Reproduction in Domestic Animals最新文献

The influence of dead sperm on their healthy counterparts in bovine semen is not well established. This is particularly relevant to artificial insemination (AI), since semen handling and biotechnological procedures can increase the percentage of dead sperm. This study aimed to evaluate the impact of acrosome-disrupted (sonicated) spermatozoa on the quality of neighbouring untreated viable cells after cryopreservation. Semen samples from 12 healthy Holstein bulls were diluted (80 × 10⁶ sperm/mL) in pre-warmed OptiXcell extender at 38°C. A 6 mL portion of diluted semen underwent sonication, and both sonicated and untreated semen samples were mixed to produce treatment groups (TG) as: TG25%, TG50% and TG75% sonicated sperm. Control (CTRL) was not mixed with sonicated sperm. Progressive sperm motility was assessed during a thermo-resistance test after 30 (on-test) and 120 min (off-test) of incubation at 38°C. Results of delta and relative variation of progressive sperm motility showed a significant decline in the TG75% compared to the CTRL (p = 0.013 and 0.034, respectively). Flow cytometry revealed a gradual decline in percentage of viable acrosome-intact sperm with low membrane fluidity and low intracellular calcium (p < 0.001). A comparable decrease was observed for percentage of viable acrosome-intact sperm with high mitochondrial membrane potential (p < 0.001). Considering these findings, this study suggests that post-sonication leakage of acrosomal/cellular content could compromise the functionality of untreated spermatozoa, highlighting the necessity to conduct further mechanistic investigation to evaluate possible damaging pathways.

The objective of this study was to evaluate the effect of insemination timing with sex-sorted semen on fertility in dairy cows subjected to a timed artificial insemination (TAI) protocol. A total of 611 Holstein cows (46 ± 3 DIM) were enrolled and subjected to a presynchronized Ovsynch protocol (G7G; PGF₂α-2d-GnRH-7d-GnRH-7d-PGF₂α-56 h-GnRH), and randomly allocated to four treatment groups. The control group (CONV-14, n = 154) was inseminated with conventional semen 14 h after the final GnRH, while cows in the sex-sorted semen groups were inseminated at 14 (SS-14, n = 152), 18 (SS-18, n = 153), or 22 h (SS-22, n = 152) after the same treatment. The same bull was used for all inseminations. All cows were examined by ultrasonography to individually evaluate ovarian responses to the protocol and pregnancy status. No significant differences were observed among groups in body condition score, milk yield, cyclicity at the beginning of the protocol, response to the protocol, or follicle size at TAI. Pregnancies per artificial insemination were similar with 50.0% (77/154) in the CONV-14 group, 42.8% (65/152), 48.4% (74/153), and 43.4% (66/152) in the SS-14, SS-18, and SS-22 groups, respectively. No significant difference was observed in embryonic loss rates among groups: 5.2% in CONV-14, 9.2% in SS-14, 4.1% in SS-18, and 13.6% in SS-22, while SS-22 was numerically higher (~7%) than the average of the other SS groups. Overall, conception rates were higher in cows responding to the first GnRH than in non-responders (49.7% vs. 32.3%, p < 0.0005), with a significant difference observed only in the CONV-14 and SS-18 groups (p < 0.005). Estrous expression during TAI was associated with higher conception rates in the CONV-14 group (75.0% vs. 45.4%, p = 0.008), while no such difference was detected in the combined SS groups (51.8% vs. 43.3%). However, the conception rate in the SS-22 group (36.7%) was distinctly lower (p < 0.02) than in other SS groups (53.6% in SS-14, 68.0% in SS-18). In conclusion, contrary to the expectation that advancing insemination closer to ovulation with sex-sorted semen would be advantageous, fixed time insemination at 22 h within the TAI program showed poorer outcomes compared to 18 h, which achieved a relative conception rate of 97% compared with conventional semen. It was also concluded that TAI at 22 h should not be recommended in cows exhibiting estrus on the day of insemination.

The main objective of this study was to assess the effects of donor age on the development of in vitro-derived sheep embryos. Ovaries were obtained after slaughter from cycling Polish Longwool ewes aged 1.5-3 years (Group Y-'young'; n = 14) or 8-9 years (Group O-'old'; n = 16). Cumulus-oocyte complexes were collected and subjected to in vitro maturation (IVM), followed by in vitro fertilisation (IVF) with fresh capacitated ram semen. The resultant embryos were then cultured and monitored with a time-lapse (TL) imaging system for up to 8 days (Group Y, n = 64 and Group O, n = 48). The timing of key developmental stages relative to the moment when the oocytes and sperm were combined and including cleavage divisions as well as morula and blastocyst formation was recorded. Both the cleavage (68.75%) and blastocyst formation (26.6%) rates were significantly higher in younger ewes compared with their older counterparts (50.0% and 10.4%, respectively), with Group Y zygotes showing fewer (p < 0.05) incidences of abnormal cleavage and morphology (fragmentation, direct cleavage or asymmetrical cleavage) compared with Group O (10.9% vs. 33.3%, respectively). The first cleavage division occurred earlier (25:42 ± 3:43 vs. 29:20 ± 6:59 [hours: minutes post-insemination]; mean ± SD; p < 0.05) and the duration of the second cell cycle (time between the first and second mitotic division) was greater for Group Y compared with Group O (11:20 ± 9:51 vs. 4:14 ± 6:40; p < 0.05). No significant differences were observed between the times of the following mitotic divisions or formation of morulae and blastocysts. This study documents the specific differences in embryo morphokinetics between donor ewes varying in age and highlights the usefulness of TL imaging for assessing the influence of maternal ageing on embryogenesis in sheep as a model for different mammalian species including humans.

The present study investigated the relationship between seminal parameters and bull conception rate (BCR) in 72 Murrah bulls using Computer-Assisted Sperm Analysis (CASA). The BCR was calculated by obtaining data of artificial insemination spanned over two decades from buffalo farms of two organised herds of India. The association of seminal parameters and BCR was studied using multiple regression and principal component analysis. The average BCR was 38.95% ± 1.51%, ranging from 22.50% to 80.51%. Total motility (TM), progressive motility (PM), average path velocity (VAP), straight line velocity (VSL), curvilinear velocity (VCL), and amplitude of lateral head displacement (ALH) showed significant positive correlations with BCR, whereas straightness (STR) and linearity (LIN) were negatively correlated. Multiple regression (R² = 0.29) identified TM as the most reliable predictor of BCR. Principal component analysis (PCA) extracted three components, PC1 (Sperm velocity and head movement, 54.36% variance), PC2 (Trajectory and beat frequency, 19.56%), and PC3 (Progressive motility and path accuracy, 12.98%), explaining 86.90% of the total variance. Regression using PC scores (R² = 0.24) indicated positive effects of PC1 and PC3, and a negative effect of PC2 on fertility. Overall, sperm velocity and progressive motility were primary fertility determinants, while excessive linearity hindered conception success. Therefore, association of seminal parameters with BCR can be explored for enhancing breeding efficiency of bulls. Future breeding programmes should prioritise sperm velocity and progressive motility traits while avoiding excessive linearity to improve bull fertility and conception success.

The objective of the study was to investigate the vanillic acid's (VA) protective effects, a phenolic compound, on the ram semen after freeze-thaw. Semen was obtained from Ramlıç rams and was diluted with control (0 μg/mL VA) and VA-supplemented Tris-based extenders at concentrations of 1, 10 and 50 μg/mL. The diluted semen was equilibrated for 2 h at +4°C, filled into 0.25 mL straws and frozen in liquid nitrogen vapour. It was then stored in a liquid nitrogen container at -196°C. For analysis, the samples were thawed at 37°C for 30 s in a water bath. There was no difference detected among total and progressive motility as well as velocity parameters (p > 0.05) except for rapid progressive motility (p < 0.05). The findings support the idea that VA has an outstanding effect on reducing DNA damage (p < 0.001). While there was no positive development with regard to total oxidant status (p > 0.05), VA enhanced the antioxidant defences of total antioxidant status (p < 0.05). VA administered at doses of 10 and 50 μg increased total antioxidant status (p < 0.01). Lipid peroxidation was not directly affected by VA application (p > 0.05); otherwise, 10 and 50 μg VA treatments showed a positive effect on viability (p < 0.001). Based on findings, it was concluded that although VA was put in the semen extender, it did not have an ameliorative potency on sperm motility and velocity properties except for specific sub-parameters such as rapid progressive motility. All applied doses reduced DNA damage, and 10 and 50 μg doses supported cellular viability.

In vitro maturation (IVM) is a crucial step in the in vitro embryo production (IVEP) of bovine oocytes, requiring coordinated nuclear and cytoplasmic changes for proper embryonic development. However, oocyte quality is often compromised by oxidative stress (OS), primarily caused by reactive oxygen species (ROS) generated under in vitro conditions. Natural antioxidants have been suggested as a solution for OS by neutralising ROS and restoring cellular homeostasis. Over the past few decades, growing research efforts have been directed toward incorporating antioxidants into culture media to enhance oocyte maturation and, consequently, improve the subsequent developmental potential of embryos. Recent studies highlight the roles of enzymatic antioxidants (e.g., superoxide dismutase, catalase) and non-enzymatic antioxidants (e.g., vitamins C and E) in enhancing embryonic development. Strategic combinations of antioxidants have shown promise in optimising embryo quality by mitigating oxidative stress and enhancing developmental outcomes. Here, we aim to recapitulate recent advances in knowledge regarding the effects of antioxidants on bovine oocyte quality and developmental potential during IVM, and subsequent embryo development, and to discuss their importance in the context of enhancing reproductive success.

The TGF-β/Smad signalling pathway plays a critical regulatory role in mammalian follicular development. Vascular Cell Adhesion Molecule 1 (VCAM1), as a member of the immunoglobulin (Ig) superfamily, is commonly expressed in various cells of the mammalian ovary and affects ovarian development. Previous studies have shown that TGF-β1 is a regulator that down-regulates the expression of VCAM1 in human granulosa cells, but its specific mechanism remains unclear. In this study, we revealed that in porcine follicular granulosa cells, TGF-β1 reduces VCAM1 expression by activating TGF-β receptor type I and through the Smad pathway. This down-regulation can be completely reversed by knockdown of Smad2, but not Smad3, suggesting that Smad2 may exert a non-redundant, specialised function in the regulation of VCAM1 by the TGF-β/Smad signalling pathway. These results enhance the understanding of the regulatory mechanisms of the TGF-β signalling pathway in reproduction and provide a theoretical basis for the regulation of reproductive traits.

Reproductive efficiency in boars partly depends on semen quality. However, it is challenging to predict sperm fertility once acceptable quality endpoints have been met. This study aims to establish a link between different semen quality parameters and farm fertility outcomes in semen doses selected for commercial use. We analysed 105 ejaculates from 15 adult Pietrain boars, extended into 45 mL artificial insemination (AI) doses. A total of 605 sows were inseminated (40.1 ± 7.8 females/boar) and fertility, farrowing rate and prolificacy data were recorded. Sperm evaluation included sperm plasma analysis, kinematics, morphology, viability, acrosome integrity, apoptotic-like changes, mitochondrial activity and DNA damage (DNA fragmentation poly-ADP ribose polymerase 1, PARP1, together with its product PAR and its cleaved form cPARP). The sperm membrane and acrosome were evaluated using the short hypo-osmotic swelling test (sHOST) and the osmotic resistance test (ORT). Fertility and farrowing rates exceeded 94%, with an average of 20.18 ± 2.03 piglets born/litter (average born alive: 87.75% ± 5.61%). Negative correlations were found between damaged acrosomes and ultrasound fertility (ρ = -0.240, p = 0.021), farrowing rate (ρ = -0.244; p = 0.019), and total born (r = -0.304; p = 0.003). Average born alive was positively correlated with plasma seminal concentrations of protein (r = 0.273; p = 0.009), fructose (r = 0.243; p = 0.024) and cathepsine B (ρ = 0.257; p = 0.029) but negatively correlated with apoptosis and DNA damage nuclear markers cPARP (r = -0.295, p = 0.005) and PAR (r = -0.209, p = 0.049). However, regression models only showed significant results for predicting the total born from damaged acrosomes and those born alive from cPARP, although the coefficients of determination were very low. Since semen quality and fertility were good, most parameters did not affect fertility outcomes. In agreement with previous studies, acrosomal damage would be a reliable predictor of reproductive outcomes, whereas cPARP would show potential as a novel biomarker.

The periparturient period represents a critical window of vulnerability in livestock reproduction. Additionally, reproductive performance is often compromised due to a weakened immune system and high oxidative stress. Selenium, an essential micronutrient, emerges as a key element with dual roles in antioxidant defence and immune modulation, making it a cornerstone in maintaining reproductive health in livestock. Selenium exerts its protective effects through incorporation into selenoproteins such as glutathione peroxidase (GPx), which downregulate oxidative stress, support cellular integrity, and regulate inflammation in reproductive tissues. During the periparturient period, selenium deficiency is associated with increased production of β-hydroxybutyric acid (BHBA) and non-esterified fatty acids (NEFA), responsible for triggering lipid mobilisation and activation of the NF-κB (Nuclear Factor kappa-light-chain-enhancer of activated B cells) signalling pathway. This leads to overexpression of pro-inflammatory genes, resulting in uterine infections, mastitis, and other reproductive disorders. Selenium supplementation in organic or nano forms plays a potential role in countering these effects by activating the Nrf2 (Nuclear factor erythroid 2) pathway, boosting antioxidant enzymes, and suppressing the NF-κB pathway. In females, selenium enhances endometrial epithelial repair, hormone regulation, and immune tolerance by regulating the NF-κB signalling pathway. In males, combined supplementation of selenium with vitamin E improves sperm quality, motility, and testosterone levels while preventing lipid peroxidation in spermatozoa. At the epigenetic level, selenium influences histone acetylation to regulate transcription of inflammatory genes such as COX-2 and TNF-α. Recent insights into the role of selenium receptors (LRP8) in ovarian follicular development highlight the applications of selenium in fertility regulation. The efficacy of selenium is highly influenced by its form, dosage, animal species, and physiological state. This review emphasises the need for large-scale, species-specific research trials, nanodelivery strategies, and omics-based biomarkers to improve selenium supplementation strategies and dose rate. Selenium holds significant translational potential in veterinary reproduction, playing a preventative and therapeutic role against reproductive immunopathologies in livestock.