Banking North American buffalo semen

Quercetin in semen extender improves frozen-thawed spermatozoa quality and in-vivo fertility in crossbred Kamori goats

This study investigated the antioxidant effect of quercetin-treated semen on frozen-thawed spermatozoa quality and in-vivo fertility in crossbred Kamori goats. In total, 32 ejaculates from four fertile bucks were diluted in Tris-based egg yolk extender with varying levels of quercetin (0, 1, 5, 10, and 15 μM). Qualified semen samples were pooled and frozen in French straws. The results revealed that the addition of quercetin in the semen extender increased (p < 0.05) frozen-thawed sperm total motility (TM), progressive motility (PM), rapid velocity (RV), average path velocity (VAP), straight line velocity (VSL), curvilinear velocity (VCL), and amplitude of lateral head (ALH) displacement in contrast to the control group. Quercetin supplementation had no effect on beat cross frequency (BCF), straightness (STR), and linearity (LIN) (p > 0.05). Quercetin showed significantly higher (p < 0.05) plasma membrane and acrosome integrity and viability (p < 0.05) of spermatozoa in contrast to the control group. Quercetin in the semen extender significantly increased (p < 0.05) superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), ascorbate peroxidase (APX), and total antioxidant capacity (TAC) levels while reduced (p < 0.05) the contents of total oxidant status (TOS) and malondialdehyde (MDA), which were in contrast to the control group. Ultrasound results revealed that 24 out of 30 (80%) goats were found pregnant when semen was treated with 5 μM quercetin while the control group showed 18 out of 30 (60%) animals were pregnant. Thus, the study concluded that 5 μM quercetin-treated semen was found to be efficient, showed increased antioxidant status, and reduced oxidant production, leading to improved spermatozoa quality and in-vivo fertility in goats.

Quercetin induces its chemoprotective effects via hormesis

Quercetin is a polyphenol present in numerous fruits and vegetables and therefore widely consumed by humans with average daily dietary intakes of 10-20 mg/day. It is also a popular dietary supplement of 250-1000 mg/day. However, despite the widespread consumer interest in quercetin, due to its possible chemopreventive properties, the extensively studied quercetin presents a highly diverse and complex array of biological effects. Consequently, the present paper provides the first assessment of quercetin-induced hormetic concentration/dose responses, their quantitative features and mechanistic foundations, and their biological, biomedical, clinical, and public health implications. The findings indicate that quercetin-induced hormetic dose responses are widespread, being independent of biological model, cell type, and endpoint. These findings have the potential to enlighten future experimental studies with quercetin especially with respect to study design parameters and may also affect the appraisal of possible public health benefits and risks associated with highly diverse consumer consumption practices.

The morphology, morphometry and functionality of fresh and cryopreserved wisent (Bison bonasus) epididymal spermatozoa

Epididymal spermatozoa obtained post mortem are considered a valuable source of genetic material which is often irrevocably lost. This makes these gametes constitute a key element in protection and restitution programs. The wisent (Bison bonasus, Linnaeus 1758) is a species that survived in zoos after extinction from its natural habitat. This resulted in a narrowing of the genetic pool of the whole population, which is at present derived from only 12 ancestors. Currently, wisent protection programs are aimed at preserving the genetic diversity by establishing a germplasm bank. The objective of this study was to comprehensively characterize the morphology, morphometry and functionality of wisent epididymal spermatozoa and evaluate the effectiveness of their cryopreservation in extender based on Tris buffer and chicken egg yolk. The median total number of spermatozoa obtained from one individual was 1985.0 × 106 (62.5 × 106-7452.0 × 106). These gametes were characterized by median: 40.0% (0.5-70.0%) subjective motility, 69.8% (32.5-90.0%) viability and 54.3% (10.5-83.3%) normal morphology. The sperm head had a median size of 5.0 μm (3.5-6.7 μm) width, 8.5 μm (6.4-11.3 μm) length and 36.9 μm2 (23.7-48.6 μm2) surface area. The viable population of the obtained gametes was characterized by median values 53.2% (4.5-80.3%) of intact sperm membrane, 50.8 (26.0-76.6%) of intact acrosome, 0.4% (0-98.7%) of fragmented chromatin, 5.9% (0.0-88.8%) of cells with high mitochondrial potential and 42.1% (8.3-63.7%) without lipid peroxidation. The viable population of the frozen/thawed gametes was characterized by median values: 18.4% (2.4-57.9%) of intact sperm membrane, 35.1 (11.9-56.7%) of intact acrosome, 0.07% (0-89.2%) of fragmented chromatin, 12.8% (0.0-49.7%) of cells with high mitochondrial potential and 16.3% (2.2-53.6%) without lipid peroxidation. Due to the material originating from a relatively large number of wild individuals, the research presented here contributed to the description of certain species standards for the assessment of wisent epididymal spermatozoa. The presented effect of cryopreservation on these gametes justifies the use of an extender based on Tris buffer with the addition of chicken egg yolk. The obtained effects are satisfactory from the point of view of preserving valuable genetic material and their use in ART.

Review: Reproductive physiology of bison and application of assisted reproductive technologies to their conservation

Bison are an ecologically and culturally important species on the European and North American continents. Their near extirpation was met with conservation efforts that prevented their extinction but left few animals or highly fragmented populations. Contemporary conservation efforts are focused on building ecologically and genetically sustainable bison herds for long-term conservation of the species. Assisted reproductive technologies (ARTs) can play a key role in building these herds by facilitating the movement of genetics in the form of gametes and embryos, while protecting animal well-being and ensuring biosecurity of existing bison herds. In addition, ARTs such as gamete and embryo cryopreservation can be used to protect against future losses of genetic diversity through biobanking. In this review, a brief summary of basic bison reproductive physiology is presented followed by an overview of the current state of ART in Bison bison (American bison) and Bison bonasus (European bison or wisent). Research on ART ranging from artificial insemination to in vitro embryo transfer and cloning is discussed with particular regard to the application of ART for conservation purposes. While significant progress has been made in ART for bison, there are still many opportunities to improve these technologies and expand their impact for bison conservation.

Cholesterol-cyclodextrin complex as a replacement for egg yolk in bull semen extender: sperm characteristics post-thawing and in vivo fertility

Egg yolk, a major semen extender constituent, lacks a defined composition, therefore, there are biosecurity concerns with use of egg yolk. Cryopreservation of bull semen without inclusion of animal protein in the semen extender, therefore, is an important consideration. Cholesterol may be delivered and incorporated into the sperm plasma membrane by cyclodextrins to protect sperm during cryopreservation. The aim of this study was to determine suitability of a cholesterol-cyclodextrin semen extender, without inclusion of egg yolk, for cryopreservation of bull semen. Bull semen was collected and cryopreserved in either egg yolk or with inclusions of three different concentrations of cholesterol-cyclodextrin complex (0.5, 1 or 2 mg/mL semen) in Tris-glycerol (TG) extender. Sperm motion characteristics examined using the computer-assisted sperm analysis, and plasma membrane and acrosome integrity examined using flow cytometry, were similar for all extenders. The inclusion of the greatest concentration of cholesterol-cyclodextrin complex (2 mg/mL semen) followed by dilution in TG extender resulted in lesser pregnancy rates (P <  0.05). There was a pregnancy rate of as great as 56 % when sperm cryopreserved in 0.5 mg/mL cholesterol-cyclodextrin Tris-glycerol extender were used for artificial insemination following imposing of a hormonal treatment regimen for synchrony of timing of ovarian functions among cows for conducting fixed-time artificial insemination (FTAI). Results indicate cholesterol-cyclodextrin Tris-glycerol extender, with a chemically defined composition and without inclusion of egg yolk, may be used to cryopreserve bull sperm with there being acceptable pregnancy rates when this semen is used for FTAI.

Effect of Quercetin Supplementation in Extender on Sperm Kinematics, Extracellular Enzymes Release, and Oxidative Stress of Egyptian Buffalo Bulls Frozen-Thawed Semen

Buffalo spermatozoa are more sensitive for cryopreservation compared to other species. This study aimed to evaluate the consequences of quercetin against cryodamage of buffalo frozen–thawed spermatozoa characteristics. Semen of Egyptian bulls (n = 4) was extended in OptiXcell extender incorporated with quercetin at 0 (control), 2.5, 5.0, 10.0, 20.0, 40.0, and 80.0 μM before cryopreservation. Frozen–thawed semen was evaluated for sperm motility by computer-assisted sperm analyzer (CASA), viability, morphology, membrane, and acrosome integrities. The kinematics parameters including average path velocity (VAP; μm/s), straight linear velocity (VSL; μm/s), curvilinear velocity (VCL; μm/s), amplitude of lateral head displacement (ALH; μm), beat cross frequency (BCF; Hz), linearity [LIN, (VSL/VCL) × 100], and straightness [STR, (VSL/VAP) × 100] were assessed. The sperm-free extender was evaluated for aspartate aminotransferase (AST), alanine aminotransferase (ALT), and H₂O₂. Homogenized sperm cells were evaluated for oxidative stress biomarkers [superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX)], and lipid peroxidation [malondialdehyde (MDA)]. The highest values of total motility, progressive motility, viability, intact acrosome, and membrane integrity substantially improved with 10 μM of quercetin. STR (%) was substantially low (P < 0.01), and VCL (μm/s) and ALH (μm) were markedly high (P < 0.05) in 10 μM of quercetin. The outflow of ALT enzyme to extracellular fluid was lower with 10 μM of quercetin (P < 0.001) and higher at 2.5 μM of quercetin. The spermatozoa leaked AST was markedly lower at 5.0, 10 (P < 0.001) and 20 μM (P < 0.05) of quercetin. The activity of antioxidant enzymes was eminently low at all quercetin concentrations, and this was accompanied by the decrease in H₂O₂ in the media. SOD activity at 10–80 μM, CAT at 5.0–40 μM, and GPX at 2.5–80.0 μM of quercetin in spermatozoa were substantially low. MDA level significantly (P < 0.001) decreased at all quercetin concentrations. In conclusion, the incorporation of quercetin at the level of 10 μM is promising in improving buffalo semen characteristics and lower the freezing–thawing oxidative stress.

Cryopreservation of bison semen without exogenous protein in extender and its fertility potential in vitro and in vivo following fixed-time artificial insemination

Successful cryopreservation of bison semen is fundamental for restoration of genetic diversity in Canada's wood bison. Conventional bovine semen extenders contain animal products, such as egg yolk and milk, which are undesirable because of biosecurity risks and undefined composition. In this study, we examined the efficacy of an exogenous protein-free extender containing cholesterol-cyclodextrin complex (CC) to cryopreserve bison semen. The study also provided an opportunity to determine the effectiveness of different ovulation synchronization protocols for fixed-time artificial insemination in bison. Semen was collected from wood bison bulls via electroejaculation and cryopreserved in either Tris-egg yolk-glycerol (called 'TEYG') extender or pretreated with CC (2 mg/mL semen) and diluted in Tris-glycerol (collectively called 'CC-TG') extender. Post-thaw sperm motion characteristics and in vitro fertilization of cattle oocytes confirmed that CC alone without egg yolk protected bison sperm during cryopreservation process. In the first fertility trial, however, no pregnancy was obtained following fixed-time artificial insemination of bison cows with CC-TG extender. In a follow-up trial, low concentration of CC (1 mg/mL semen) resulted in better post-thaw sperm motion characteristics, fertility rate, and birth of live calves following fixed-time artificial insemination. Results showed that 1 mg CC/mL semen completely replaced egg yolk in bison semen extender. In addition, both follicular ablation and steroid treatment protocols provided ovulation synchrony to permit successful application of fixed-time artificial insemination in bison. This is the first report on the birth of live bison calves following fixed-time artificial insemination using semen cryopreserved in a defined extender.

Managing Genetic Diversity and Extinction Risk for a Rare Plains Bison (Bison bison bison) Population

Unfenced plains bison are rare and only occur in a small number of locations throughout Canada and the United States. We examined management guidelines for maintenance of genetic health and population persistence for a small and isolated population of plains bison that occupy the interface between a protected national park and private agricultural lands. To address genetic health concerns, we measured genetic diversity relative to other populations and assessed the potential effects of genetic augmentation. We then used individual-based population viability analyses (PVA) to determine the minimum abundance likely to prevent genetic diversity declines. We assessed this minimum relative to a proposed maximum social carrying capacity related to bison use of human agricultural lands. We also used the PVA to assess the probability of population persistence given the limiting factors of predation, hunting, and disease. Our results indicate that genetic augmentation will likely be required to achieve genetic diversity similar to that of other plains bison populations. We also found that a minimum population of 420 bison yields low probability of additional genetic loss while staying within society-based maxima. Population estimates based on aerial surveys indicated that the population has been below this minimum since 2007. Our PVA simulations indicate that current hunting practices will result in undesirable levels of population extinction risk and further declines in genetic variability. Our study demonstrates that PVA can be used to evaluate potential management scenarios as they relate to long-term genetic conservation and population persistence for rare species.

In vitro development of bison embryos using interspecies somatic cell nuclear transfer

Interspecies somatic cell nuclear transfer (interspecies SCNT) has been explored in many domestic and non-domestic animal species. However, problems arise during the development of these embryos, which may be related to species-specific differences in nuclear-cytoplasmic communication. The objectives of this study were to investigate the possibility of producing bison embryos in vitro using interspecies SCNT and assess the developmental potential of these embryos. Treatment groups consisted of cattle in vitro fertilization (IVF) and cattle SCNT as controls and wood bison SCNT, plains bison SCNT and wisent SCNT as experimental groups. Cleavage and blastocyst rates were assessed, and blastocyst quality was determined using total cell number, apoptotic incidence and relative quantification of mitochondria-related genes NRF1, MT-CYB and TFAM. These results indicate that embryos can be produced by interspecies SCNT in all bison species/subspecies (13.34-33.54% blastocyst rates). Although increased incidence of apoptosis was observed in bison SCNT blastocysts compared to cattle SCNT controls (10.45-12.69 vs 8.76, respectively) that corresponded with significantly lower cell numbers (80-87 cells vs >100 cells, respectively), no major differences were observed in the expression of NRF1, MT-CYB and TFAM. This study is the first to report the production of bison embryos by interspecies SCNT. Blastocyst development in all three bison species/subspecies was greater than the rates obtained in previous studies by IVF, which supports the potential role of SCNT for in vitro embryo production in this species. Yet, further investigation of developmental competence and the factors influencing blastocyst quality and viability is required.

Effects of pipothiazine palmitate on handling stress and on the characteristics of semen collected by electroejaculation in bison (Bison bison) bulls

Handling North American bison can pose risk to the handler and evoke stress in the animal. Moreover, this induced stress might affect qualities of semen collected by electroejaculation. The objective of this study was to investigate if a long acting neuroleptic tranquilizer (LAN) would reduce the stress of bison and thereby improve the quality of electroejaculated semen. Eight experimental replicates were conducted between May and November. In each replicate, the same six bison bulls were randomly assigned into LAN-treated (n=3) and non-treated control (n=3) groups. Pipothiazine palmitate (Piportil L4) was administered intramuscularly as a single dose of 100 mg in replicates 1-4 or 200 mg in replicates 5-8. Within each replicate, semen was collected by electroejaculation at 4, 6, 11 and 13 days post treatment. Behavioral parameters, sperm morphology and motility parameters were analyzed. A blood sample was collected before each electroejaculation and serum concentrations of testosterone, cortisol and corticosterone were determined. Treatment bulls with 100 mg of Piportil L4 reduced the restraint time and the struggling of bison bulls during handling compared to the control group (P<0.05). Semen motility parameters and serum concentrations of testosterone, cortisol and corticosterone were not significantly affected when 100mg of the LAN was administered (P>0.05). However, giving 200 mg of Piportil L4 reduced the restraint time of bison bulls and the duration of semen collection (P<0.05). Also, this treatment improved total and progressive sperm motilities when compared to the respective controls (P<0.05). Interestingly, serum concentration of corticosterone, as an endocrine stress indicator, was decreased after administration of 200mg of Pipothiazine palmitate, while testosterone concentrations were increased compared to those values in untreated control bulls (corticosterone: 0.10±0.01 compared with 0.15±0.02 ng/mL; testosterone: 9.11±1.68 compared with 5.33±0.74 ng/mL; P<0.05). In conclusion, this study demonstrated that a treatment dose of 200mg of Piportil L4 can decrease the behavioral and endocrine stress responses in bison bulls, which indirectly increasing testosterone concentrations and improving semen quality.

Investigation into developmental potential and nuclear/mitochondrial function in early wood and plains bison hybrid embryos

Studies to date have shown that bison embryo development in vitro is compromised with few embryos developing to the blastocyst stage. The aim of this study was to use bison-cattle hybrid embryos, an interspecific cross that is known to result in live offspring in vivo, as a model for assessing species-specific differences in embryo development in vitro. Cattle oocytes fertilized with cattle, plains bison and wood bison sperm were assessed for various developmental parameters associated with embryo quality, including cell number, apoptosis and ATP content. Decreased development to the blastocyst stage was observed in hybrid wood bison embryos compared with the other treatment groups. Although both wood bison and plains bison hybrid blastocysts had significantly lower cell numbers than cattle blastocysts, only wood bison hybrid blastocysts had a greater incidence of apoptosis than cattle blastocysts. Among the treatment groups, ATP levels and expression profiles of NRF1, TFAM, MT-CYB, BAX and BCL2 were not significantly different in both 8- to 16-cell stage and blastocyst stage embryos. These data provide evidence of decreased developmental competence in the wood bison hybrid embryos, owing to inadequate culture conditions that have increased apoptotic events.

Xenografting of testis tissue from bison calf donors into recipient mice as a strategy for salvaging genetic material

The objective was to evaluate the long-term outcome of testis tissue xenografting from neonatal bison calves as a model for closely related rare or endangered ungulates. Testis tissue was collected postmortem from two newborn bison calves (Bison bison bison) and small fragments of the tissue were grafted under the back skin of immunodeficient recipient mice (n = 15 mice; eight fragments/mouse). Single xenograft samples were removed from representative recipient mice every 2 mo after grafting (for up to 16 mo). The retrieved xenografts were evaluated for seminiferous tubular density, tubular diameter, seminiferous tubular morphology, and identification of the most advanced germ cell type. Overall, 69% of the grafted testis fragments were recovered as xenografts. Xenografts weight increased (P < 0.02) approximately four-fold by 2 mo and 10-fold by 16 mo post-grafting. In testis xenografts, gradual maturational changes were evident, manifested as the first detection of the following at the times specified: seminiferous tubule expansion, 2 mo; spermatocytes, 6 mo; round spermatids, 12 mo; and elongated spermatids, 16 mo. Furthermore, there were differences between the two donor calves regarding the efficiency of spermatogenesis in xenografts. The timing of complete spermatogenesis approximately corresponded to the reported timing of sexual maturation in bison. This study demonstrated, apparently for the first time, that testis tissue xenografting from neonatal bison donors into recipient mice resulted in testicular maturation and complete development of spermatogenesis in the grafts.