Gendering the beginning of life: Taiwanese gay fathers' navigation of preimplantation genetic diagnosis-assisted sex selection in transnational third-party reproduction.

Preimplantation genetic diagnosis (PGD) has been used not only to avoid genetic diseases and increase conception success rates but also to perform non-medical sex selection, particularly in the surging cross-border reproductive care (CBRC). In the context of commercialised biomedicine, assisted reproductive technologies, such as lifestyle sex selection, have been tailored to meet intended parents' preferences. However, there is a lack of analysis on how individuals' reproductive decisions on PGD-assisted sex selection were shaped within the sociocultural norms and CBRC. This article explores Taiwanese gay fathers' navigations on sex selection while seeking third-party reproduction overseas because of local legal constraints. Drawing on in-depth interviews with 53 gay fathers (to-be), I analysed how 'individual preferences' were dynamically shaped by local sociocultural norms and embedded within transnational settings of routinising PGD in chosen repro-destinations. The findings showed that gay fathers mobilised strategic discourses on non-medical sex selection from both the local and the global to negotiate their decisions in coherence with their LGBTQ+ identity and their role as sons carrying familial responsibility to procreate male heirs. This article proposed a nuanced understanding of gay fathers' reproductive practices of 'gendering the beginning of life' through PGD-assisted sex selection.

Semen sexing and its impact on fertility and genetic gain in cattle.

Semen sexing is among one of the most remarkable inventions of the past few decades in the field of reproductive biotechnology. The urge to produce offspring of a desired sex has remained since traditional times. Researchers have tried many methods for accurate semen sexing, but only the flow cytometry method has proved to be effective for commercial utilization. However, there were always concerns about the effects of sexed semen, especially on fertility and the rate of genetic gain. Some concerns were genuine because of factors such as low semen dosage in sexed semen straws and damage to sperm during the sorting process. Various researchers have conducted numerous studies to find out the effect of sexed semen on fertility and, in this article, we reflect on their findings. Initially, there were comparatively much lower conception rates (∼70% of conventional semen) but, with refinement in technology, this gap is bridging and the use of sexed semen will increase over time. Concerning genetic gain with use of sexed semen, a positive effect on rate of genetic progress with the use of sexed semen has been observed based on various simulation studies, although there has been a mild increase in inbreeding.

A balancing act: sex selection after pre-implantation genetic testing for aneuploidy for first versus second baby.

STUDY QUESTION: How often do patients undergoing frozen embryo transfer (FET) after preimplantation genetic testing for aneuploidy (PGT-A) choose to select for sex and do sex selection rates differ before and after successful delivery of a first baby? SUMMARY ANSWER: When a choice was available between male and female embryos, patients selected the sex more frequently when trying to conceive the second child (62%) as compared to the first child (32.4%) and most commonly selected for the opposite sex of the first child. WHAT IS KNOWN ALREADY: Sex selection is widely available in US fertility clinics. However, the rate of sex selection for patients undergoing FET after PGT-A is unknown. STUDY DESIGN, SIZE, DURATION: This is a retrospective cohort study of 585 patients that took place between January 2013 and February 2021. PARTICIPANTS/MATERIALS, SETTING, METHODS: The study took place at a single, urban academic fertility center in the USA. Patients were included if they had a live birth after single euploid FET and returned for at least one subsequent euploid FET. The primary outcomes were the rates of sex selection for first versus second baby. Secondary outcomes were rate of selection for same versus opposite sex as first live birth and overall rate of selection for males versus females. MAIN RESULTS AND THE ROLE OF CHANCE: Five hundred and eighty-five patients underwent a total of 1560 single euploid FETs resulting in either one or two live births. A choice between male and female euploid embryos was available for 919 FETs (first child: 67.5% (519/769) versus second child: 50.6% (400/791), P < 0.01). When a choice was available, patients selected the sex more frequently when trying to conceive the second child (first child: 32.4% (168/519) versus second child: 62.0% (248/400), P < 0.01). When sex was selected after first live birth, the opposite sex of the first child was selected 81.8% (203/248 FETs) of the time. Of transfers that involved sex selection, rates of male and female selection were similar for the first child, but selection for females was greater for the second child (first child: 51.2% (86/168) male versus 48.9% (82/168) female, second child: 41.1% (102/248) male versus 58.9% (146/248) female, P < 0.04). LIMITATIONS, REASONS FOR CAUTION: The study was performed at one urban academic medical center in the Northeastern US, which may limit generalizability to other settings where PGT-A may be performed less frequently, or sex selection may be limited or not permitted. In addition, we could not reliably account for whether patients or their partners had prior children and if so, of what sex. WIDER IMPLICATIONS OF THE FINDINGS: Patients undergoing PGT-A with both male and female euploid embryos were more likely to select for sex when attempting a second child and usually selected for the opposite sex of their first child. These findings highlight the potential for family balancing for patients who undergo PGT-A in settings where sex selection is permitted. STUDY FUNDING/COMPETING INTEREST(S): This study received no funding. The authors have no conflicts of interest to declare. TRIAL REGISTRATION NUMBER: N/A.

Biochemical Features of X or Y Chromosome-Bearing Spermatozoa for Sperm Sexing.

This review presents information on biochemical features of spermatozoa bearing X or Y chromosome, enabling production of a sperm fraction with pre-defined sex chromosome. The almost only technology currently used for such separation (called sexing) is based on the fluorescence-activated cell sorting of sperm depending on DNA content. In addition to the applied aspects, this technology made it possible to analyze properties of the isolated populations of spermatozoa bearing X or Y chromosome. In recent years, existence of the differences between these populations at the transcriptome and proteome level have been reported in a number of studies. It is noteworthy that these differences are primarily related to the energy metabolism and flagellar structural proteins. New methods of sperm enrichment with X or Y chromosome cells are based on the differences in motility between the spermatozoa with different sex chromosomes. Sperm sexing is a part of the widespread protocol of artificial insemination of cows with cryopreserved semen, it allows to increase proportion of the offspring with the required sex. In addition, advances in the separation of X and Y spermatozoa may allow this approach to be applied in clinical practice to avoid sex-linked diseases.

A fly model establishes distinct mechanisms for synthetic CRISPR/Cas9 sex distorters.

Synthetic sex distorters have recently been developed in the malaria mosquito, relying on endonucleases that target the X-chromosome during spermatogenesis. Although inspired by naturally-occurring traits, it has remained unclear how they function and, given their potential for genetic control, how portable this strategy is across species. We established Drosophila models for two distinct mechanisms for CRISPR/Cas9 sex-ratio distortion-"X-shredding" and "X-poisoning"-and dissected their target-site requirements and repair dynamics. X-shredding resulted in sex distortion when Cas9 endonuclease activity occurred during the meiotic stages of spermatogenesis but not when Cas9 was expressed from the stem cell stages onwards. Our results suggest that X-shredding is counteracted by the NHEJ DNA repair pathway and can operate on a single repeat cluster of non-essential sequences, although the targeting of a number of such repeats had no effect on the sex ratio. X-poisoning by contrast, i.e. targeting putative haplolethal genes on the X chromosome, induced a high bias towards males (>92%) when we directed Cas9 cleavage to the X-linked ribosomal target gene RpS6. In the case of X-poisoning sex distortion was coupled to a loss in reproductive output, although a dominant-negative effect appeared to drive the mechanism of female lethality. These model systems will guide the study and the application of sex distorters to medically or agriculturally important insect target species.

Characterization of semen type prevalence and allocation in Holstein and Jersey females in the United States.

Our objective was to characterize semen type prevalence and allocation to inseminate US Holstein and Jersey females by year, parity, service number, and herd size. A secondary objective was to identify the prevalence of beef breed sires selected to create beef × Holstein and beef × Jersey crossbred calves. The final data set included 8,244,653 total inseminations of 4,880,752 Holstein females across 9,155 herds, and 435,267 total inseminations of 266,058 Jersey females across 2,759 herds from October 2019 to July 2021. This data set represents approximately 42 and 27% of the total dairy cows and heifers, respectively, across approximately 40% of the total licensed dairy herds in the continental United States. Holstein and Jersey females were inseminated with 1 of 4 semen types: (1) beef, (2) conventional, (3) sexed, or (4) other dairy. The top 4 beef breeds used to produce beef × Holstein and beef × Jersey crossbred calves, respectively, were Angus (55.1 and 39.1%), Limousin (13.9, and 23.5%), Simmental (11.7 and 20.5%), and Crossbreed Beef (11.3 and 4.8%). From 2019 to 2021, the use of sexed semen to inseminate Holstein and Jersey females increased from 11.0 and 24.5% to 17.7 and 32.1%, respectively, and the use of beef semen to inseminate Holstein and Jersey females increased from 18.2 and 11.4% to 26.1 and 21.2%, respectively. The use of beef semen to inseminate Holstein and Jersey females increased with increasing parity and service number, whereas the use of sexed semen decreased with increasing parity and service number supporting that farmers used sexed semen more aggressively in higher fertility and younger females with greater genetic merit. Overall, the increase in sexed and beef semen inseminations was driven primarily by larger herds. In conclusion, sexed and beef semen inseminations in US Holstein and Jersey females increased from 2019 to 2021 and was allocated differentially based on parity and service number. This increase was driven primarily by larger dairy herds possibly due to differences in reproductive performance and economies of scale.

Sex ratio of offspring is not statistically altered following pre-implantation genetic testing under a specific sex selection policy.

PURPOSE: To determine whether the use of pre-implantation genetic testing (PGT) under a specific sex selection policy is associated with alterations in offspring sex ratio. METHODS: This was a single-center retrospective cohort study of singleton live births from January 2018-December 2020 achieved via single blastocyst non-PGT or PGT frozen embryo transfer (FET). Per institutional policy, sex may be disclosed following PGT. If both sexes are available and morphologic grade is similar, patients may select the sex of the embryo to be transferred. Demographics and cycle characteristics were compared between non-PGT vs. PGT cycles with Mann-Whitney U or χ2. Poisson regression with robust variance estimates was used to model the probability of female vs. male offspring among non-PGT vs. PGT cycles, reported as risk ratio (RR) and 95% confidence interval (CI). RESULTS(S): Among 541 live births, 350 (64.7%) were achieved with PGT and 191 (35.3%) without PGT. In both groups, female sex was more common, representing 59.4% of PGT-offspring and 55.0% of non-PGT offspring. After adjusting for potential confounders, the use of PGT was not significantly associated with an increased likelihood of female offspring (RR 1.04, 95% CI 0.98-1.11, p = 0.22). CONCLUSION(S): Singletons born following FET had a higher rate of female sex than male. Allowing sex selection per institutional policy did not increase this ratio. These results contrast with those of prior publications and should motivate individual centers to monitor their own sex ratios. As utilization of PGT increases, local, regional, and national monitoring will become increasingly important.

Evaluation of sexed semen-based artificial insemination in Tharparkar cattle under organized farm condition.

Sexed semen facilitates additional female calf production for the expansion of a herd at a faster rate and also curtails the surplus production of unwanted male calves. A study was conducted to evaluate the performance of sexed semen in indigenous Tharparkar cows based on 114 artificial inseminations (AI) performed at natural oestrus using two protocols i.e., single AI (n = 48) and double AI (n = 66). Overall, the first service conception rate (CR) was significantly higher in double (53.0%) than single (33.3%) AI protocol. The odds ratio of conception rate in double AI was 2.26 (χ2 = 4.4, df = 1, p = .04) with respect to single AI. The time that elapsed since the detection of oestrus to insemination was also analysed. In a single AI protocol, the CR was higher (p < .05) at 16 h (54.6%) than insemination at 8 h (27.0%) following the onset of oestrus. Yet, the CR using double AI protocol did not differ (p = .73) significantly when AIs were performed either at 8 h and 24 h (51.9%) or 16 h and 24 h (57.1%) post onset of oestrus. Besides, like the single AI protocol, the parity of the animals also influenced the CR, being higher in heifers (n = 22) than those of parous (n = 92) cows (72.73 vs. 40.43%, χ2 = 7.48, df = 1, p = .006) in the present study. The odds ratio of conception in heifers was 3.93 with respect to parous cows. Overall, the birth of female calf was 91.7%. In conclusion, the present study indicates a future promise of the sexed semen for the production of more female offspring from Tharparkar cattle.

A decade of molecular preimplantation genetic diagnosis of 350 blastomeres for beta-thalassemia combined with HLA typing, aneuploidy screening and sex selection in Iran.

BACKGROUND: Preimplantation genetic diagnosis (PGD) has been developed to detect genetic disorders before pregnancy which is usually done on blastomeres biopsied from 8-cell stage embryos obtained from in vitro fertilization method (IVF). Here we report molecular PGD results for diagnosing of beta thalassemia (beta-thal) which are usually accompanied with evaluating chromosomal aneuploidies, HLA typing and sex selection. METHODS: In this study, haplotype analysis was performed using short tandem repeats (STRs) in a multiplex nested PCR and the causative mutation was detected by Sanger sequencing. RESULTS: We have performed PGDs on 350 blastomeres from 55 carrier couples; 142 blastomeres for beta-thal only, 75 for beta-thal and HLA typing, 76 for beta-thal in combination with sex selection, and 57 for beta-thal and aneuploidy screening. 150 blastomeres were transferable, 15 pregnancies were happened, and 11 babies born. We used 6 markers for beta-thal, 36 for aneuploidy screening, 32 for sex selection, and 35 for HLA typing. To our knowledge combining all these markers together and the number of STR markers are much more than any other studies which have ever done. CONCLUSIONS: PGD is a powerful diagnostic tool for carrier couples who desire to have a healthy child and wish to avoid medical abortion.

Learning to Value Girls: Balanced Infant Sex Ratios at Higher Parental Education in the United States, 1969-2018.

Infant sex ratios that differ from the biological norm provide a measure of gender status inequality that is not susceptible to social desirability bias. Ratios may become less biased with educational expansion through reduced preference for male children. Alternatively, bias could increase with education through more access to sex-selective medical technologies. Using National Vital Statistics data on the population of live births in the United States for 1969-2018, we examine trends in infant sex ratios by parental race/ethnicity, education, and birth parity over five decades. We find son-biased infant sex ratios among Chinese and Asian Indian births that have persisted in recent years, and regressions suggest son-biased ratios among births to Filipino and Japanese mothers with less than a high school education. Infant sex ratios are more balanced at higher levels of maternal education, particularly when both parents are college educated. Results suggest greater equality of gender status with higher education in the United States.

Relationship between the timing of insemination based on estrus detected by the automatic activity monitoring system and conception rates using sex-sorted semen in Holstein dairy cattle.

We investigated the optimal timing of artificial insemination (AI) for achieving pregnancy according to the onset/end of estrus detected by an accelerometer system in Holstein cattle. The conception rates of conventional semen were used as a reference. The conception rate from AI of sex-sorted semen was higher at -4 to 4 h (57.1%) from the end of estrus than those at -12 to -4 h (37.7%) and 12-20 h (30.3%), whereas AI at 4-12 h showed an intermediate conception rate (47.4%). Conversely, conception rates were similar in AI performed between 0 and 32 h from the onset of estrus. Regarding conventional semen, the interval from the onset and end of estrus did not affect conception rates. The present results suggest that the time of the end of estrus is the better indicator of optimal AI timing for sex-sorted semen than the onset of estrus.

Economics of timed artificial insemination with unsorted or 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 timed artificial insemination (TAI) in combination with conventional unsorted (TCONV) and sexed (TSEX) semen in heifers only (TCONV-H, TSEX-H) and in both heifers and lactating cows (TCONV-HC, TSEX-HC) in a high-producing, pasture-based production system. The scenarios were compared with a conventional reproductive policy (CONV) in which heifers and cows were inseminated with conventional unsorted semen after estrus detection. Sensitivity analysis was also used to estimate the effect of hormone costs from TAI use on the profitability of each program relative to CONV. The mean annual (± standard deviation) profit advantage (ΔPROF) over CONV for TCONV-H, TCONV-HC, TSEX-H, and TSEX-HC scenarios were €3.90/cow ± 4.65, €34.11/cow ± 25.69, €13.96/cow ± 6.83, and €41.52/cow ± 42.86, respectively. Combined application of both technologies was shown to return a greater annual ΔPROF on average compared with that achievable from TAI alone. However, the risk of not returning a positive annual ΔPROF varied across the scenarios with higher risk in TCONV-H and TSEX-HC. Specifically, TCONV-H and TSEX-HC had a 24 and 18% chance, respectively, of not returning a positive annual ΔPROF. Sensitivity analysis showed that when hormone costs increased by €10/cow TCONV-H and TSEX-HC had a 38 and 23% chance, respectively, of not returning a positive annual ΔPROF. The range in ΔPROF for TCONV policies was most sensitive to the TAI pregnancy rate and TSEX policies were most sensitive to the relative fertility achieved with sexed compared with unsorted semen. This study has shown TAI and sexed semen are complementary technologies that can increase genetic gain and profitability in a pasture-based, dairy production system.

Perceptions towards sex selection among Jordanian population: A survey study.

Sex selection is becoming a more common practice in the society and worldwide. The current study aimed to examine the perceptions about sex selection options and possible association with sociodemographic factors and relevant characteristics. The study was a cross-sectional survey of adults in Jordan in January and February 2020 using a self-administered questionnaire. Results showed that 40.1% of respondents preferred male gender when having a child, 22.4% of respondents preferred the male gender when having a child, even if they have had children of both genders, and 71.3% preferred having children from both genders. On the other hand, 58.8% of participants preferred a male gender when there is one chance to conceive via assisted reproduction technologies. Also, among participants, 66% thought that sex selection is religiously acceptable, yet 78.0% did not support of the sex selection idea. The above factors were significantly associated with several sociodemographic variables such as gender, marital status, education, career, and place of residence, but not income. In conclusion, the current study shed a light on preferences towards sex selection in a large cohort to better understand the perception and attitude of the population towards this practice.

Differential Membrane Protein Profile in Bovine X- and Y-Sperm.

The aim of this study was to understand the molecular mechanisms behind the biological differences of X- and Y-sperm and to screen the sex-specific candidate antigen proteins for sexed semen production. To this end, we investigated differential expression of total membrane proteins of the two sperm types by using high-purity X- and Y-sperm from 20 Holstein bulls and applying the label-free proteomic technique; 1521 proteins were identified. In the X-sperm group, 8 and 23 proteins were significantly up- and down-regulated, respectively. In the X- and the Y-sperm group, 151 and 88 proteins were specifically expressed, respectively. These were overexpressed in the dynamic changes of the actin cytoskeleton, and cell senescence/apoptosis induced by the immune response, and could result in differences in the state, size, and immune sensitivity of the X-/Y-sperm membranes. The prediction of transmembrane structure, subcellular localization, and Western blotting validation results showed that the CLRN3 and SCAMP1 proteins were cell surface specific antigens of X- and Y-sperm, respectively. Our findings help explain the molecular mechanism behind the biological differences of X-/Y-sperm and lay the foundation for application of immunological methods to produce sex-sorted semen and control livestock sex. Data are available via ProteomeXchange with identifier PXD019435.

Short-term storage of semen samples in acidic extender increases the proportion of females in pigs.

BACKGROUND: Sex preselection is a desired goal of the animal industry to improve production efficiency, depending on industry demand. In the porcine industry, there is a general preference for pork from female and surgically castrated male pigs. Therefore, the birth of more females than males in a litter leads to economic benefits and improved animal welfare in the pig production industry. Our previous study suggested that the porcine semen extender (BTS) adjusted to pH 6.2 maximises the differences in viability between X-chromosome-bearing (X) spermatozoa and Y-chromosome-bearing (Y) spermatozoa without affecting sperm's functional parameters. In this study we aimed to evaluate whether the pH 6.2 extender is applicable at the farm level for increasing the number of female piglets without a decline in spermatozoa fertility. Artificial insemination (AI) was carried out with spermatozoa stored at pH 6.2 and pH 7.2 (original BTS) at day 1 and day 2 of storage. Next, the functional parameters of the spermatozoa, litter size, farrowing rate, and female-to-male ratio of offspring were determined. RESULTS: Although sperm motility decreased significantly after 2 d of storage, the viability of spermatozoa was preserved at pH 6.2 for 3 d. There was no significant difference in the farrowing rate and average litter size between the group inseminated with the spermatozoa stored in (pH 7.2) and that inseminated with spermatozoa stored in acidic BTS. The percentage of female piglets was approximately 1.5-fold higher in sows inseminated on day 1 in the pH 6.2 than in the pH 7.2 group. Furthermore, although there was no significant difference in the female-to-male ratio, the percentage of female piglets born was slightly higher in the pH 6.2 group than in the pH 7.2 group on day 2. CONCLUSIONS: The method optimised in our study is simple, economical, and may enhance the number of female births without any decline in spermatozoa fertility.

A systematic review exploring the patient decision-making factors and attitudes towards pre-implantation genetic testing for aneuploidy and gender selection.

INTRODUCTION: Pre-implantation genetic testing for aneuploidy (PGT-A) is in high demand worldwide, with ongoing debate among medical societies as to which patient groups it should be offered. The psychological aspects for patients regarding its use, lag behind the genomic technological advances, leaving couples with limited decision-making support. The development of this technology also leads to the possibility for its utilization in gender selection. Despite the controversy surrounding these issues, very few studies have investigated the psychological aspects of patients using PGT-A. MATERIAL AND METHODS: This systematic review provides an up-to-date analysis of the psychosocial aspects surrounding PGT for aneuploidy and sex selection, as well as decision-making factors. A systematic search of English peer-reviewed journals of three computerized databases were undertaken following PRISMA guidelines. The qualitative data were extracted using thematic analysis. PROSPERO Registration number: CRD42019126439. RESULTS: The main outcome measures were patients' motivations, decision-making factors, attitudes and experiences surrounding the use of PGT for aneuploidy and sex selection. Ten studies were included, four for PGT-A and six for sex selection. Attitudes towards PGT-A were positive, with the main motivating factors being decreasing miscarriage rate, reducing the risk of termination of pregnancy and reducing the time to pregnancy. Consistently raised concerns regarding PGT-A were the financial burden and moral beliefs. The vast majority of patients felt sufficiently knowledgeable to make the decision; however, studies did reveal that a minority mis-interpreted certain potential benefits of PGT-A. Studies investigating PGT for sex selection predominantly reported the main motivation was to achieve gender balance within the family dynamic, with most studies finding no difference between couples using PGT for gender selection to have male or female offspring. CONCLUSIONS: Although this systematic review was limited by the small number of studies investigating this topic, a significant minority of patients appeared to misunderstand certain benefits and limitations of PGT-A. Fertility clinics must ensure they provide adequate counseling to all patients using PGT-A. With the use of PGT-A on the rise globally, there is a need to develop decision support tools for couples who have an increasing number of genetic testing options becoming available to them.

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.

Economic impact of different strategies to use sex-sorted sperm for reproductive management in seasonal-calving, pasture-based dairy herds.

To maximize efficiency, profitability, and societal acceptance of modern dairy production, it is important to minimize the production of male dairy calves with poor beef merit. One solution involves using sex-sorted sperm (SS) to generate dairy replacements and breeding all other cows to an easy-calving, short-gestation bull with good beef merit. We used the Pasture Based Herd Dynamic Milk Model to investigate the effect of herd fertility and use of SS on farm net profit in a herd of 100 cows. This was completed by simulating herds with differing fertility performance (good, average, poor), and differing farm reproductive management [conventional semen (CONV) or SS with varying pregnancy per artificial insemination (P/AI) relative to CONV (i.e., relative P/AI 100%, 85%, and 70%)]. As an additional consideration, the method of allocating SS to cows was also examined. The first option used SS on random heifers and cows (S). The second option used SS on heifers and targeted high-fertility cows (SSel). The final option was similar to SSel, but used a fixed-time artificial insemination (AI) protocol to facilitate AI on the farm mating start date (SSync). For CONV, dairy breed semen was used for AI until 50 animals were pregnant (50% chance of a female calf), whereas for S, SSel, or SSync the target number of animals successfully conceiving with SS was set at 28 (based on assumed 90% chance of a female calf from pregnancies derived from SS). Beef breed semen was used on all other dams. The results indicated that the biggest effect on farm net profit was not based on whether or not SS was used, but instead was most affected by the overall fertility performance of the herd. Total farm profit decreased by 10% between the good and average fertility herds, and decreased by a further 12% between the average and poor fertility herds. In almost all situations, when the relative P/AI with SS was ≥85%, use of SS led to an overall increase of the farm net profit. There was an economic benefit of using either SSel or SSync compared with S for the average and poor fertility herds but not for the good fertility herd, highlighting an interaction between SS P/AI and overall herd fertility as well as management practices. If the relative P/AI with SS was <70%, the use of SS led to a decrease in profitability in all simulations except for SSync, highlighting the importance of a good management strategy for use of SS. The findings in this study indicated that SS has significant potential to help facilitate greater integration between the dairy and beef production sectors, as well as increase farm profitability when used appropriately.

Genetic consequences of terminal crossbreeding, genomic test, sexed semen, and beef semen in dairy herds.

The development of breeding tools, such as genomic selection and sexed semen, has progressed rapidly in dairy cattle breeding during the past decades. In combination with beef semen, these tools are adopted increasingly at herd level. Dairy crossbreeding is emerging, but the economic and genetic consequences of combining it with the other breeding tools are relatively unknown. We investigated 5 different sexed semen schemes where 0, 50, and 90% of the heifers; 50% of the heifers + 25% of the first-parity cows; and 90% of the heifers + 45% of the first-parity cows were bred to sexed semen. The 5 schemes were combined in scenarios managing pure-breeding or terminal crossbreeding, including genomic testing of all newborn heifers or no testing, and keeping Swedish Red or Swedish Holstein as an initial breed. Thus, 40 scenarios were simulated, combining 2 stochastic simulation models: SimHerd Crossbred (operational returns) and ADAM (genetic returns). The sum of operational and genetic returns equaled the total economic return. Beef semen was used in all scenarios to limit the surplus of replacement heifers. Terminal crossbreeding implied having a nucleus of purebred females, where some were inseminated with semen of the opposite breed. The F1 crossbred females were inseminated with beef semen. The reproductive performance played a role in improving the benefit of any of the tools. The most considerable total economic returns were achieved when all 4 breeding tools were combined. For Swedish Holstein, the highest total economic return compared with a pure-breeding scenario, without sexed semen and genomic test, was achieved when 90% sexed semen was used in heifers and 45% sexed semen was used for first-parity cows combined with genomic test and crossbreeding (+€58, 33% crossbreds in the herd). The highest total economic return for Swedish Red compared with a pure-breeding scenario, without sexed semen and genomic test, was achieved when 90% sexed semen was used in heifers combined with genomic test and crossbreeding (+€94, 46% crossbreds in the herd). Terminal crossbreeding resulted in lower genetic returns across the herd compared with the corresponding pure-breeding scenarios but was compensated by a higher operational return.

Sperm chromatin protamination influences embryo development in unsexed and sexed bull semen.

Sex selection through sperm sorting offers advantages in regards selection pressure in high-producing livestock. However, the sex-sorting process results in sperm membrane and DNA damage that ultimately decrease fertility. We hypothesized that given the role of protamines in DNA packaging, protamine deficiency could account, at least partially, for the DNA damage observed following sperm sex sorting. To test this, we compared protamine status between unsexed and sexed spermatozoa from two bulls using the fluorochrome chromomycin A3 (CMA3) and flow cytometry. Then, we assessed embryo development following in vitro fertilization (IVF) using the same sperm treatments. Overall, sperm protamination was not different between sexed and unsexed semen. However, one of the two bulls displayed higher rates of protamine deficiency for both unsexed and sexed semen (P < 0.05). Moreover, unsexed semen from this bull yielded lower blastocyst (P < 0.05) and blastocyst hatching rates than unsexed sperm from the other bull. CMA3-positive staining was negatively correlated with cleavage (R2 85.1, P = 0.003) and blastocyst hatching (R2 87.6, P = 0.006) rates in unsexed semen. In conclusion, while the sex-sorting process had no effect on sperm protamine content, we observed a bull effect for sperm protamination, which correlated to embryo development rates following IVF.