Conventional Semen Research Articles

Effects of herd fertility on the economics of sexed semen in a high-producing, pasture-based dairy production system

This study used a stochastic simulation model to estimate the potential economic benefit of using sexed semen in heifers only and in heifers and lactating cows in a high-producing, pasture-based system under 3 fertility scenarios. Three breeding strategies were modeled: (1) only heifers inseminated with sexed semen and cows inseminated with conventional unsexed semen (SSH); (2) both heifers and cows inseminated with sexed semen (SSHC); and (3) a reference scenario in which all females were inseminated with conventional, unsexed semen (CONV). Each scenario was evaluated under 3 herd fertility states: high (HF), medium (MF), and low (LF), which, under the reference scenario, corresponded to herd replacement rates of 21, 25, and 31%, respectively. The model estimated the economic profit, including the net present value of the genetic gain from selection intensity. The economic return from adoption of sexed semen strategies declined, with reduced levels of baseline herd fertility turning negative in the LF state. The mean (±SD) sexed semen advantage (SSA) per cow for HF-SSH, MF-SSH, and LF-SSH scenarios were €30.61 ± 8.98, €27.45 ± 7.19, and €14.69 ± 11.06, respectively. However, the SSA per cow for HF-SSHC, MF-SSHC, and LF-SSHC scenarios were €49.14 ± 15.43, €18.46 ± 30.08, and -€19.30 ± 57.11. The range in economic profit for SSA for SSH was most sensitive to calf prices in HF-SSH and the pregnancy rate of sexed semen as a percentage of conventional unsorted semen in MF-SSH and LF-SSH. The range in economic profit for SSA for SSHC scenarios was most sensitive to the pregnancy rate of sexed semen as a percentage of conventional unsorted semen in HF-SSHC, MF-SSHC, and LF-SSHC. This study highlights the effect of baseline herd fertility state on the financial advantage of adopting sexed semen in a pasture-based dairy production system.

The micro-RNA content of unsorted cryopreserved bovine sperm and its relation to the fertility of sperm after sex-sorting

BackgroundThe use of sex-sorted sperm in cattle assisted reproduction is constantly increasing. However, sperm fertility can substantially differ between unsorted (conventional) and sex-sorted semen batches of the same sire. Sperm microRNAs (miRNA) have been suggested as promising biomarkers of bull fertility the last years. In this study, we hypothesized that the miRNA profile of cryopreserved conventional sperm is related to bull fertility after artificial insemination with X-bearing sperm. For this purpose, we analyzed the miRNA profile of 18 conventional sperm samples obtained from nine high- (HF) and nine low-fertility (LF) bulls that were contemporaneously used to produce conventional and sex-sorted semen batches. The annual 56-day non-return rate for each semen type (NRRconv and NRRss, respectively) was recorded for each bull.ResultsIn total, 85 miRNAs were detected. MiR-34b-3p and miR-100-5p were the two most highly expressed miRNAs with their relative abundance reaching 30% in total. MiR-10a-5p and miR-9-5p were differentially expressed in LF and HF samples (false discovery rate < 10%). The expression levels of miR-9-5p, miR-34c, miR-423-5p, miR-449a, miR-5193-5p, miR-1246, miR-2483-5p, miR-92a, miR-21–5p were significantly correlated to NRRss but not to NRRconv. Based on robust regression analysis, miR-34c, miR-7859 and miR-342 showed the highest contribution to the prediction of NRRss.ConclusionsA set of miRNAs detected in conventionally produced semen batches were linked to the fertilizing potential of bovine sperm after sex-sorting. These miRNAs should be further evaluated as potential biomarkers of a sire’s suitability for the production of sex-sorted sperm.

Time intervals between semen production, initiation of analysis, and IUI significantly influence clinical pregnancies and live births.

Does IDEF mapping help monitor the technical process of IUI and explore the potential improvements which might contribute to increased pregnancy and live birth rates? Retrospective analysis of 1729 homologous IUI cycles of couples attending a fertility clinic in a university hospital setting. Standardized conventional semen parameters were analyzed and the semen samples prepared via discontinuous density gradient centrifugation. There was no significant association between sperm concentration, motility and morphology (analysis phase), and pregnancy outcome. Only female and male ages were significantly associated with the pregnancy outcome. There was a significant difference in the odds on clinical pregnancies and live births when analysis was ≤ 21min initiated, and < 107min between sample production and IUI, adjusted for male and female age. Adjusting for the couple's age, we could show that time intervals between semen production and analysis and IUI when kept low significantly influenced clinical pregnancies and live births.

50 Sex ratio at birth in dairy cattle is affected by the invitro embryo production process

Data from a herd of 3,000 high-producing milking dairy cows under an intensive feeding system was analysed. The IVF laboratory at the farm uses a co-culture system (Vivanco-Mackie; page 30-48 in Proc. 2000 Australian Embryo Transfer Society) and transfers ∼1000 embryos per year. The semen used for IVF and for inseminations (AI) in the herd was female-sexed (F-sexed) and non-sexed (conventional). During the 4 years of evaluation (2016–2019) 1123 calves were born to AI with F-sexed semen and 6,456 to AI with conventional semen; the proportion of males born to AI with F-sexed semen was 9% (91% females), which was not different (P&amp;gt;0.05) from the expected ratio of 10% males and 90% females. The proportion of male calves born to AI with conventional semen was 53.2% (46.8% females), which agrees with the expected ratios for the population. During the same period of evaluation, 805 calves were born to IVF embryos transferred; 240 calves were born from embryos produced using F-sexed semen, of which 29.6% were males and 70.4% females, which was different (P&amp;lt;0.05) from the expected ratio of 10% males and 90% females. The proportion of male calves born from embryo transfer of IVF embryos produced with conventional semen was 82.7%, higher (P&amp;lt;0.05) than the expected 53.2% of males for the population; the proportion of females was 17.3%, significantly lower (P&amp;lt;0.05) than the expected 46.8% females for the population. For IVF, the proportion of males was significantly higher (P&amp;lt;0.05) than expected in all cases; for AI, there was no difference (P&amp;gt;0.05) between the observed sex proportion and the expected values. We conclude that the invitro embryo production process affects the sex ratio at birth in this population, and some factor in the IVF process is affecting the survival to calving of female embryos and consequently increasing the proportion of male calves born from invitro-produced embryos. Gutierrez et al. (2001 Reprod. Fertil. Dev. 13, 361–365) found a similar effect in dairy cattle and linked it to glucose imbalance in the media. Larson et al. (2001 PNAS 98, 9677-9682) found that female cattle embryos had a lower ability to progress in development in glucose-rich media, but the mechanism is not yet fully understood. Xu et al. (1992Mol. Reprod. Dev. 31, 249-252) and others indicate that invitro-produced male bovine embryos predominate among blastocysts, expanded and hatched stages. Meanwhile, embryos lagging in development are predominantly female. Kun Tan et al. (2016 Reproduction 151, 443-543) found that IVF in mice favours the birth of males because of dysregulated expression of representative dimorphic genes. Further studies in cattle are necessary to determine the cause of the increased proportion of males born from invitro embryos and to find ways to control it.

51 Comparison of SexedULTRA 4M and conventional semen for invitro production of bovine embryos using two bulls

SexedULTRA 4M™ (Select Sires) is made using an improved method of sex-sorting sperm in a less damaging environment for retaining sperm integrity through the sorting process. The combination of invitro embryo production (IVP) and sexed semen technologies has been successful for intensity selection in the cattle industry. The objective of this research was to compare conventional (CONV) and SexedULTRA 4M (ULTRA-4M) semen for bovine IVP using 2 bulls. The research was carried out in the reproduction laboratory at Palominos Ranch (Jalisco, México). The IVP was performed with a continuous invitro culture system. Ovaries from commercial cattle (n=213) were collected from a slaughterhouse (León, México) and transported to the laboratory within 2h in physiological saline solution (0.9% NaCl) supplemented with penicillin G (100IUmL−1) and streptomycin sulphate (100µg mL−1). For IVP, IVF Bioscience™ media were used for IVM, IVF, and invitro culture (IVC). For the IVM, the cumulus–oocyte complexes (COCs) were selected (grades 1 and 2) and matured for 24h at 38.5°C in 5% CO2 in air and 100% humidity. Matured oocytes (n=1200, divided equally into 3 replicates) were divided into 2 groups, the CONV group and the ULTRA-4M group. The IVF process was conducted with both CONV and ULTRA-4M semen from the 2 bulls, separately, at an adjusted concentration of 2×106 and 0.5×106 sperm mL−1, respectively, for 18h in 38.5°C, 5% CO2 in air, and 100% humidity. The presumptive zygotes were denuded by pipetting and set in IVC until Day 7 at 38.5°C, 5% CO2, 5% O2 and 90% N2 at 100% humidity. The cleavage rate, embryos with more than 6 cells, and blastocysts on Day 7 of culture were evaluated. Statistical analysis was carried out with the GLM procedure of SAS (version 9.3; SAS Institute Inc.) to evaluate the results of CONV versus ULTRA-4M for each bull (α level=0.05). Cleavage rates were 57.1%±1.5 and 59.4%±1.5, respectively in CONV and ULTRA-4M groups with Bull 1 and 43.3%±1.5 and 45.2%±1.5 with Bull 2. The percentages of embryos with more than 6 cells were 51.4%±1.0 and 53.9%±1.0, respectively, with CONV and ULTRA-4M with Bull 1 and 30.4%±1.0 and 33.4%±1.0 with Bull 2. The percentage of blastocysts on Day 7 with Bull 1 was 34.4%±1.7 for CONV and 36.2%±1.7 for ULTRA-4M; for Bull 2, the results were 26.5%±1.7 for CONV and 29.5%±1.7 for ULTRA-4M. There were no significant differences between the CONV and ULTRA-4M groups (P&amp;gt;0.05) for all variables analysed for each bull; however, Bull 1 was significantly superior to Bull 2 for all variables analysed. In conclusion, under the conditions of this research, ULTRA-4M and CONV semen produced similar bovine IVP results.

Sperm Motility is the Best Semen Parameter to Predict Sperm DNA Fragmentation

Purpose: Sperm DNA fragmentation (SDF) is associated with male infertility and abnormal semen parameters. However, the effect of SDF on each parameter may differ. In this study, we evaluated the correlation between different semen parameters and SDF to identify the most suitable predictor for abnormal SDF. Materials and Methods: We conducted a retrospective review from a prospective database. Enrollees who underwent conventional semen analysis and an SDF test for medical purposes or elective examinations were enrolled. SDF ≥20% was regarded as abnormal. Spearman correlation coefficient was used to determine the correlations. Area under the receiver operating characteristic curve area under the curve (AUC) was calculated to determine the predictive value. Youden index was used to determine the optimal cutoff value of conventional semen parameters to predict abnormal SDF. Results: In total, 90 men were enrolled, of whom 44 (48.89%) visited for infertility and 51 (56.67%) had abnormal semen analysis. Immotile sperm (IM) and nonprogressive sperm (NPS, NPS = nonprogressive motility + IM) were significantly correlated with SDF (r = 0.50, P&lt; 0.001 for NPS; r = 0.49, P&lt; 0.001 for IM) and were the most predictive for abnormal SDF (AUC = 0.77 for NPS; AUC = 0.78 for IM). By using Youden index, the cutoff values for the prediction of abnormal SDF were 66.37% for NPS and 48.73% for IM. Conclusion: Sperm motility is the most predictive and relevant parameter for the prediction of abnormal SDF. Suboptimal sperm motility should be considered an indication for SDF testing.

Advanced Paternal Age and Sperm DNA Fragmentation: A Systematic Review.

PurposeMale ageing is often associated with defective sperm DNA remodeling mechanisms that result in poorly packaged chromatin and a decreased ability to repair DNA strand breaks. However, the impact of advanced paternal age on DNA fragmentation remains inconclusive. The aim of the present systematic review was to investigate the impact of advancing paternal age (APA) on DNA fragmentation.Materials and MethodsWe conducted a thorough search of listed publications in Scopus, PubMed, and EMBASE, in accordance with the PRISMA guidelines.ResultsWe identified 3,120 articles, of which nineteen were selected for qualitative analysis, resulting in a sample of 40,668 men. Of the 19 articles evaluating the impact of APA on DFI% (DNA fragmentation Index) included, 4 were on Normozoospermic and subfertile men, 3 on normozoospermic, Oligoasthenoteratozoospermic and Teratozoospermic, 6 on fertile and infertile men, 4 on just infertile men, and 2 evaluated a general population. Seventeen of the ninrnteen studies demonstrated APA's effect and impact on DFI%.ConclusionsAlthough there was no universal definition for APA, the present review suggests that older age is associated with increased DFI. In elderly men with normal semen parameters, further studies should be performed to assess the clinical implications of DFI, as a conventional semen analysis can often fail to detect an etiology for infertility.

A prospective study of variations in conventional semen parameters among local andrology laboratories

Introduction: Wide variations in semen parameters exist among different andrology laboratories. This study sought to determine the inter- and intra-technician variations in conventional semen parameters among local andrology laboratories. Methods: Pooled semen samples were prepared and sent in two batches to participating andrology laboratories. One technician who routinely performed semen analysis in the participating laboratories was asked to analyze the study samples. The inter-technician and intra-technician coefficients of variation (CVs) were calculated. Information on the qualification and training of the participating technicians, the workload of the centers, their techniques and participation in external quality assurance programs were collected and correlated with the CVs. Results: Eleven andrology laboratories participated in the study. The inter-technician CVs ranged from 14.3% to 44.1% for concentration, 13.8% to 26.2% for progressive motility, and 38.8% to 95.3% for morphology. Andrology laboratories which participated in external quality assurance programs had lower inter-technician CVs for concentration (P = 0.004) and progressive motility (P = 0.002), but not for morphology (P = 0.232). Technicians with more experience or higher workload did not demonstrate lower intra-technician CVs. Conclusion: There were considerable inter- and intra- technician variations in the assessment of sperm concentration, progressive motility and morphology among local andrology laboratories, independent of the workload and experience of the technicians. Participation in external quality assurance programs reduced inter-technician variations in sperm concentration and progressive motility but not morphology.

Fertility Outcomes After Varicocele Repair: Are There Any Benefits? A Traditional Review

Backgrounds: A varicocele is identified in 15% of healthy men and around 40% of men with primary infertility suffer from some degree of varicocele. The presence of spermatic varicose veins creates a hostile environment for spermatogenesis. It results in reduced quality and quantity of sperm production and, in some cases, can conduce to a total absence of sperm. This is due to an increase in circulating reactive oxygen species (ROS) resulting in sperm DNA fragmentation, even if the conventional semen parameters are within the normal reference ranges. It has been proposed that treating the varicocele may result in improvements in the semen parameters, fertilization, and pregnancy rates. Additionally, treating the varicocele could improve the results of both spontaneous pregnancies as well as following in vitro fertilization (IVF), intracytoplasmic sperm injection (ICSI), and Assisted Reproduction Treatment (ART) in the presence of suboptimal semen parameters.

99 Increased expression of microRNAs in sperm of Nelore Bulls with high invitro fertility

The spermatozoon is no longer known only as a cell that delivers the male genetic material to the oocyte, because it also provides molecules such as microRNAs (miRNAs) that play a significant role in fertilization and embryonic development. MiRNAs are small noncoding RNAs capable of modulating mRNA translation, thus affecting important biological processes. Sperm miRNAs may influence embryo development and therefore, might be related to invitro production of embryos (IVP), considering that individual bulls have different fertility rates when used for IVF. The aim of this work was to identify miRNAs expressed in semen of bulls with high and low IVP rates. The composition of groups was based on a retrospective database from a reproductive biotechnology company between the years of 2016 and 2018, generating around 7000 IVP manipulations of 430 Nelore bulls. We only considered IVP manipulations that used a minimum of 30 oocytes and conventional semen selection by Percoll gradient. A total of 87 Nelore bulls fit these criteria. We then ranked bulls based on cleavage rate (number of cleaved structures/number of oocytes), blastocyst rate (number of blastocysts/number of oocytes) and embryo development rate (number of blastocysts/number of cleaved structures). Considering these three rates, we allocated bulls to two groups. The top eight were considered to have high IVP fertility (HF) and the bottom eight were grouped together as low IVP fertility (LF). We performed the T TEST procedure (SAS 9.3 software; SAS Institute Inc.) to compare the groups for cleavage (P&amp;lt;0.0001), blastocyst (P=0.0006), and embryo development (P=0.0001) rates. For miRNA analysis, sperm were separated using Percoll gradient and subjected to RNA extraction and cDNA synthesis. First, quantitative real-time PCR was used to evaluate the abundance of 380 bovine-specific miRNAs in a pool of samples for each group, using QuantStudio 6Flex. Then, 48 miRNAs presenting at least a 3-fold change of normalized cycle threshold values between groups were selected: 23 highly detected in HF, 1 highly detected in LF, 18 exclusively detected in HF, and 2 exclusively detected in LF. Last, we evaluated the abundance of these selected miRNAs in each experimental unit. We identified four miRNAs highly abundant in sperm from HF bulls, bta-miR-10a, bta-miR-383, bta-miR-93, and bta-miR-449b. Our results suggest that these miRNAs could play important roles in bovine embryo development. This work was supported by FAPESP (grant# 2018/03871-6).

Highly Cited Articles in the Field of Male Infertility and Antioxidants: A Scientometric Analysis.

PurposeThe objective of this scientometric analysis was to recognize the top 100 cited articles on ‘Male infertility and Antioxidants’ and analyze its publication characteristics.Materials and MethodsThe Scopus database was used to retrieve related articles and the top 100 identified based on citation rate.ResultsThe articles were published in 56 journals between 1995 and 2019 with a median (interquartile range) citation score of 17 (5–62). Among the top 100 articles, 69 were clinical studies, which included controlled and blinded (33.33%), prospective (27.54%), randomized-controlled trials (26.09%), uncontrolled (11.59%), and retrospective (1.45%) studies. In addition to conventional semen parameters, advanced sperm function tests such as oxidative stress (51%) and sperm DNA damage (23%) were reported. Pregnancy rate (33%) was found to be the most reported reproductive outcome. Antioxidant therapy was mostly investigated in male cohorts with sperm abnormalities such as asthenozoospermia (28%) and clinical conditions such as idiopathic male infertility (20%), varicocele/varicocelectomy (17%) and general male infertility (16%).ConclusionsThe most influential publications on antioxidants and male infertility were identified for the first time in the literature. This will serve as a reliable source of information for researchers and clinicians alike.

Purebreeding with sexed semen and crossbreeding with semen from double-muscled sires to improve beef production from dairy herds: Live and slaughter performances of crossbred calves

The use of sexed semen to produce purebred replacement heifers allows a large proportion of dairy cows to be mated to beef sires, and quantitative and qualitative improvements to be made to beef production from dairy herds. The major dairy and beef breeds are undergoing rapid genetic improvement as a result of more efficient selection methods, prompting a need to evaluate the meat production of crossbred beef × dairy cattle produced using current genetics. As part of a large project involving 125 commercial dairy farms, we evaluated the combined use of purebreeding with sexed semen and crossbreeding with semen from beef sires, particularly double-muscled breeds. A survey of 1,530 crossbred calves revealed that, whereas purebred dairy calves are destined almost exclusively for veal production, beef × dairy crossbred calves are also destined for beef production after fattening on either the dairy farm of birth or by specialized fatteners. In veal production, compared with Belgian Blue-sired calves (taken as the reference), double-muscled INRA 95-sired calves had a lighter slaughter weight (303 vs. 346 kg), but a greater dressing percent (62.3 vs. 58.4%). Limousin (also known as Limousine)-sired calves had a smaller average daily gain (1.26 vs. 1.34 kg/d), and lighter slaughter (314 vs. 346 kg) and carcass weights (182 vs. 201 kg). Last, Simmental-sired calves had a similar growth rate, but lighter carcass weight (177 vs. 201 kg), smaller dressing percentage (55.3 vs. 58.4%), and smaller muscularity scores (3.25 vs. 3.72). In the case of young bulls and heifers fattened on the dairy farm of birth, Belgian Blue-, Piemontese (also known as Piedmontese)-, and Limousin-sired calves performed similarly; the only exception was that Piemontese-sired calves had a greater dressing percentage. Belgian Blue- and Limousin-sired calves performed similarly when fattened by specialized beef producers. In both veal and beef production, the effects of dam breed were less important than sire breed. Considering the entire project, we can conclude that the combined use of sexed semen for purebreeding and conventional beef semen for terminal crossbreeding improves meat production from dairy herds, especially when the sires are double-muscled beef breeds.

Evaluation of biological and economic efficiency of the All Heifer, No Cow beef production system using a system dynamics model based on 6 yr of demonstration herd data.

Alternative management strategies with no cows and all heifers may improve biological and economic efficiency of beef production. The All Heifer, No Cow (AHNC) beef production system involves insemination of nulliparous heifers with female sex-selected semen (FSS) to produce primarily female calves that are early weaned at 3 mo of age. Dams are finished on a high concentrate diet and harvested before 30 mo of age. The objectives of this research were to: 1) build a dynamic model of an AHNC beef production system to quantify system biological and economic efficiency; 2) compare effects of utilizing FSS vs. conventional semen on biological and economic efficiency; 3) evaluate what-if scenarios to determine the effects on biological and economic efficiency of changing variables ±5%, 10%, 15%, and 20% from initial observed values; and 4) evaluate the effects on biological and economic efficiency of changing variables ±10% from initial observed values. A model was built over a 21-yr horizon using Stella Architect. Biological parameter values in the model were based on the 6 yr of data collected from the management of an AHNC demonstration herd. In the model animal, total digestible nutrients (TDN) intake, hot carcass weight (HCW), and age at harvest were randomized. Feed, animal, and carcass prices included in the model were based on 10 yr of historical U.S. price data. Key response variables were biological and economic efficiency (mean ± SD). Biological efficiency was defined as the ratio of output (kilograms of HCW produced) to input (lifetime kilograms of feed TDN consumed), and economic efficiency was measured using a benefit-cost ratio (BCR) and unit variable cost (UVC). Over 40 simulation runs, the predicted mean biological efficiency was 0.0714 ± 0.0008. Economic efficiency was 0.95 ± 0.02 and US $445.41 ± 0.06 for BCR and UVC, respectively. Biological and economic efficiency was improved in the conventional semen scenario; biological efficiency was 0.0738 ± 0.0008, and BCR and UVC were 0.99 ± 0.04 and US $407.24 ± 0.006, respectively. Under this parameterization and market conditions, the AHNC beef production system failed to achieve profitability under any scenario that was evaluated. However, this review did not account for the potential increased genetic benefit from a decreased generation interval and the reduction in feed energy in comparison to a conventional cow/calf system.

Reproductive parameters of Bos taurus and Bos indicus bulls during different seasons in tropical conditions: focus on an alternative approach to testicular assessments using ultrasonography

The aim of the present study was to evaluate the reproductive status of Bos taurus and Bos indicus bulls during different seasons when bulls were in a tropical environment focusing on systematic assessment of the testes using B-mode ultrasonography and ImageJ software to evaluate the testicular parenchymal tissues. The experimental design is a 2 × 2 factorial arrangement, with breed (Bos Taurus – Simmental; Bos indicus - Nellore) and season (summer; winter) as factors. Testicular ultrasonic evaluation and conventional semen analysis were performed. The Simmental bulls had more major sperm defects than Nellore bulls in the summer (P = 0.0001). Additionally, Simmental bulls had a greater percentage of major sperm defects during the summer than winter months P = 0.045). Furthermore, Nellore bulls had a greater testicular parenchyma echogenicity, with a greater grayscale, (caudal parenchyma, P = 0.0155; cranial parenchyma, P = 0.001) and mediastinum grayscale than Simmental bulls (Nellore = 52.32 ± 03.60; Simmental = 35.72 ± 03.67; P = 0.003). Simmental bulls also had a greater testicular lesion area (P = 0.0147). Results indicated there was susceptibility to heat stress when Simmental bulls were maintained in tropical regions. The results of the present study indicate there is an association between results when there was use of conventional andrological evaluation procedures and results from ultrasonic analysis using ImageJ software that allows for earlier identification of tissue aberrations that could lead to impaired semen quality and fertility.

147 Presynchronization and delayed fixed-time artificial insemination increases pregnancy rates with sex-sorted semen in replacement beef heifers

Abstract To determine effects of presynchronization and delayed fixed-time artificial insemination (TAI) on pregnancy rates to TAI (PR/AI) with sex-sorted semen, 2,855 Bos taurus beef heifers were enrolled in a completely randomized design. Within location, heifers were randomly assigned to one of eight treatments: 1 and 2), heifers were exposed to the 7-d CO-Synch+CIDR protocol wherein they received gonadotropin-releasing hormone (GnRH) and a CIDR insert on d 0, prostaglandin F2α (PGF) upon CIDR removal on d 7, and were TAI 54 ± 2 h later with conventional (CTRL54-CNV; n = 359) or sex-sorted semen (CTRL54-SEX; n = 356); 3 and 4), same as CTRL54 but were TAI at 72 ± 2 h with conventional (CTRL72-CNV; n = 366) or sex-sorted semen (CTRL72-SEX; n = 360); 5 and 6), same as CTRL54 but also received PGF 7 d prior to initial injection of GnRH (d -7) and were TAI with conventional (PRE54-CNV; n = 355) or sex-sorted semen (PRE54-SEX; n = 353); 7 and 8), same as PRE54 but had TAI delayed to 72 ± 2 h and were inseminated with conventional (PRE72-CNV; n = 351) or sex-sorted semen (PRE72-SEX; n = 355). All heifers received estrus detection patches on d 7, which were evaluated for activation at TAI. Ultrasonography was performed 30–45 d after TAI to determine PR/AI. Estrus expression was greater (P &amp;lt; 0.01) in the CTRL72 heifers compared to CTRL54, PRE54, and PRE72 heifers (73.0 vs 55.4, 43.4, and 65.7%, respectively). Moreover, estrus expression was greater (P &amp;lt; 0.01) in PRE72 heifers compared to CTRL54 and PRE54 heifers. Within treatment pairs, PR/AI were greater (P ≤0.04) when conventional semen was utilized compared to sex-sorted semen. Furthermore, PR/AI were greater (P = 0.02) in PRE72-SEX heifers than CTRL54-SEX heifers (45.8 vs. 37.5%). No difference (P = 0.20) was determined in PR/AI between CTRL54-CNV and PRE72-SEX heifers (50.5 vs. 45.8%). In conclusion, presynchronization in combination with delayed TAI increased estrus expression and PR/AI with sex-sorted semen in replacement beef heifers.

128 Pregnancy and calving rates of beef cows comparing the sex-selected semen to conventional semen using timed artificial insemination

Abstract A study was conducted over three years to determine if differences in pregnancy rates existed between the use of commercially available sex-selected (SEXED) or conventional semen (STD) coupled to fixed-time artificial insemination (TAI). A total of 240 (2016: n = 80; 2017: n = 95; 2018: n = 65) primi- or multiparous Angus or Angus-cross cows being at 45 days post-partum or greater were blocked by weight and BCS and assigned to be inseminated using SEXED semen or STD semen. Artificial insemination was performed by the same AI technicians (n = 3) across all years. All cows were subjected to estrous synchronization and insemination using the SEXED semen or STD semen with TAI between 63 and 66 h post-CIDR removal. Fourteen days post-TAI all cows were exposed to bulls for natural service. Cows were subjected to transrectal ultrasonography at day 30 and day 45 post-TAI to determine pregnancy rates and calving dates in the subsequent calving seasons were recorded to determine calving rates to TAI. Pregnancy rates were compared using a Chi-square test of two proportions. All statistical calculations were performed using JMP software and statistical significance was based on p-values less than 0.05. Pregnancy rates at day 30 and day 45 were 39.67% and 48.76% for SEXED and 47.90% and 54.62% for STD, respectively (P &amp;gt; 0.05). The percentage of calves born to TAI pregnancies for sex-selected semen and conventional semen were 22.31% and 40.34%, respectively (P &amp;lt; 0.05). These data indicate that the use of sex-selected semen can give similar pregnancy results to conventional semen in beef cow operations using TAI at day 30 of gestation; however, there was a reduction in the number of offspring to TAI comparing calving dates to animals pregnant at day 30.

Evaluation of later timepoints for split-time artificial insemination when using sex-sorted semen among beef heifers following the 14-d CIDR®-PG protocol

An experiment was designed to evaluate later timepoints for Split-Time AI (STAI), with the hypothesis that delaying AI may improve estrous response and pregnancy per AI when using sex-sorted semen. Timing of estrus was synchronized among 794 heifers using the 14-d CIDR®-PG protocol (1.38 g progesterone intravaginal insert from Day 0–14, followed by 25 mg dinoprost tromethamine on Day 30) with STAI performed based on estrous status. Heifers were blocked based on breed, source, sire, reproductive tract score (RTS), and BW and assigned within block to one of two approaches. In Approach 66, heifers that were estrual by 66 h after PG administration were inseminated at 66 h, and remaining heifers were inseminated 24 h later (90 h). In Approach 72, heifers that were estrual by 72 h were inseminated at 72 h, and remaining heifers were inseminated 24 h later (96 h). With both approaches, heifers that were non-estrual by the final timepoint were administered 100 μg gonadorelin acetate (GnRH). Within approach, heifers were pre-assigned to receive SexedULTRA 4M™ sex-sorted or conventional semen. The proportion of heifers estrual by the first timepoint was greater (P < 0.0001) with Approach 72 (76 %; 302/395) compared to Approach 66 (61 %; 242/399). The proportion of heifers pregnant as a result of AI differed (P = 0.0005) by semen type (59 % [240/404] for conventional compared with 48 % [187/390] for sex-sorted) but was not affected by approach or approach × semen type. In summary, pregnancy per AI of heifers receiving sex-sorted or conventional semen following the 14-d CIDR®-PG protocol did not differ when STAI was delayed 6 h. The proportion of estrual heifers prior to the first timepoint, however, was greater with later STAI.

Effect of reproductive management programs for first service on replacement dairy heifer economics

Our objective was to evaluate cash flow for dairy heifers managed for first service with programs that relied primarily on insemination at detected estrus (AIE), timed AI (TAI), or a combination of both. Holstein heifers from 2 commercial farms were randomized to receive first service with sexed semen after the beginning of the AI period (AIP) at 12 mo of age with 1 of 3 treatments: (1) PGF+AIE (n = 317): AIE after PGF2α injections every 14 d (up to 3) starting at the beginning of the AIP; heifers not AIE 9 d after the third PGF2α were enrolled in the 5d-Cosynch (5dCP) protocol; (2) ALL-TAI (n = 315): TAI after ovulation synchronization with the 5dCP protocol; and (3) PGF+TAI (n = 334): AIE after 2 PGF2α injections 14 d apart (second PGF2α at beginning of AIP). If not AIE 9 d after the second PGF2α, the 5dCP protocol was used for TAI. After first service heifers were AIE or received TAI after the 5dCP with conventional semen. Individual heifer cash flow (CF) for up to a 15-mo period (d 0 = beginning of AIP) was calculated using reproductive cost (rearing only), feed cost (rearing only), income over feed cost (lactation only), calf value, operating cost, and with or without replacement cost. A stochastic analysis with Monte Carlo simulation was used to estimate differences in CF for a range of market values for inputs and outputs. Time to pregnancy for up to 100 d after the beginning of the AIP was analyzed by Cox's proportional regression, binary data with logistic regression, and continuous outcomes by ANOVA. Time to pregnancy (hazard ratio and 95% CI) was reduced for the ALL-TAI versus the PGF+AIE treatment (1.20; 1.02-1.42), but it was similar for ALL-TAI and PGF+TAI (1.13; 0.95-1.33) and the PGF+AIE and PGF+TAI treatments (1.07; 0.91-1.25). The proportion of heifers not pregnant by 100 d did not differ (PGF+AIE = 7.0%; PGF+TAI = 6.5%; ALL-TAI = 6.8%). When including replacement cost, CF ($/slot per 15 mo) differences were $51 and $42 in favor of the PGF+TAI and ALL-TAI compared with the PGF+AIE treatment, and $9 in favor of the PGF+TAI compared with the ALL-TAI treatment but did not differ statistically. Excluding heifers that were replaced to evaluate the effect of timing of pregnancy differences only, the difference in CF between the PGF+AIE with the PGF+TAI and ALL-TAI treatment was the same (i.e., $15) and favored the programs that used more TAI, but also did not differ statistically. Stochastic simulation results were in line with those of the deterministic analysis confirming the benefit of the programs that used more TAI. We concluded that submission of heifers for first service with TAI only or TAI in combination with AIE generated numerical differences in CF of potential value to commercial dairy farms. Reduced rearing cost and increased revenue during lactation increased CF under fixed (not statistically significant) or simulated variable market conditions.

Semiquantitative promoter methylation of MLH1 and MSH2 genes and their impact on sperm DNA fragmentation and chromatin condensation in infertile men.

To investigate the semiquantitative methylation alterations of MLH1 and MSH2 and the possible association among methylation of MLH1 and MSH2, sperm DNA fragmentation and sperm chromatin condensation in idiopathic oligoasthenoteratozoospermic men. Seventy-five idiopathic infertile men and 52 fertile and/or normozoospermic men were included in the study. SDF was analysed using the TUNEL assay in semen samples of 100 men. Promoter methylation of MLH1 and MSH2 genes was assessed by semiquantitative methylight analysis in semen samples of 39 and 40 men respectively. Sperm chromatin condensation was evaluated using aniline blue staining in 114 men. MLH1 promoter methylation was positively correlated with the percentage of aniline blue positive spermatozoa (r=0.401, p=0.0188). On the other hand, MSH2 promoter methylation was negatively correlated with sperm concentration and total sperm count (r=-0.421, p=0.0068 and r=0.4408, p=0.009 respectively). The percentage of aniline blue positive spermatozoa in the control group was significantly lower than in the OAT group (p<0.0001) and negatively correlated with total sperm count (r=-0.683, p<0.0001), progressive sperm motility (r=-0.628, p<0.0001), total motility (r=-0.639, p<0.0001) and normal morphology (r=-0.668, p<0.0001). Promoter methylation profile of MLH1 and MSH2 genes may play role on sperm DNA packaging and conventional semen parameters respectively.

Sperm mtDNA copy number, telomere length, and seminal spermatogenic cells in relation to ambient air pollution: Results of a cross-sectional study in Jing-Jin-Ji region of China

Evidences on the association of air pollutants and semen quality were limited and mechanism-based biomarkers were sparse. We enrolled 423 men at a fertility clinic in Shijiazhuang, China to evaluate associations between air pollutants and semen quality parameters including the conventional ones, sperm mitochondrial DNA copy number (mtDNAcn), sperm telomere length (STL) and seminal spermatogenic cells. PM2.5, PM10, CO, SO2, NO2 and O3 exposure during lag0–90, lag0–9, lag10–14 and lag70–90 days were evaluated with ordinary Kringing model. The exposure-response correlations were analyzed with multiple linear regression models. CO, PM2.5 and PM10 were adversely associated with conventional semen parameters including sperm count, motility and morphology. Besides, CO was positively associated with seminal primary spermatocyte (lag70–90, 0.49; 0.14, 0.85) and mtDNAcn (lag0–90, 0.37; 0.12, 0.62, lag10–14, 0.31; 0.12, 0.49), negatively associated with STL (lag0–9, −0.30; −0.57, −0.03). PM2.5 was positively associated with mtDNAcn (0.50; 0.24, 0.75 and 0.38; 0.02, 0.75 for lag0–90 and lag70–90) while negatively associated with STL (lag70–90, −0.49; −0.96, −0.01). PM10 and NO2 were positively associated with mtDNAcn. Our findings indicate CO and PM might impair semen quality testicularly and post-testicularly while seminal spermatogenic cell, STL and mtDNAcn change indicate necessity for more attention on these mechanisms.