 0.936), testicular area (r = 0.878), epididymal thickness (r = 0.882), total sperm recovered (r = 0.939), progressive motility (r = 0.888), and percentage of normal spermatozoa (r = 0.968). Additionally, testicular volume, thickness, epididymal length, epididymal width, and epididymal thickness showed significant positive correlations (p < 0.05) with most of the sperm parameters studied. These findings provide important preliminary data for future investigations on the reproductive potential of this species.

Extended bull sperm for artificial insemination is routinely cryopreserved and stored in liquid nitrogen (LN₂, -196°C) tanks to maintain semen quality for extended periods. Bacterial contamination impairs sperm quality; however, hygienic conditions of LN₂ tanks are monitored insufficiently. This study aimed to assess the hygienic situation in routinely used LN₂ tanks under field conditions. For this purpose, 141 LN₂ tanks from 19 AI centres were sampled to provide an overview of bacterial contamination prevalence. Additionally, antimicrobial susceptibility tests were performed for 13 commonly used antibiotics on all bacterial species isolated from three or more LN₂ tanks. Out of 141 LN₂ tanks, 81.7% were contaminated with one (44.3%), two (26.7%), three (9.2%), or four (1.5%) bacterial species, respectively. Overall, 25 bacterial genera were found, which yielded 49 different species. Results emphasise that contamination of LN₂ tanks used in bull AI is common. Systematic monitoring and the introduction of hygiene guidelines are, therefore, recommended.

Extracellular Vesicles (EVs) are small, membrane-bound particles released by cells into biological fluids, where they function as mediators of intercellular communication. These vesicles transport a diverse array of bioactive molecules, including proteins, lipids, and nucleic acids, and play essential roles in regulating physiological and pathological processes. Recent research has revealed the significance of EVs in reproductive biology, particularly in the areas of spermatozoa maturation, oocyte development, embryo implantation, and maternal-fetal interactions. Given their widespread distribution and biological importance, EVs have been increasingly studied for their potential applications in both human and livestock reproductive medicine. Understanding the mechanisms by which EVs contribute to reproductive processes is crucial, as they offer novel opportunities for improving reproductive health, diagnosing fertility disorders, and enhancing assisted reproductive technologies. In males, EVs derived from seminal plasma and the epididymis influence sperm motility, capacitation, and fertilisation potential. In females, vesicles secreted within follicular, oviductal, and uterine fluids mediate communication between the oocyte, embryo, and maternal reproductive tract. Furthermore, placental-derived EVs regulate immune tolerance, vascular remodelling, and fetal development throughout pregnancy. EVs are emerging as promising tools for fertility assessment and reproductive diagnostics. Their molecular cargo reflects the physiological state of the reproductive system, enabling their use as non-invasive biomarkers for evaluating gamete quality, embryo viability, and pregnancy health. Despite their immense potential, challenges remain in optimising EV isolation, improving characterisation techniques, and deciphering the precise molecular mechanisms underlying their function. Standardisation of methodologies, development of targeted vesicle-based therapeutics, and validation of their efficacy in reproductive medicine are necessary to fully realise their clinical utility. The field of EV research in reproductive biology continues to evolve rapidly, and ongoing studies will undoubtedly lead to new insights into their role in fertility, embryo development, and pregnancy maintenance.

Medical approaches to reproduction control have traditionally relied on progestins, but these drugs are associated with significant adverse effects in both males and females, including an increased risk of uterine infections, mammary tumours, and metabolic complications. As a result, veterinarians often advocate for strategies such as postponing estrus in females to balance reproductive health and manage population control. In recent decades, advancements in pharmacological interventions have opened new doors. GnRH agonists, which can reversibly suppress reproductive function, have emerged as a safer and more flexible alternative to surgical sterilisation. Similarly, the use of melatonin in female cats has shown promising results in regulating estrus cycles. Other innovative solutions, such as non-surgical sterilisation techniques using immunocontraceptive vaccines, are under active development, offering hope for scalable, humane population control measures. These emerging technologies provide veterinarians with an expanding toolkit to address both clinical and ethical challenges in reproductive management.

Efficient use of stallion semen in liquid state is limited by its relatively short shelf-life. A chemically defined extender (Beyond) is now available for long-term liquid semen preservation. The objectives of the present study were to compare Beyond with milk extenders for the preservation of semen at two temperatures, and to evaluate fertility of semen cooled for 4-8 days before artificial insemination. Semen was processed using different extenders: milk, cholesterol (BotuSemen Special); milk-based (INRA 96); and Beyond. Sperm motility, membrane and acrosome integrity, and chromatin structure were evaluated in semen stored at 17°C for 7 days or at 5°C for 14 days. Sperm motility decreased in the first few days of storage regardless of extender or storage temperature. Sperm motility continued to decline at relatively constant rates in semen extended in milk extenders, but the rate of decline was substantially reduced with Beyond. Sperm motility in semen extended with Beyond was greater than in semen extended with milk extenders after 4 days of storage at 17°C, or after 7 days of storage at 5°C. Extender did not affect sperm DNA damage during storage, but sperm with intact membrane and intact acrosome were lower with Beyond. Inseminations with semen stored with Beyond at 5°C for an average of 5.5 days resulted in embryos in 61% of cycles (11/18). In conclusion, Beyond extender resulted in greater sperm motility longevity when compared to milk extenders, especially when semen was stored at 5°C. Satisfactory fertility was obtained with semen cooled for 4-8 days before artificial insemination.

The present study was undertaken to assess the effect of kisspeptin supplementation (0.0, 5.0, 10.0, 15.0, 20.0 and 40.0 μM) in cryodiluent on freezability and in vivo fertility of buffalo bull spermatozoa. Twenty-four semen ejaculates were collected using an artificial vagina from four Murrah buffalo bulls. Ejaculates having > 70% sperm motility, < 25% morphological abnormalities and > 500 million/ml concentration were diluted with Tris-egg yolk extender containing 0.0 (control), 5.0, 10.0, 15.0, 20.0 and 40.0 μM kisspeptin and cryopreserved following established protocol. The CASA-based progressive motility and viability were higher (p < 0.05) in cryodiluent containing 20.0 μM of kisspeptin in comparison to other experimental concentrations and control. Addition of kisspeptin at 20.0 and 40.0 μM in extender exhibited higher (p < 0.05) CASA-based total motility and plasma membrane integrity. Regarding CASA-based sperm kinematics, supplementation of kisspeptin (20.0 μM) in extender improved (p < 0.05) VCL and VAP as compared to other tested concentrations and control. The acrosome integrity revealed no difference (p > 0.05) in all the experimental extenders compared to control. The MDA levels were lower (p < 0.05) in cryodiluent supplemented with kisspeptin (20.0 μM) than in other concentrations and control. Sixty artificial inseminations were performed with the post-thaw semen having the most effective dose of kisspeptin (20.0 μM) and control (30 inseminations each). The conception rates were recorded to be higher (p > 0.05) using post-thaw semen containing kisspeptin (20.0 μM; 43.3%) as compared to control (33.3%). In conclusion, complementing the cryodiluent with 20.0 μM kisspeptin improved the quality and in vivo fertility of cryopreserved Murrah buffalo bull semen.

Embryonic diapause is widespread among mammals. This is the first report of successful post-thaw in vivo development of mammalian embryos cryopreserved at the diapause stage using mouse as a model species. Live offspring were obtained after cryopreservation of murine embryos and their transfer to pseudo-pregnant recipients. The sex ratio at birth was male-skewed, and the offspring were fertile. The results may open new possibilities for applying the Genome Resource Banking concept to diapausing mammalian species.