A sexually transmitted sugar orchestrates reproductive responses to nutritional stress.

Seminal fluid is rich in sugars, but their role beyond supporting sperm motility is unknown. In this study, we found Drosophila melanogaster males transfer a substantial amount of a phospho-galactoside to females during mating, but only half as much when undernourished. This seminal substance, which we named venerose, induces an increase in germline stem cells (GSCs) and promotes sperm storage in females, especially undernourished ones. Venerose enters the hemolymph and directly activates nutrient-sensing Dh44+ neurons in the brain. Food deprivation directs the nutrient-sensing neurons to secrete more of the neuropeptide Dh44 in response to infused venerose. The secreted Dh44 then enhances the local niche signal, stimulating GSC proliferation. It also extends the retention of ejaculate by females, resulting in greater venerose absorption and increased sperm storage. In this study, we uncovered the role of a sugar-like seminal substance produced by males that coordinates reproductive responses to nutritional challenges in females.

Identification of semen traces at a crime scene through Raman spectroscopy and machine learning.

Biological fluid stains can be instrumental in solving crimes. Identification of semen can help reconstruct events in sexual assault cases and identify suspects via DNA profiling. Current methods for semen identification suffer from limitations, including destruction of the sample and potential false positives. One of the main unsolved issues is the elimination of underlying substrate interference. In this paper, chemometric approaches were developed to isolate and identify a biofluid stain on interfering substrates using Raman spectroscopy. The first approach, called Multivariate Curve Resolution with the Addition Method, combines the standard addition method with multivariate curve resolution. The second one uses a criterion based on reducing the spectrum complexity when a spectral component is removed from a Raman spectrum of a multi-component sample entirely. The results demonstrate the superiority of the first approach relative to the second for both small volume fraction of the fluid stain compared to the substrate and random noise.

Metabolomic profiling of human semen in patients with oligospermia using high performance liquid chromatography-tandem mass spectrometry.

Male infertility is one of the most common reproductive dysfunctions. Despite oligospermia being a cause of infertility, few studies have been conducted on it. This study aimed to investigate differences in semen metabolic patterns in patients with oligospermia and to identify potential biomarkers associated with oligospermia. Semen samples from oligospermia patients (20 cases) and healthy controls (20 cases) were detected by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), and 72 and 89 metabolites were identified as potential markers in positive and negative ion modes, respectively. In addition, the results identified multiple metabolic pathways in patients with oligospermia, such as glycine serine and threonine metabolism, Synthesis and degradation of ketone bodies, Valine, leucine, and isoleucine degradation. These results described unique metabolic characteristics of semen in patients with oligospermia and provided novel insights into the mechanism of the semen disorder.

Role of metformin in male oxidative stress infertility (MOSI): An in vitro experimental study.

The study aimed to determine the in-vitro effect of metformin on total antioxidant capacity (TAC) of seminal samples of infertile male subjects. It was conducted from January to June 2022 on forty-four seminal plasma samples collected from male infertile patients, age ranging from 18 to 55 years. All 44 semen samples were treated as three distinct groups: (i) a control group (ii) a study group subjected to oxidative stress (OS) induction and (iii) a test group exposed to OS induction and subsequent treatment with metformin. OS was introduced by using commercially available 100µM hydrogen peroxide (H2O2) and incubated for twenty-four hours at 37ºC. After that 1 ml of 100 mmol/l concentration of commercially available Metformin (PHR 1331, CAS: 461-58-5) was administered to test group samples for additional 24h at 37ºC. Low levels of TAC were observed after OS induction in comparison to the control group (p=0.01). In test samples (after treatment with Metformin), a positive correlation of TAC with sperm count, normal sperm morphology and sperm motility were observed however, results were not significant. The antioxidant effect of Metformin was shown to improve the antioxidant capacity of OS induced samples and their sperm parameters in seminal plasma of infertile male subjects.

A Comparison of White and Yellow Seminal Plasma Phosphoproteomes Obtained from Turkey (Meleagris gallopavo) Semen.

Seminal plasma is rich in proteins originating from various male reproductive organs. The phosphorylation of these proteins can significantly impact sperm motility, capacitation, and acrosome reaction. Phosphoproteomics identifies, catalogues, and characterizes phosphorylated proteins. The phosphoproteomic profiling of seminal plasma offers valuable insights into the molecular mechanisms that influence semen quality and male fertility. Thus, the aim of this study was a phosphoproteomic analysis of white and yellow turkey seminal plasma. The experimental material consisted of 100 ejaculates from BIG-6 turkeys between 39 and 42 weeks of age. The collected white and yellow turkey seminal plasmas were analyzed for total protein content; the activity of selected enzymes, i.e., alkaline phosphatase (ALP), acid phosphatase (ACP), superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT); and the content of reduced glutathione (GSH) and malondialdehyde (MDA). Phosphoproteins were isolated from white and yellow seminal fluids, and the resulting protein fractions were separated by SDS-PAGE and Western blotting. Phosphorylated residues were immunodetected, and the isolated phosphoproteins were identified (nano LC-MS/MS). Yellow seminal plasmas were characterized by higher levels of total protein, GSH, and MDA, as well as higher levels of ALP, ACP, and GPx activity. There were no significant differences in the activity of SOD and CAT. A total of 113 phosphoproteins were identified in turkey seminal fluids. The functional analysis demonstrated that these phosphoproteins were mainly involved in oocyte fertilization, organization and metabolism of the actin cytoskeleton, amplification of the intracellular signal transduction pathway, general regulation of transport, vesicular transport, proteome composition of individual cellular compartments, and the organization and localization of selected cellular components and macromolecules. Increased phosphorylation of the fractions containing proteins encoded by SPARC, PPIB, TRFE, QSOX1, PRDX1, PRDX6, and FASN genes in white plasmas and the proteins encoded by CKB, ORM2, APOA1, SSC5D, RAP1B, CDC42, FTH, and TTH genes in yellow plasmas was observed based on differences in the optical density of selected bands. The obtained results indicate that the phosphorylation profiles of turkey seminal plasma proteins vary depending on the type of ejaculate.

Exploratory Metabolomics and Lipidomics Profiling Contributes to Understanding How Curcumin Improves Quality of Goat Semen Stored at 16 °C in Tropical Areas.

Reactive oxygen species (ROS) exert a vital role in sperm quality during semen preservation, where excessive ROS leads to oxidative damage and undermines sperm integrity. Curcumin, a botanical extract, is capable of neutralizing ROS and enhancing the activity of antioxidant enzymes. This study was aimed at evaluating the effects of curcumin on sperm viability, acrosome integrity, and antioxidant levels, as well as metabolomic and lipidomic profiles. The results demonstrated that curcumin at 25 µmol/L significantly enhanced sperm motility, plasma membrane, and acrosome integrity, elevated the levels of antioxidant enzymes (T-AOC, CAT, SOD), and decreased ROS production (p < 0.05). Metabolomic analysis identified 93 distinct metabolites that showed significant differences between the control and curcumin-treated groups. KEGG pathways emphasized the participation of these metabolites in key metabolic processes such as the citric acid cycle, cholesterol metabolism, and fatty acid metabolism. Curcumin treatment brought about notable variations in lipid profiles, including increased levels of phosphatidylcholine, acylcarnitine, and triglyceride over the storage time, suggesting enhanced lipid anabolic activity. Overall, the supplementation of curcumin at 25 µmol/L effectively mitigates oxidative stress and prolongs the viability of semen storage at 16 °C by modulating specific metabolic and lipid profiles.

Reversible effects of the SARS-CoV-2 on semen parameters.

Despite that the SARS-CoV-2 pandemic has been controlled, it has affected a large proportion of the population, raising some concerns about potential sequelae in men at reproductive age. To contribute to the clarification of this issue, we performed a retrospective study comparing semen parameters values before and after confirmed SARS-CoV-2 infection in a large cohort of infertile men, compared to a control group that did not undergo SARS-CoV-2 infection. Wilcoxon test on paired samples and general linear regression model showed that SARS-CoV-2 infection has a detrimental effect on semen volume values (p < 0.005). However, semen volume seems to be significantly lower only during the first spermatogenic cycle after SARS-COV-2 infection (p < 0.005) and mainly in unvaccinated patients (p < 0.05). In addition, we detected alterations in progressive motility in patients infected with the alpha SARS-COV-2 strain (p < 0.05). In conclusion, our results show that although SARS-CoV-2 has a small effect on semen volume and sperm motility in infertile men, depending on the infectious strain or vaccination status, pre-infection values of semen parameters appear to be restored over one spermatogenic cycle after infection.

Impact of high-risk and low-risk human papillomavirus infections on the male genital tract: effects on semen inflammation and sperm quality.

Human Papillomavirus (HPV), a prevalent sexually transmitted infection, comprises high-risk (HR-HPV) and low-risk (LR-HPV) viruses, the former posing a high risk for developing malignancies whereas the latter mainly for benign warts. Despite increasing awareness of HPV's impact on men's health, the influence of HR-HPV and LR-HPV urogenital infections on male fertility potential remains uncertain. This study aimed to investigate whether male urogenital infection with HR- or LR-HPV associates with impaired sperm quality, oxidative stress, and inflammation. A total of 205 male patients attending an urology clinic were enrolled. Semen samples were analyzed for HPV using PCR and genotyped by RFLP. Semen quality was evaluated following WHO guidelines. Semen leukocytes, reactive oxygen species (ROS), and sperm viability were analyzed using flow cytometry. HPV was detected in 19% (39/205) of semen samples. HR-HPV infections were more prevalent, with HPV-16 being the most frequent genotype. Neither HR-HPV nor LR-HPV were associated with significant alterations in routine sperm quality parameters. However, HR-HPV+ individuals showed significantly higher levels of sperm necrosis and exhibited increased proportions of ROS+ spermatozoa compared to LR-HPV+ or control individuals. Furthermore, no significant semen inflammation was detected in patients infected with either HR-HPV or LR-HPV, and unexpectedly reduced semen leukocytes and inflammatory cytokines (IL-6 and IL-1ß) were observed in HR-HPV+ patients compared to controls. These observations underscore the importance of comprehensive HPV screening, including genotyping, in urology and fertility clinics to understand the progression of the infection, potential adverse effects on reproductive health, and the oncogenic risks involved.

Enhancing canine semen quality through a second centrifugation after 48 hours of storage: a comparative study.

BACKGROUND: Centrifugation is a common procedure to improve the quality of chilled and frozen canine semen by removing debris and seminal plasma and adding semen extenders. The aim of this study was to evaluate the efficacy and influence of a second centrifugation after 48 h of storage at 5 °C on the sperm quality of canine semen. The ejaculates of 45 healthy male dogs, divided into three groups according to body weight, were analyzed for macro- and microparameters such as ejaculate volume, sperm concentration, kinematic parameters, morphology, and integrity of plasma membrane. Samples were analyzed at baseline conditions (T0), after 24 h (T24) and after 48 h (T48) to assess the effects of the different treatments on sperm quality. RESULTS: The results showed a significant effect of a second centrifugation on the improvement of chilled sperm quality compared to the other techniques, especially up to 48 h. CONCLUSIONS: Analysis of the data showed that the semen samples centrifuged and then cooled at 5 °C had acceptable semen parameters, especially in terms of motility, with a gradual decrease in serial evaluations after 24 and 48 h. A second centrifugation after 48 h of storage may lead to better semen quality and improve the kinetics of sperm parameters, the percentage of morphologically normal sperm and the percentage of sperm with intact membranes.

Temporal effect of flaxseed oil in boar's diet on semen quality, antioxidant status and in-vivo fertility under hot humid sub-tropical condition.

The present study investigates the temporal effects of flaxseed supplementation on boar semen quality, antioxidant status, and in-vivo fertility under high-temperature humidity index (THI) conditions in a sub-tropical climate. Twelve Hampshire crossbreed boars were randomly assigned to control and treatment groups, with the treatment group receiving flaxseed oil supplementation. Semen samples were collected and analyzed for semen quality parameters, sperm kinematics, and antioxidant status. Fertility outcomes were assessed through in-vivo mating trials. Flaxseed supplementation resulted in time dependent significant improvements in semen volume, sperm concentration, total and progressive sperm motility, sperm quality parameters, and antioxidant status. Fertility outcomes, including farrowing rates and litter sizes, were also enhanced in the flaxseed-supplemented group. These findings highlight the potential of flaxseed supplementation to improve boar fertility under high ambient stress conditions, with implications for optimizing reproductive performance in swine production systems.

Effects of short-term oral letrozole on fresh semen parameters, endocrine balance, and prostate gland dimensions in domestic dogs.

BACKGROUND: Aromatase inhibitors improve male fertility by modifying the hormonal control of spermatogenesis. The present study aimed to investigate the effects of oral administration of letrozole on testosterone and estradiol concentrations and their ratios in blood serum, seminal plasma, prostatic fluid, sperm quality in fresh semen, and prostate gland dimensions. Seven adult male intact mixed-breed dogs were selected. The animals received letrozole (72 µg/kg, PO) daily for four weeks. Blood samplings and semen collections were carried out on days 0 (control), 14 (treatment), 28 (treatment), and 42 (post-treatment). RESULTS: Our results showed that letrozole administration resulted in a 4.3 fold significant increase in serum, seminal plasma, and prostatic fluid testosterone levels after 14 days. This remained high until the end of the study. Serum and prostatic fluid estradiol levels did not change significantly over the study period. However, the seminal plasma estradiol level showed a significant increase on day 14. The estradiol: testosterone ratio was significantly reduced on day 14 in serum, seminal plasma, and prostatic fluid samples. Letrozole significantly improved the ejaculated spermatozoa viability and concentration after 28 days of oral administration. However, the sperm plasma membrane functional integrity and kinematic parameters were not significantly affected by the treatment. Transabdominal ultrasound examination revealed a significant increase in the height, width, and volume of the prostate gland after 28 days of treatment. CONCLUSIONS: According to the present research, oral administration of letrozole for 28 days affects local and systemic sex hormone balance leading to an improvement of the ejaculated canine spermatozoa viability and concentration concurrent with an increase in the prostate gland dimensions.

Quality and kinematic characteristics of Bali bulls frozen semen with purified green tea extract epigallocatechin-3-gallate antioxidant addition in diluent.

Background: The preservation of semen quality and kinematic characteristics during cryopreservation is crucial for the reproductive success and genetic management of livestock, particularly in Bali bulls. Aim: This study aimed to investigate the effect of adding purified green tea extract antioxidant Epigallocatechin-3-gallate (EGCG) in tris egg yolk diluent on the quality and kinematic characteristics of frozen semen from Bali bulls. Methods: Fresh and frozen semen samples were obtained from Bali bull and divided into four different treatment groups. P0 contained semen samples + diluent, while P1 to P3 consisted of semen samples + diluent supplemented with EGCG levels of 0.1, 0.15, and 0.2 mg/100 ml, respectively. Data were analyzed using One-way ANOVA and followed by Duncan's test if significant differences were found (p<0.05). Parameters observed included the assessment of fresh semen quality, kinematic analysis, post-thawing sperm viability, and abnormality. Results: The results indicated that the assessment of fresh semen quality showed macroscopic and microscopic semen quality according to SNI 4869-1:2021. Kinematic analysis revealed significant differences in DSL and STR parameters between P0 and P3 (p<0.05). EGCG supplementation also caused significant differences in motility between P0 and P3 (p<0.05). Viability and spermatozoa abnormality with EGCG supplementation did not show significant differences (p>0.05). Conclusion: The best results for motility, kinematics, and sperm morphology variables were found in P1 as it did not exhibit a decrease in motility, kinematics, and sperm morphology. Viability did not show significant differences between P1, P2, and P3, but the best results were found in P2 as it did not exhibit a decrease in viability with mean and standard deviation (66.84 ± 7.88). Abnormality variables also did not show significant differences between P1, P2, and P3, but the best results were found in P2 as it did not exhibit a decrease in abnormality with mean and standard deviation (23.80 ± 7.36).

SARS-CoV-2 impairs male fertility by targeting semen quality and testosterone level: A systematic review and meta-analysis.

BACKGROUND: Since the discovery of COVID-19 in December 2019, the novel virus has spread globally causing significant medical and socio-economic burden. Although the pandemic has been curtailed, the virus and its attendant complication live on. A major global concern is its adverse impact on male fertility. AIM: This study was aimed to give an up to date and robust data regarding the effect of COVID-19 on semen variables and male reproductive hormones. MATERIALS AND METHODS: Literature search was performed according to the recommendations of PRISMA. Out of the 852 studies collected, only 40 were eligible for inclusion in assessing the effect SARS-CoV-2 exerts on semen quality and androgens. More so, a SWOT analysis was conducted. RESULTS: The present study demonstrated that SARS-CoV-2 significantly reduced ejaculate volume, sperm count, concentration, viability, normal morphology, and total and progressive motility. Furthermore, SARS-CoV-2 led to a reduction in circulating testosterone level, but a rise in oestrogen, prolactin, and luteinizing hormone levels. These findings were associated with a decline in testosterone/luteinizing hormone ratio. CONCLUSIONS: The current study provides compelling evidence that SARS-CoV-2 may lower male fertility by reducing semen quality through a hormone-dependent mechanism; reduction in testosterone level and increase in oestrogen and prolactin levels.

Paternal undernutrition and overnutrition modify semen composition and preimplantation embryo developmental kinetics in mice.

BACKGROUND: The importance of parental diet in relation to eventual offspring health is increasing in prominence due to the increased frequency of parents of reproductive age consuming poor diets. Whilst maternal health and offspring outcome have been studied in some detail, the paternal impacts are not as well understood. A father's poor nutritional status has been shown to have negative consequences on foetal growth and development and ultimately impact the long-term adult health of the offspring. In this study, we examined sperm- and seminal vesicle fluid-mediated mechanisms of preimplantation embryo development alterations in response to sub-optimal paternal diets. RESULTS: Male mice were fed a diet to model either under (low-protein diet (LPD)) or over (high-fat/sugar 'Western' diet (WD)) nutrition, LPD or WD supplemented with methyl donors or a control diet (CD) before mating with age-matched females. Male metabolic health was influenced by WD and MD-WD, with significant changes in multiple serum lipid classes and hepatic 1-carbon metabolites. Sperm RNA sequencing revealed significant changes to mRNA profiles in all groups when compared to CD (LPD: 32, MD-LPD: 17, WD: 53, MD-WD: 35 transcripts). Separate analysis of the seminal vesicle fluid proteome revealed a significant number of differentially expressed proteins in all groups (LPD: 13, MD-LPD: 27, WD: 24, MD-WD: 19) when compared to control. Following mating, in vitro time-lapse imaging of preimplantation embryos revealed a significant increase in the timing of development in all experimental groups when compared to CD embryos. Finally, qPCR analysis of uterine tissue at the time of implantation identified perturbed expression of Cd14 and Ptgs1 following mating with WD-fed males. CONCLUSIONS: Our current study shows that paternal nutritional status has the potential to influence male metabolic and reproductive health, impacting on embryonic development and the maternal reproductive tract. This study highlights potential direct (sperm-mediated) and indirect (seminal vesicle fluid-mediated) pathways in which a father's poor diet could shape the long-term health of his offspring.

Seminal plasma inhibits Chlamydia trachomatis infection in vitro, and may have consequences on mucosal immunity.

Seminal plasma (SP) is the main vector of C. trachomatis (CT) during heterosexual transmission from male to female. It has immunomodulatory properties and impacts the susceptibility to HIV-1 infection, but its role has not been explored during CT infection. In the female reproductive tract (FRT), CT infection induces cytokine production and neutrophil recruitment. The role of neutrophils during CT infection is partially described, they could be at the origin of the pathology observed during CT infection. During this study, we developed an experimental in vitro model to characterize the impact of CT infection and SP on endocervical epithelial cell immune response in the FRT. We also studied the impact of the epithelial cell response on neutrophil phenotype and functions. We showed that the production by epithelial cells of pro-inflammatory cytokines increased during CT infection. Moreover, the pool of SP as well as individuals SP inhibited CT infection in a dose-dependent manner. The pool of SP inhibited cytokine production in a dose-dependent manner. The pool of SP altered gene expression profiles of infected cells. The culture supernatants of cells infected or not with CT, in presence or not of the pool of SP, had an impact on neutrophil phenotype and functions: they affected markers of neutrophil maturation, activation and adhesion capacity, as well as the survival, ROS production and phagocytosis ability. This study proposes a novel approach to study the impact of the environment on the phenotype and functions of neutrophils in the FRT. It highlights the impact of the factors of the FRT environment, in particular SP and CT infection, on the mucosal inflammation and the need to take into account the SP component while studying sexually transmitted infections during heterosexual transmission from male to female.

Evaluation of Known Markers of Ferroptosis in Semen of Patients with Different Reproductive Pathologies and Fertile Men.

This study aims to investigate the role of ferroptosis, an iron-dependent form of regulated cell death, in male infertility. The motivation behind this research stems from the increasing recognition of oxidative stress and iron metabolism dysregulation as critical factors in male reproductive health. In this study, 28 infertile patients (grouped by the presence of urogenital infections or varicocele) and 19 fertile men were selected. Spermiograms were performed by light microscopy (WHO, 2021). Testosterone, ferritin, transferrin-bound iron, transferrin, and F2-isoprostanes (F2-IsoPs) were detected in seminal plasma. Glutathione peroxidase 4 (GPX4) and acyl coenzyme A synthetase long chain family member 4 (ACSL4) were also assessed in sperm cells using enzyme-linked immunosorbent assays (ELISA). All the variables were correlated (statistically significant Spearman's rank correlations) in the whole population, and then the comparison between variables of the different groups of men were carried out. Seminal ferritin and transferrin positively correlated with seminal F2-IsoPs, which had positive correlations with ACSL4 detected in sperm cells. Ferritin and ACSL4 negatively correlated with the seminal parameters. No correlation was detected for GPX4. Comparing the variables in the three examined groups, elevated levels of ACSL4 were observed in infertile patients with urogenital infections and varicocele; GPX4 levels were similar in the three groups. These results suggested a mechanism of ferroptosis, identified by increased ACSL4 levels and the occurrence of lipid peroxidation. Such events appear to be GPX4-independent in reproductive pathologies such as varicocele and urogenital infections.

Trends and challenges in liquid-preserved boar semen production: From boar to product.

Boar semen production plays a pivotal role in modern swine breeding programmes, influencing the genetic progress and overall efficiency of the pork industry. This review explores the current challenges and emerging trends in liquid-preserved boar semen production, addressing key issues that impact the quality and quantity of boar semen. Advances in new reproductive technologies, boar selection, housing, semen processing, storage and transport, and the need for sustainable practices including the use of artificial intelligence are discussed to provide a comprehensive overview of the field.

The quality and characteristics of bovine sperm are compromised by Toxoplasma gondii antigens, impacting in in vitro bull fertility.

Studies in various species have demonstrated different results on the effects of T. gondii infection on sperm quality. It has also been demonstrated that in some stages of the disease, there is elimination of cellular debris or even the intact parasite in the semen. The present work aimed to evaluate the in vitro effects of the presence of soluble T. gondii antigens in bovine semen on sperm integrity. The spermatozoa were treated with T. gondii antigens in double serial dilutions classified as high, medium and low doses (8, 4, 2 µg/ml) in "TALP-Sperm" and "TALP-Fert" media. The results showed that T. gondii antigens affect sperm motility and mitochondrial activity, and cause changes in sperm chromatin integrity, as well as damage to the sperm membrane and acrosome. Finally, spermatozoa treated with T. gondii antigens were evaluated in the in vitro production of embryos (IVEP). The use of semen contaminated with antigens in IVEP routines did not lead to a decrease in the fertilization of oocytes, as sperm undergo selection before in vitro fertilization, which eliminates the most altered sperm. However, early embryonic development was affected, probably by structural changes that were not eliminated in the selection process. The results demonstrated that the presence of soluble T. gondii antigens in bovine semen alters sperm integrity and vital characteristics for the fertilization process and embryonic development and therefore causes fertility problems in males.

Effect of heat stress on semen characteristics and genetics in Thai native grandparent roosters.

Grandparent roosters are crucial in poultry breeding programs and significantly influence future bird generations' genetic makeup and performance. However, these roosters face considerable challenges from heat stress, which can adversely affect their reproductive performance, semen quality, and overall health and welfare. Our study aimed to investigate the effects of heat stress on the genetics of semen characteristics, identify the appropriate temperature and humidity indices (THI), and determine the threshold point of heat stress to prevent thermal stress. We analyzed data from 3,895 records of 242 Thai native grandparent roosters in conjunction with the THI using 7 THI functions and the regression method. The threshold point of heat stress, genetic parameters, rate of decline of semen characteristics per level of THI, estimated breeding values and selection index values were analyzed using the multivariate test-day model in the AIREML and BLUPF90 programs. Based on the regression coefficient and statistical criteria of the lowest -2logL and AIC values, the results showed that a THI of 78 was considered the threshold point of heat stress. The estimated heritability values ranged from 0.023 to 0.032, 0.066 to 0.069, 0.047 to 0.057, and 0.022 to 0.024 for mass movement, semen volume, sperm concentration, and the semen index, respectively. The reduction rates of mass movement, semen volume, sperm concentration, and semen index at a THI of 78 were -0.009, -0.003, -0.170, and -0.083 per THI, respectively. The genetic correlations among the semen traits were moderately to strongly positive and ranged from 0.562 to 0.797. The genetic correlations between semen traits and heat stress were negative and ranged from -0.437 to -0.749. The permanent environmental correlations among the semen traits (0.648-0.929) were positive and greater than the genetic correlations. Permanent environmental correlations between semen traits and heat stress were negative and ranged from -0.539 to -0.773. The results of the selection indices showed that the higher the selection intensity was, the greater the degree to which the selection index corresponded to genetic progress. The recommendation for animal genetic selection is that the top 10% is appropriate because it seems most preferred. Therefore, using a multivariate test-day model and selection index for the high genetic potential of semen traits and heat tolerance in Thai native grandparent roosters makes it possible to achieve genetic assessment in a large population.