Influence of Non-conventional Sperm Quality Parameters on Field Fertility in Ovine

The characterization of CellROX™ probes could be a crucial factor in ram sperm quality assessment

Several authors have demonstrated that low levels of reactive oxygen species (ROS) are necessary for the physiological functions of sperm, such as capacitation, hyperactivation, acrosomal reaction and fertilization. However, high levels of ROS are associated with oxidative stress and detrimental effects on fertility. Consequently, deep characterization of ROS presence using different fluorescent probes could be crucial. In this sense, the study of intracellular ROS localization and the relationships between ROS and other conventional parameters could improve the characterization of sperm quality for semen preservation protocols in rams. In this work, a multiparametric study was carried out by analyzing four experimental groups of ram sperm with different initial qualities: fresh semen (from both breeding and nonbreeding seasons), frozen-thawed semen and, a positive control group treated with hydrogen peroxide (300 μM) as a marker of extreme damage. Sperm analyses, including viability, apoptosis, lipid peroxidation, motility and kinetic parameters, were applied to compare several experimental groups with different sperm qualities. After that, the signals from two different ROS probes: CellROX™ Deep Red (CRDR) and Green (CRG), were examined by flow cytometry (percentage of cells that express ROS) and fluorescence microscopy (intracellular ROS location). Comparing conventional parameters, fresh samples from the breeding season showed the highest sperm quality, while the positive control samples showed the worst sperm quality. Concerning the ROS probes, the CRDR levels were higher in fresh samples from the breeding season than in the positive control and cryopreserved samples. Surprisingly, CRG presented its highest level (P < 0.05) in the positive control group treated with peroxide by flow cytometry. CRDR and CRG presented opposite labeling patterns that were corroborated by fluorescence microscopy, which determined that the probes localized in different parts of sperm. CRDR was found in the sperm mitochondrial region, while CRG was observed in the cell nucleus, suggesting that ROS localization is an important factor. Finally, our study indicates that CRDR is correlated with proper viability and sperm motility, and could be associated with high mitochondrial activity, while CRG is associated with sperm damage.

Exploring Endogenous and Exogenous Factors for Successful Artificial Insemination in Sheep: A Global Overview

Artificial insemination (AI) plays a vital role in animal breeding programs. AI is applied to enhance animal genetics and facilitate the widespread integration of desirable characteristics with a high potential for productivity. However, in sheep, this biotechnology is not commonly practicable due to multi-factorial challenges, resulting in inconsistent outcomes and unpredictable results. Thoughtful selection of semen donors and recipients based on genetic merit deeply impacts ovine AI outcomes. Additionally, endogenous factors such as breed, age, fertility traits, genetic disorders, and cervical anatomy in ewes contribute to ovine AI success. Extensive research has studied exogenous influences on sexual behavior, reproductive health, and hormonal regulation, all impacting ovine AI success. These exogenous factors include techniques like estrus induction, synchronization, semen handling methods (fresh/chilled/frozen), and insemination methods (cervical/laparoscopic), as well as nutritional factors and climatic conditions. This overview of the literature highlights the endogenous and exogenous challenges facing successful ovine AI and proposes strategies and best practices for improvement. This paper will serve as a guide for understanding and optimizing the success of ovine AI.

Effect of season on the dynamics of cat sperm DNA fragmentation

BACKGROUND

Feline species undergo reproductive seasonality; thus, sperm characteristics, such as DNA integrity, can be affected by the photoperiod. This study was conducted to determine the effect of seasonal changes on sperm quality and on the dynamics of sperm DNA fragmentation. Epididymal spermatozoa were collected from 36 tomcats subjected to bilateral orchiectomy during breeding (BS) and non-breeding (NBS) seasons. Sperm samples were obtained by cutting the cauda epididymis and assessed for sperm motility, concentration, acrosome integrity, plasma membrane integrity and sperm morphology. Sperm DNA fragmentation was evaluated by the sperm chromatin dispersion test after 0, 6, and 24 h of incubation at 37 °C.

RESULTS

The total sperm motility and plasma membrane integrity values were greater during the BS, while the percentages of abnormal sperm and head defects were lesser (p < 0.05). No significant differences in DNA fragmentation were found between seasons after sperm collection. DNA damage was greater after 24 h of incubation at 37 °C in both seasons, although the percentage of spermatozoa with fragmented DNA was significantly lesser in the BS than in the NBS at 24 h (p < 0.05).

CONCLUSIONS

The study suggests seasonal changes in some of the quality parameters of cat sperm. DNA fragmentation dynamics were affected by the time of incubation and reproductive season; therefore, this technique might be used as an additional tool to test the potential fertility of semen samples used in feline-assisted reproduction.

Association between different soy lecithin-based extenders and freezing rates in ram semen cryopreservation

The aim of the study was to evaluate the effect of the association between glycine-milk (GM) based extenders made with different concentrations of soy lecithin (SL) and freezing rates (FR) on semen quality after thawing. Pooled semen from rams (n = 12) were diluted in GM extenders with 20% egg yolk (EY-20%) or with different concentrations of SL: 0.5% (SL-0.5%), 1.0% (SL-1.0%), and 2.0% (SL-2.0%). The diluted semen (150 ×10⁶ spermatozoa/0.25 mL) was frozen at three FR of - 10, - 20, and - 60 °C/min, and subsequently thawed and analyzed. Results revealed that EY-20% and SL-2.0% had better kinetic parameters, and showed higher proportions of viable, non-apoptotic, plasma-membrane-intact spermatozoa (A^-/PI^-) and non-capacitated spermatozoa (F), and had lower acrosome-reacted spermatozoa (AR) in the EY-20% and satisfactory values for SL-2.0% compared to SL-0.5% and SL-1.0% (P < 0.05). The FR at - 20 and - 60 °C/min maintained higher A^-/PI^- and viable spermatozoa compared to - 10 °C/min. The combination EY-20% and - 60 °C/min showed the highest A^-/PI^- and F (P < 0.05) and the lowest AR, and it did not differ from the combinations EY-20% at - 20 °C/min and SL-2.0% at - 20 °C/min (P > 0.05). In conclusion, the combination EY-20% and - 60 °C/min, showed the best cryoprotective effects on ram spermatozoa. Changes in spermatozoa after thawing were related to the use of the type of extender, the amounts of the same compound in the extender, and the freezing rates to which they were subjected.

Glycerol-Free Equilibration with the Addition of Glycerol Shortly before the Freezing Procedure: A Perspective Strategy for Cryopreservation of Wallachian Ram Sperm

This study investigated the effect of glycerol added in different phases of sperm equilibration on CASA and flow cytometry parameters of thawed ram spermatozoa. Sperm was collected from adult Wallachian rams. The freezing extender was glycerol-free ANDROMED® (Minitub GmbH, Tiefenbach, Germany) supplied by 6% exogenous glycerol at different stages of the cryopreservation process. The purpose of this study was to compare two strategies of glycerol addition for sperm cryopreservation. The first strategy included the use of a glycerol-free extender for the procedure of glycerol-free equilibration and chilling, with the glycerolation of the extender by 6% glycerol shortly before sperm slow freezing (GFA). The second strategy included the use of a freezing extender already glycerolated by 6% glycerol before the equilibration and chilling of sperm and following slow freezing (GA). Sperm samples were analyzed after equilibration (but before freezing) and after thawing (at T0, T1 h, and T2 h time points). iSperm® mCASA (Aidmics Biotechnology Co., LTD., Taipei, Taiwan) was used for the evaluation of sperm kinematics. Flow cytometry was used to measure sperm viability (plasma membrane/acrosome intactness) and mitochondrial membrane potential. The obtained results significantly demonstrated that the glycerol-free equilibration with the addition of glycerol shortly before freezing is a perspective strategy for cryopreservation of Wallachian ram sperm.

Fertility prediction in dairy goats from Murciano-Granadina breed: The role of sperm evaluation and female traits

Fertility is one of the most economically important traits in farm animals, due to the direct and indirect costs associated to low pregnancy rates. Thus, one of the priority goals in animal reproduction is to predict the performance that the semen doses will have in vivo based on the quality values obtained in laboratory assays. Attempts have been made for getting a predictive model of fertility of frozen-thawed sperm in dairy goats, but similar studies have not been conducted for chilled goat buck sperm doses that are mostly used for artificial insemination in many countries including Spain. We study how parameters of in vitro sperm quality and characteristics of Murciano-Granadina dairy goats may affect the in vivo fertility obtained after artificial insemination with semen doses chilled at 4 °C. Moreover, this information was used for obtaining predictive models of the fertility. Sixty-three ejaculates from 13 males were used to prepare chilled doses for the insemination of 495 goats over 13 sessions. Fresh and chilled sperm were evaluated for motility and plasma membrane integrity with a computer-assisted sperm analysis system and flow cytometry, respectively. Fertility was determined at parturition, according to the kidding goats. Overall fertility was 59.6%. Pearson's correlation coefficients between in vivo fertility and quality variables of fresh sperm were not significant and were low (below 0.34 in absolute value) for chilled sperm. Females' characteristics had a low negative impact on fertility (correlation coefficients of -0.19 with age, -0.20 with parturitions and -0.11 with total milk yield obtained in the best lactation). Fixed and mixed logistic regression procedures were used trying to explain the fertility results. None of the models accurately predicted fertility, but the best models included the percentage of total motile sperm or average path velocity from fresh semen, age of the females and the session effect (uncontrolled environmental effects). These analyses showed that primiparous goats were 2.42 times more likely to get pregnant than goats that had kidded four or more times. Our field assay data on fertility in Murciano-Granadina dairy goats highlighted the importance of making quality controls of sperm, of choosing the doses presenting high percentages of motile sperm exhibiting regular trajectories and of selecting the youngest goats for AI, after their first kidding. Efforts should continue to obtain better predictive models for improving fertility in goat dairy herds.

Testicular Ultrasound Analysis as a Predictive Tool of Ram Sperm Quality

Simple Summary

In animal production, the prediction of male fertility is vital for the success of specific techniques such as artificial insemination. Thus, testicular ultrasound, a non-invasive diagnostic procedure, could be a useful tool. Moreover, recent ultrasound-video analysis and software developments allow the visualization of tissue at the microscopic level. The objective of this work was to establish a possible correlation between testicular ultrasonography and semen quality in rams. For this purpose, the testicles of nine rams were evaluated and the semen was analyzed for one year. The results revealed that the number of white and grey pixels correlated with sperm parameters indicating poor seminal quality. On the other hand, the increase in the seminiferous-tubule density or the lumen area of these tubules was related to a rise in seminal quality. Therefore, ultrasound-video analysis could be a good tool for evaluating the fertility of rams, either for artificial insemination or on the farm.

Abstract

Testicular ultrasound is a non-invasive technique that could be very useful for predicting ram seminal quality. Recent software developments allow macroscopic and microscopic evaluation of testicular parenchyma. Thus, the aim of this study was to evaluate the testicular echotexture using ultrasound-video analysis and investigate its possible correlation with semen quality. Nine rams were evaluated for one year using a portable ultrasound scanner and the echotexture was analyzed with ECOTEXT^® software. The number of black (Ec1), white (Ec2), and grey pixels (Ec3), tubular density (TD), lumen area (LA), and lumen diameter (LD) were analyzed. Semen was collected by an artificial vagina the same day and the sperm concentration, morphology, motility, viability, phosphatidylserine (PS) translocation, reactive-oxygen-species (ROS) levels, DNA damage and capacitation state were evaluated. Ec2 and Ec3 correlated positively with “bad quality” sperm parameters (the percentage of spermatozoa with high ROS levels, with PS translocation and proximal cytoplasmic droplets), and negatively with motility. In contrast, TD and LA showed a positive correlation with “good quality” parameters (motility or normal morphology) and a negative correlation with spermatozoa with high ROS levels, with DNA fragmentation, and proximal or distal cytoplasmic droplets. Thus, echotexture analysis by ultrasound-video analysis could be a valuable tool for assessing ram fertility.