Animal Reproduction最新文献

Sperm cells require time to adjust to lower temperatures. While some studies have established stabilization periods ranging from two to four hours for ovine semen, the exploration of longer periods of stabilization remains limited. The objective of the study is to evaluate the 12-hour refrigeration curve during ovine semen cryopreservation and the impact of a diluent medium containing egg yolk and liposomes. Eight mixed-breed rams (½ Dorper and ½ Santa Inês) provided two ejaculates each, divided into two groups. Group A used a commercial egg yolk-based diluent (Botu-Bov® - Botupharma Ltda, Brazil), while Group B used a commercial liposome-based diluent (OptiXcell®, IMV Technologies, France). Semen was packaged in French straws, cooled, cryopreserved, and thawed for analysis. Group A exhibited superior values (P < 0.05) in progressive motility (MP), progressive linear velocity (VSL), straightness (STR), and linearity (LIN) post-thawing and after 3 hours at 37°C (TTR). Conversely, Group B showed higher (P < 0.05) values for path velocity (VAP), curvilinear velocity (VCL), lateral head displacement amplitude (ALH) post-thawing, and VAP, VSL, VCL, and ALH after TTR. Flow cytometry revealed Group A's higher (P > 0.05) plasma and acrosomal membrane integrity and membrane stability. However, Group B exhibited greater (P > 0.05) superoxide anion generation and lipid peroxidation, indicative of higher oxidative stress. In conclusion, the egg yolk-based diluent outperformed the diluent containing liposomes in sperm kinetic parameters evaluated by CASA, although liposomes showed increased oxidative stress, 12 hours of refrigeration at 5.0°C is an alternative viable for semen cryopreservation in sheep.

Hypertension is an age-related pathology that causes a decline in the function of all organ systems, including the reproductive system, due to its association with increased oxidative stress and inflammation. The inflammatory cytokine levels increase as a result of hypertension and cause inflammation and tissue injury. Although high-intensity interval training (HIIT) has shown promise as a nondrug treatment for hypertensive individuals, its effects on the reproductive system of hypertensive individuals remain unknown. The aim of this study was to investigate the effects of HIIT on plasma hormone concentrations and the expression of inflammatory mediators in the testes of spontaneously hypertensive rats (SHRs). Male SHRs were divided into 2 groups: SHR (control, n=8) and HIIT (SHRs subjected to HIIT on a treadmill for 8 weeks, n=9) groups. The expression of inflammatory mediators (TNFα and IL-6) in the testes and testosterone, prolactin, and corticosterone concentrations in plasma were measured. No difference in TNFα expression was found between the groups. The groups also showed no significant differences in hormone levels. However, SHRs that underwent HIIT showed lower immunostaining for IL-6 in their testes than did SHRs that did not undergo HIIT training (P < 0.05) and the HIIT group presented lower lower systolic blood pressure than did the SHR group. We concluded that HIIT for two months reduces the BSP and IL-6 levels in the testes of hypertensive rats.

Elevated temperature-humidity index (THI) levels, common in subtropical summers, can impair bovine oocyte development by increasing reactive oxygen species (ROS) accumulation, leading to oxidative stress and reduced developmental competence. Alpha-tocopherol, a potent antioxidant, has the potential to mitigate these effects by scavenging ROS. However, its seasonal efficacy during bovine oocyte in vitro maturation (IVM) remains underexplored. This study evaluated the impact of 100 µM α-tocopherol supplementation during IVM on oocytes collected in spring (THI: 68.7±3) and summer (THI: 73±3) in Northern Uruguay. Oocytes underwent IVM, fertilization, and embryos were cultured in vitro until day 9 post-fertilization. Blastocysts were assessed for ROS levels, apoptosis, and the abundance of transcripts linked to development and oxidative stress. Results showed a season-specific response to α-tocopherol supplementation. While no significant effects were observed in spring, summer oocytes exhibited increased maturation, cleavage, and blastocyst rates, along with improved blastocyst quality characterized by reduced apoptosis and lower BAX transcript levels. These findings indicate that α-tocopherol supplementation during IVM enhances oocyte developmental competence under heat stress conditions, supporting its potential as a strategy to mitigate oxidative damage and improve bovine embryo production during summer.

It remains a problem to efficiently improve the boar sperm quality of liquid storage due to reactive oxygen species (ROS) accumulation. To reduce the effects of ROS on boar sperm, in this study, 1 μg/mL zinc oxide nanoparticles (ZnO NPs) was added into the extender of boar semen during liquid storage at 4°C and 17°C for 7 days. The finding revealed that sperm motility, viability, plasma membrane integrity (PMI) and acrosome integrity significantly increased when compared with the control group (P ˂ 0.05) Additionally, ZnO NPs significantly increased the levels of adenosine triphosphate (ATP), mitochondrial membrane potential (MMP), and antioxidation abilities (P ˂ 0.05) in boar sperm. Moreover, ZnO NPs could protect boar sperm from oxidative stress (OS) by inhibiting ROS-induced decrease of phosphorylation of PKA substrates (P-PKAs). Together, the current results suggest that ZnO NPs could be used as a novel antioxidant agent for semen preservation, which is helpful in improving the application of assisted reproductive technology in domestic animals.

Repeat breeder (RB) syndrome plays a detrimental role on fertility and economic performance of dairy farms. Regarding its multifactorial origin, it has been stated that an immunological response in the female genital tract may impair sperm viability. Therefore, the aim of this study was to evaluate the concentration of immunoglobulins in cervical mucus of RB cows and its influence on sperm motility. Fifteen fertile cows and 32 RB cows were included in the study. Cervical mucus samples were collected at the time of artificial insemination (AI). The concentration of IgG and IgA was determined by radial immunodiffusion. Sperm motility in cervical mucus was evaluated by CASA system. Our results showed no significant differences between cows with or without RB syndrome regarding the concentration of immunoglobulins in cervical mucus and sperm motility. The only factor affecting sperm motility was time. Consequently, it may be probable that a local immune response against spermatozoa is not one common cause of RB syndrome.

Successful implementation of conservation programs for endangered species requires biological material for use in reproductive biotechnologies. This enhances reproductive efficiency and helps increase the populations of critically endangered species. One way to facilitate the exchange of genetics between captive and free-ranging animals is through the creation of cryogenic banks that store cryopreserved gametes. In particular, semen cryopreservation allows for this exchange to occur. We evaluated whether the use of exogenous hormones (such as oxytocin and prostaglandin) prior to electroejaculation increases seminal volume, sperm concentration, and the number of doses produced in the red brocket deer (Mazama rufa). We also evaluate whether seminal parameters vary over the three stimulation cycles of the same electroejaculation procedure. The treatments did not affect ejaculate volume (p = 0.402), the number of sperm cells in the ejaculates (p = 0.926), total doses produced (p = 0.684), sperm mass movement (p = 0.229), sperm cell concentration (p = 0.106), and acrosome integrity (p = 0.210). The use of hormones has potential in reducing the need for stressful stimuli in electroejaculation, but the choice of hormones must take into account their effects on semen quality.

Small ruminant farming plays a pivotal role in agriculture, especially in developing countries due to sheep's diverse functions and capacity to acclimate to varying temperatures. This review comprehensively explored the impact of rising temperatures on reproductive processes, reproductive function encoding gene expression, and sheep's ability to adapt to heat stress. Several mechanisms contribute to sheep's resilience to heat stress, encompassing morphological, behavioral, physiological, and genetic adaptations. It has been shown that heat stress compromises fertility by affecting follicular development, ovulation rate, estrous behavior, rates of conception, embryonic survival, and fetal development, while also disrupting sperm production and motility, and increasing the incidence of structurally abnormal sperm in males. Estimates suggested that heat stress may reduce conception rates from 20% to 27%. Essential genes encoding the Gonadotrophin-releasing hormone, Follicle-stimulating hormone receptor, Luteinizing hormone receptor, Estradiol receptor, progesterone receptor, and Inhibin play a critical role in elucidating how heat stress impacts the reproductive performance of sheep. Furthermore, the resilience of sheep in facing heat stress adversities is associated with a specific heat shock factor. When an animal is under heat stress, Heat shock factors get activated and stimulate the production of Heat Shock Proteins (HSPs). Emphasis should be given to identifying specific genes and candidate genes that confer protection against heat stress and conducting comprehensive research to unravel how sheep adapt to demanding local climatic conditions to enhance production and profitability, improve animal welfare, and for genetic conservation and breeding programs.

Porcine breeding industries typically ensure the viability of boar artificial insemination doses during a 5-day liquid storage period at 17 °C. This study aimed to investigate whether the addition of L-carnitine (LC) to boar semen doses on different days of cooled storage could extend their usability. In experiment 1, LC was added to porcine semen doses on the fifth day (d5) of cooled storage performing five treatments control (no LC), 0.5, 1-, 5- and 10-mM LC. On d6 and d8 of storage, semen samples were evaluated for sperm motility and kinematic parameters, membrane functionality, and hydrogen peroxide and nitrite concentrations. In experiment 2, the number of sperm bound to the zona pellucida (ZP) was determined, as a way to investigate sperm penetration capability from boar insemination doses, with co-incubation with porcine oocytes. LC concentration that produced the most favorable outcomes in Experiment 1 was chosen to experiments 2 and 3, performing two treatments in the absence and with the LC. In Experiment 3, LC was added to cooled porcine semen doses after one day of storage (d1), and the same evaluations of experiment 1 were conducted on days 5, 7, 9, and 12, including sperm membrane integrity. The addition of 10 mM LC on d5 and d1 of storage improved sperm motility, which was extended up to 8 and 12 days of cooled storage, respectively. LC addition on d5 of storage increased sperm membrane functionality, while when added to semen on d1 of storage, it decreased NO₂ ^- concentration on d9. On d6 of cooled storage 10 mM LC increased the number of sperm bound to ZP compared to the control. In conclusion, adding 10 mM LC to porcine semen doses at 17 °C improved sperm characteristics and ZP binding, ultimately enhancing sperm viability for up to 12d.

The objective of this study was to investigate the effects of GnRH at insemination on pregnancy and lambing in seven ewe populations during the breeding season. Estrus was synchronized in 1560 adult ewes using an intravaginal sponge impregnated with flurogestone acetate. The sponge was left in the vagina for 12 days followed by an injection of 330 IU of eCG at sponge removal. Each ewe was inseminated twice at 48 h and 60 h after sponge removal. The treatment group was intramuscularly injected at the first insemination with a dose of 16 μg GnRH and the control group with saline solution in each ewe population. The results showed that GnRH administration significantly decreased the pregnancy rate in three ewe populations, but had no effects in four ewe populations. Additionally, the litter size tended to increase in the treatment group compared to the control group in all seven ewe populations, but the difference was not significant. In conclusion, GnRH administration at insemination was not recommended for ewes undergoing a timed artificial insemination during the breeding season. The breed/population may be a critical determinant of the potential for exploiting GnRH application in sheep breeding programs.

Anti-Müllerian Hormone (AMH), a member of the TGF-β superfamily, plays a critical role in mammalian fertility. This study aimed to investigate AMH concentrations in pregnant buffalo cows and their fetuses, and to characterize the cellular distribution and immunolocalization of AMH within fetal gonads. Gonads were collected from 12 male and 14 female buffalo fetuses, fixed in 10% buffered formalin, and processed for routine histological analysis and immunohistochemical localization of AMH. Blood samples were collected from 26 pregnant buffalo cows and their corresponding fetuses into EDTA-coated tubes. AMH levels in both maternal and fetal blood were quantified using a commercially available bovine AMH ELISA kit. Significant (p < 0.05) inter-individual variations in maternal and fetal AMH concentrations were observed. In males, fetal AMH concentrations increased significantly with gestational age, with levels substantially higher compared to females at all gestational ages (52-1222 times higher). Immunohistochemistry revealed intense AMH immunoreactivity in the cytoplasm of pre-Sertoli cells in male fetuses. In females, no significant correlation was found between fetal AMH concentrations and follicular populations, although intense AMH immunostaining was observed in the cytoplasm of oocytes within primordial follicles. These findings suggest that fetal AMH concentrations in buffaloes are influenced by gestational age and sex, and that fetal AMH likely does not readily cross the placental barrier. Further investigations are warranted to elucidate the intricate role of AMH in gonadal development and function in buffaloes.