Epidermal growth factor alleviates the negative impact of urea on frozen-thawed bovine sperm, but the subsequent developmental competence is compromised

A systematic review identifying seminal plasma biomarkers and their predictive ability on IVF and ICSI outcomes

The diverse nature and high molecule concentration of seminal plasma (SP) makes this fluid a good potential source for a potential biomarker that could predict assisted reproductive technology (ART) outcomes. Currently, semen quality parameters cannot accurately predict ART outcomes. A systematic literature search was conducted to identify human SP biomarkers with potential predictive ability for the outcomes of IVF and intracytoplasmic sperm injection. Observational cohort and case-control studies describing the association between biomarkers in human SP and the outcome of infertile men attending for ART were included. Forty-three studies were selected, reporting on 89 potential SP biomarkers (grouped as oxidative stress, proteins glycoproteins, metabolites, immune system components, metals and trace elements and nucleic acids). The present review supports 32 molecules in SP as potentially relevant biomarkers for predicting ART outcomes; 23 molecules were reported once and nine molecules were reported in more than one study; IL-18 and TGF-β1-IL-18 ratio were confirmed in distinct studies. This review presents the most comprehensive overview of relevant SP biomarkers to predict ART outcomes to date, which is of clinical interest for infertility investigations and assisted reproduction; nevertheless, its potential is under-exploited. This review could serve as starting point for designing an all-encompassing study for biomarkers in SP and their predictive ability for ART outcomes, and for developing a non-invasive diagnostic tool.

Counteract severe heat stress by including different forms of zinc in the rabbit bucks' diet

The harmful influences of global warming on rabbit reproduction and industry attract global attention. Zinc (Zn) is an important trace element with a wide list of functions in the male reproductive system. The aim of this study was to estimate the effects of different forms of zinc supplementation, as organic (Zn methionine), nano (nano Zn oxide) as indirect way to minimized it impact on environment, and inorganic (Zn sulphate) on physiological parameters, semen quality, anti-oxidative status, hormonal profiles of male rabbits subjected to server heat stress. Thirty-six V-line bucks (6-7 months old, 2842.29 ± 34.46 g weight) were randomly distributed to 4 groups, bucks in 1st group (control group, Con) fed basal diet without Zn supplementation, the 2nd, 3rd and 4th groups fed basial diet with 30 mg/kg of zinc methionine (Zn-Met), nano zinc oxide (ZnO-NPs), and zinc sulphate (Zn-S), respectively for a period of 10 weeks suffered from severe heat stress of environmental ambient temperature (over 32 of temperature humidity index, THI). Semen samples were collected and evaluated for volume, pH, motility, concentration, viability, initial fructose, and seminal plasma antioxidant concentration. Liver, kidney function, hormonal and antioxidant profile were measured in blood serum. The results revealed that, compared to control, all forms of Zn supplementation used significantly improved kidney function (creatinine), serum antioxidant (SOD and CAT), physiological parameters, especially on 1st month of the experiment, and seminal plasma antioxidant (SOD and CAT) of heat stressed bucks. Likewise, semen quality in terms of sperm concentration, sperm viability, and initial fructose enhanced significantly (P ≤ 0.05) by ZnO-NPs supplementation. Zinc methionine supplementation significantly improved liver function and decreased seminal plasma TBARs. Treatments with Zn-Met and ZnO-NPs increased seminal TAC and blood testosterone levels with reduced blood cortisol levels compared to other groups. Severe heat stress could be counteract by inclusion Zn with studied forms Zn-Met and ZnO-NPs at recommended dose (30 mg/kg diet) to improve semen quality and antioxidant status.

Optimizing Bull Semen Cryopreservation Media Using Multivariate Statistics Approaches

Cryo-injury reduces post-thaw semen quality. Extender components play a protective role, but existing experimental approaches do not elucidate interactions among extender components, semen samples, and post-thaw quality. To identify optimal concentrations for 12 extender ingredients, we ran 122 experiments with an I-optimal completely random design using a large dataset from our previous study. We obtained a maximum predicted total motility of 70.56% from an I-optimal design and 73.75% from a Monte Carlo simulation. Individual bull variations were significant and interacted with extenders independently. 67% of bulls reliably preferred extender formulations to reach maximum motility. Multifactor analysis suggests that some antioxidants may offer superior protection over others. Partial least squares path modeling (PLS-PM) found the highest positive loadings for glutathione in the antioxidant class, glycerol in the CPA class, and fructose in the basic compounds class. The optimal ranges for milk, water, and ethylene glycol were extremely narrow. Egg yolk, cholesterol-loaded cyclodextrin, and nerve growth factor had medium-loading impacts. PLS-PM showed that CPA, osmoregulators, and basic components were the most efficient contributors to motility, while the antioxidant and extracellular protectant classes had less efficiency. Thus, ingredients, concentrations, and interactions of extender compounds are critical to extender formulation, especially when using multiple compounds with the same function.

Machine learning and hypothesis driven optimization of bull semen cryopreservation media

Cryopreservation provides a critical tool for dairy herd genetics management. Due to widely varying inter- and within-bull post thaw fertility, recent research on cryoprotectant extender medium has not dramatically improved suboptimal post-thaw recovery in industry. This progress is stymied by the interactions between samples and the many components of extender media and is often compounded by industry irrelevant sample sizes. To address these challenges, here we demonstrate blank-slate optimization of bull sperm cryopreservation media by supervised machine learning. We considered two supervised learning models: artificial neural networks and Gaussian process regression (GPR). Eleven media components and initial concentrations were identified from publications in bull semen cryopreservation, and an initial 200 extender-post-thaw motility pairs were used to train and 32 extender-post-thaw motility pairs to test the machine learning algorithms. The median post-thaw motility after coupling differential evolution with GPR the increased from 52.6 ± 6.9% to 68.3 ± 6.0% at generations 7 and 17 respectively, with several media performing dramatically better than control media counterparts. This is the first study in which machine learning was used to determine the best combination of constituents to optimize bull sperm cryopreservation media, and provides a template for optimization in other cell types.

Effect of Epidermal Growth Factor (EGF) on Cryopreserved Piedmontese Bull Semen Characteristics

The purpose of this study was to determine the effect on fresh and post-thaw beef bull semen quality of the supplementation of epidermal growth factor (EGF) to the semen extender at various concentrations (0-control, 50, 100, 200, and 400 ng/mL). For 8 weeks, sperm was collected from four fertile bulls, yielding a total of 32 ejaculates. Semen samples were pooled, diluted with Bullxcell^® extender, and then cooled, equilibrated, and frozen. After thawing, semen was tested for motility and velocity parameters. Furthermore, semen was evaluated for vitality, integrity, mitochondrial and antioxidant (SOD) activities, mucus penetration distance, and in vitro fertilizing capability. The supplementation with EGF prior to cryopreservation improved the total sperm motility at various concentrations over long incubation periods (from 1 to 4 h). Interestingly, EGF addition improved both progressive and rapid motility, particularly at 50, 200, and 400 ng/mL. In addition, EGF, primarily at 200 and 400 ng/mL, significantly increased several velocity parameters after different incubation periods. We can conclude that adding EGF to bull sperm extender before cryopreservation has a positive stimulatory effect on sperm motility without affecting vitality, integrity, or in vitro fertilizing capability.

Supraphysiological concentration of urea affects the functional competence of Holstein-Friesian (Bos taurus) sperm

To understand the effects of urea on sperm functional attributes, fresh bull semen (n = 12) was subjected to four different concentrations (mg/mL) of urea to mimic the physiological (0.04 and 0.13), supraphysiological (0.43) concentrations and control (0 mg/mL). Sperm membrane integrity, kinematics, chromatin integrity, and mitochondrial membrane potential were assessed at different time points (before incubation, 0, 1, 2, and 4 h) of incubation. The concentration of urea in serum and seminal plasma was estimated and correlated with the ejaculate rejection rate and sperm functional attributes. The relative expression of urea transporter gene transcripts (UT-A and UT-B) was assessed in sperm and testis (control) using real-time PCR. The supraphysiological concentration of urea affected sperm kinematics, viability, functional membrane integrity, and acrosome integrity within 1 h of incubation (p < 0.05). Sperm head area decreased (p < 0.05) at 0 h and subsequently increased at 1 h of incubation in all media except supraphysiological (0.43 mg/dL) concentration of urea. Seminal plasma urea concentration showed a significant negative correlation with sperm motility, membrane integrity, and mitochondrial membrane potential (p < 0.05), but had a positive correlation with the ejaculate rejection rate (r = 0.69). Relative expression of the urea transporter genes revealed that UT-A was expressed only in the testis. In contrast, UT-B was expressed in both the testis and sperm, suggesting UT-B's role in regulating urea transport in sperm. At a supraphysiological level, urea adversely affected sperm functional attributes, osmoadaptation and may affect fertility.