Duration: 10/01/2027 to 09/30/2032

Administrative Advisor(s):

NIFA Reps:

Non-Technical Summary

Beef and milk production depend on females conceiving on schedule, delivering a healthy calf, and successfully rebreeding. Fertilization succeeds in roughly 90% of inseminations, yet only about half produce a calf. Most of that loss occurs in the first weeks of pregnancy, and each failure costs feed, labor, and time, delays or eliminates a calf, and results in otherwise productive animals being culled. With the U.S. beef cow herd at its smallest population since 1961 and calf values at record highsthe cost of infertility has never been so great.

For more than 40 years this group has collectively worked to tackle this issue, resulting on the development of estrous synchronization protocols widely adopted nationwide, including OvSynch in dairy cattle and the CO-Synch protocols in beef. Our goal is to further improve reproductive efficiency in both sectors. Our objectives are: (1) develop and refine breeding management systems and technologies, including tools that predict fertility before breeding decisions are made; (2) determine how biology, nutrition, environment, health, and management — in both females and males — govern whether pregnancy is established and maintained; and (3) deliver science-based recommendations to stakeholders through extension, industry meetings, and publications.

Pregnancy outcomes require thousands of animals across many climates, breeds, and systems before recommendations can be trusted, and no single station can generate such evidence. Beneficiaries include beef and dairy producers, veterinarians, breeding companies, extension educators, and students. This work advances USDA science priorities for agricultural production and farm profitability.

Statement of Issues and Justification

Need as Indicated by Stakeholders

Reproductive performance is the single largest determinant of profitability in cow-calf production and a primary driver of profitability in dairy production (Trenkle and Willham, 1977; Diskin and Kenny, 2016; Lamb et al., 2016). A female that fails to conceive during the breeding season consumes feed, labor, and facility resources for a full year without generating a calf, and is typically culled. Stakeholders in both industries consistently identify reproductive failure among their most costly and least controllable production issues.

The biology underlying this problem is well characterized and remains unsolved. Fertilization succeeds in approximately 90% of inseminations in heifers, beef cows, and moderate-yielding dairy cows, yet only 40 to 50% of single inseminations result in a calf (Diskin and Morris, 2008; Diskin et al., 2012). The majority of this loss occurs before day 16 of gestation, during maternal recognition of pregnancy and conceptus elongation, and is therefore invisible to the producer until a pregnancy diagnosis weeks later (Diskin et al., 2012; Wiltbank et al., 2016; Reese et al., 2020). This gap between fertilization and calving represents the largest single opportunity to improve productivity in the U.S. cattle industries.

The economic stakes have risen substantially since this project was last renewed. As of January 1, 2026, total U.S. cattle inventory stood at 86.2 million head and the beef cow herd at 27.6 million head (USDA-NASS, 2026a), the smallest national herd in 75 years and the smallest beef cow herd since 1961 (Burdine, 2026). Calf values have set records repeatedly over the same period, averaging $524 per hundredweight in February 2026 against $378 a year earlier (USDA-NASS, 2026b). Each pregnancy generated is therefore worth more today than at any point in the history of this project, and each open female represents a proportionally larger loss. In the dairy sector, widespread use of sexed and beef semen has contracted the replacement heifer pipeline: milk cow replacement heifers stood at 3.90 million head on January 1, 2026, a multi-decade low, even as milk cow numbers rose 2% (USDA-NASS, 2026a), and replacement values have reached record levels, with milk cows averaging $3,130 per head in April 2026 (USDA-NASS, 2026b). In both industries, producers now have strong economic incentive to extract the maximum number of pregnancies from every breeding opportunity.

Global demand continues to reinforce this need. World population growth and rising per capita incomes in developing economies continue to increase demand for animal-source protein (Mensbrugghe et al., 2009; Sans and Combris, 2015), while agricultural land available to meet that demand remains essentially fixed (FAO, 2009). Increasing the reproductive efficiency of U.S. beef and dairy cattle allows greater output from a smaller national herd and is a direct route to meeting demand without additional land, feed, or water.

Originating more than 40 years ago, this project develops solutions to reproductive inefficiency in dairy and beef cattle by increasing the efficiency and predictability of reproductive programs. This is accomplished by evaluating the mechanisms that regulate reproductive processes affecting production efficiency and by disseminating reproductive management information to stakeholders in both industries.

Alignment with USDA Research and Development Priorities

This project directly advances the Secretary’s December 2025 priority of Increasing Profitability of Farmers and Ranchers by developing reproductive management systems and predictive tools that generate more calves and more marketable product per female exposed, reducing feed, labor, and replacement costs per unit of output (USDA, 2025). By accelerating the dissemination of superior genetics through artificial insemination and embryo transfer, the project also supports the priority of Expanding Markets and Creating New Uses of U.S. Agricultural Products, strengthening the competitiveness of U.S. cattle genetics in international markets.

Importance of the Multistate Effort

Beef

Advances in estrus synchronization and fixed-time artificial insemination (TAI) developed over recent decades have allowed producers to improve fertility, accelerate genetic improvement, tighten the breeding season, and shorten the calving season (Lamb et al., 2016). Despite this progress, adoption of assisted reproductive technologies (ART) in the U.S. beef industry remains low, and natural service remains the dominant breeding strategy. The most recent national survey found that only 11.6% of cow-calf operations used artificial insemination and only 7.3% used estrus synchronization, with 90.7% of beef females exposed to natural service alone (USDA, 2020). Only 37.5% of operations used any reproductive technology, and 58.7% operated without a defined breeding season (USDA, 2020). Currently recommended TAI protocols yield pregnancy rates that generally range between 40 and 60% (Lamb et al., 2016; Reese et al., 2020), so even among adopting operations, roughly half of the calf crop is not produced by AI. The rate at which superior genetics move through the commercial beef herd is correspondingly limited.

The consequences of low adoption are magnified by the current state of the national herd. With beef cow inventory at its lowest level in more than sixty years and heifer retention only beginning to increase — beef replacement heifers rose 1% to 4.71 million head on January 1, 2026, the first January increase since 2017, but retention remains below the ten-year average (USDA-NASS, 2026a; Burdine, 2026) — the reproductive performance of each retained female directly constrains the pace at which the industry can rebuild. Reproductive technologies that increase the proportion of females conceiving early in the breeding season produce older, heavier calves at weaning and more uniform calf crops, and they generate replacement heifers of known genetic merit born early in the calving season (Cushman et al., 2013).

International competitiveness is another consideration. Unless commercial beef producers implement genetic improvement through reproductive management, the U.S. risks losing its competitive position to countries such as Brazil and Argentina, both leading destinations for U.S. beef genetics and both with rapidly expanding domestic use of reproductive technologies. The proportion of Brazilian beef females bred by artificial insemination tripled between 2002 and 2019, from 5.9% to 17.8%, and a record 30.4 million semen doses entered the Brazilian market in 2025, a 15.6% single-year increase (ASBIA, 2026). Brazil has also built the most in vitro-dependent embryo industry in the world, producing 97.2% of its bovine embryos in vitro (Viana, 2025). Competitors are adopting these technologies faster than the U.S. commercial beef herd is.

Multistate research and extension efforts to maximize the use of reproductive technologies are therefore warranted and will contribute to maintaining the genetic advantage of U.S. beef herds. An important driver of ART adoption is the efficiency and predictability of these technologies. Multidisciplinary basic and applied research to maximize the efficiency and predictability of these technologies will play an important role in the future of the U.S. beef industry.

Dairy

A reproduction revolution has occurred in the U.S. dairy industry over the past three decades. Phenotypic reproductive performance in U.S. Holstein and Jersey cows, and genetic merit for daughter pregnancy rate, reversed their historical declines in the early 2000s and have improved since (Norman et al., 2009). Although genetics, nutrition, and management have all contributed, the development of fertility programs (Carvalho et al., 2018) and their adoption by dairy farmers (Caraviello et al., 2006) have driven much of this change. Fertility programs for TAI, together with strategies for pregnancy diagnosis and resynchronization of ovulation, have increased both AI service rate and pregnancies per artificial insemination (P/AI) in high-producing Holstein cows relative to AI following detected estrus (Santos et al., 2017; Barletta et al., 2017).

The economic value of this improvement is reflected on both milk production as well as through calves produced. Shortening the interval from calving to pregnancy increases the proportion of the herd in early and peak lactation at any given time, which raises herd-average milk yield per cow. Cows that establish pregnancy early also carry less excess body condition into the dry period, lose less condition after the subsequent calving, experience fewer transition-period health events, and conceive more readily at first service in the following lactation — a self-reinforcing pattern termed the high fertility cycle (Middleton et al., 2019; Fricke et al., 2023). Reproductive management is therefore a lever on milk income, herd health, and replacement supply simultaneously, and the returns to improving it compound across successive lactations rather than being realized once.

The reproductive management landscape in the dairy industry has also changed markedly since this project was last renewed. Genomic testing now allows producers to identify which females should generate replacements (Weigel et al., 2012; Lima et al., 2020), and breeding decisions have become correspondingly deliberate. Sexed semen accounted for 64% of dairy semen sold domestically in 2025, 10.6 million units, and dairy operations now purchase more than 80% of the beef semen sold domestically, 8.1 million of 9.8 million units; domestic beef semen sales have risen 36% since 2020 (NAAB, 2021, 2026). This shift reflects both the premium commanded by the crossbred calf and margin pressure from milk prices that have at times fallen below full economic cost of production — nationally in 2023, and in several major dairy states even in the profitable 2024 year (USDA-ERS, 2026) — which has given producers strong incentive to capture revenue from calf sales. The dairy herd has become a significant contributor to U.S. beef production, and reproductive management decisions made on dairy farms now influence the beef supply.

This transformation has created new reproductive management questions. Aggressive use of beef and sexed semen has contracted the replacement heifer pipeline, and producers must now balance replacement needs against crossbred calf revenue (Ettema et al., 2017; Cabrera, 2022) under conditions in which both dairy replacements and beef calves carry historically high values. Sexed semen carries a fertility deficit relative to conventional semen (Maxwell et al., 1996; DeJarnette et al., 2009), which places a premium on synchronization protocols and insemination timing optimized specifically for its use (Bombardelli et al., 2016; Hall et al., 2017; Ketchum et al., 2021). Errors in these decisions compound over the three-year interval between conception and first calving.

The economic environment for dairy producers therefore rewards precise reproductive management more than at any previous point. For U.S. dairy farms to remain competitive, strategies to optimize reproductive management technologies must be evaluated, economically modeled, and transferred to the dairy industry.

Technical Feasibility of the Research

Over more than four decades, this project has contributed substantially to the development and validation of breeding programs that optimize pregnancy rates, and has addressed the objections cattle producers commonly raise against adopting reproductive technologies. The protocols that now define reproductive management in both industries moved from single-laboratory findings to national recommendations through this committee. The OvSynch protocol was developed at the University of Wisconsin by Pursley and Wiltbank (Pursley et al., 1995) during the 1992–1997 project cycle; members at cooperating stations then conducted the field trials that established its efficacy beyond its station of origin, demonstrating that synchronized ovulation with fixed-time insemination produced pregnancy rates comparable to insemination at detected estrus across herds, regions, and management systems (Pursley et al., 1997). That paper carries six authors from five land-grant institutions — Wisconsin, Kansas State, Ohio State, Missouri, and Iowa State — and it was the multi-location evidence it reported, rather than the original single-station finding, that moved the protocol into industry practice. The same sequence — development within an individual program, validation across the committee, adoption by industry — has since been repeated for the presynchronization and fixed-time protocols now used in beef cattle. These protocols increase pregnancy rates in both beef and dairy females relative to control treatments because they induce ovulation in postpartum females that have not resumed estrous cycles by the end of the voluntary waiting period in dairy cows or by the onset of the breeding season in beef cows (Bisinotto and Santos, 2011). Protocols validated through this project are now the industry standard nationally and form the basis of the recommendations published by the Beef Reproduction Task Force and the Dairy Cattle Reproduction Council.

Work completed during the current project cycle demonstrates that this group retains the technical capacity to address the objectives proposed here. Members have established the value of presynchronization strategies for improving response to fixed-time AI protocols (Bonacker et al., 2020a, 2020b; Oosthuizen et al., 2020; Andersen et al., 2021; Mercadante et al., 2021; Ketchum et al., 2024); validated color Doppler ultrasonography for pregnancy diagnosis at day 20 of gestation, enabling substantially earlier resynchronization (Holton et al., 2022), and evaluated pregnancy-associated glycoprotein assays for on-farm determination of pregnancy status (Kline et al., 2024); characterized sire-side determinants of fertility, including nutritional and body composition effects on semen quality and paternal contributions to embryo quality (Zoca et al., 2022, 2023a, 2023b; Webb et al., 2023; Smith et al., 2025; Fontes et al., 2026); evaluated anogenital distance, reproductive tract score, and antral follicle count as pre-breeding predictors of fertility in both Bos taurus and Bos indicus-influenced females (Snider et al., 2022, 2023; Cushman et al., 2024a, 2024b; Kaps et al., 2024, 2025; Dias et al., 2025); and characterized the reproductive tract microbiome and its relationship to fertility (Webb et al., 2023; Dias, 2023; Kilama et al., 2025). Members have also examined temperament and animal handling during synchronization (Dias et al., 2022; Flax et al., 2026), immune activation and vaccination effects on ovarian and luteal function (Epperson et al., 2024), peri-insemination nutrient supply and the uterine environment (Epperson et al., 2022; Andrews et al., 2025), and one-carbon metabolism in developmental programming (Crouse et al., 2023, 2024; Hauxwell et al., 2026).

Several areas nevertheless require further investigation. The mechanisms underlying early embryonic loss remain incompletely defined, and no intervention reliably prevents it (Wiltbank et al., 2016; Reese et al., 2020). Predictive phenotypes for female fertility have been identified but not validated at the scale or across the range of environments required to support producer recommendations. Sire contributions to fertility outcomes remain underexploited relative to female-side management (Bromfield, 2014). The components of the female reproductive tract environment that determine whether spermatozoa survive transit and arrive competent at the site of fertilization are largely uncharacterized, and preliminary work from this group indicates that this environment discriminates fertility outcomes independently of the female traits currently measured (Dias, 2023). The reproductive consequences of thermal load are increasingly consequential across the southern United States and are not adequately addressed by protocols developed and validated predominantly under temperate conditions; work completed during this cycle established that shade provision and genetic selection for thermotolerance each measurably reduce thermal burden, but neither has been evaluated against fertility endpoints at the scale required for recommendations. Finally, sensor and data-driven approaches to reproductive management have advanced rapidly in the dairy sector (Valenza et al., 2012; Stevenson et al., 2014) but have not been systematically evaluated in extensive beef systems, where animal-to-handler ratios, pasture size, and infrastructure differ fundamentally from confinement dairy conditions. Each of these areas is addressed by the objectives of this proposal.

The participating stations collectively maintain the research herds, laboratory infrastructure, and technical expertise required. Members hold appointments spanning basic reproductive physiology, applied reproductive management, animal breeding and genetics, veterinary medicine, agricultural economics, and extension, and have an established record of executing coordinated protocols simultaneously across institutions.

Advantages of a Multistate Effort

A foundational goal of this group is to generate statistically valid results that are applicable and relevant to dairy and beef farms across the United States. The primary endpoint in cattle breeding trials, pregnancy, is a binomial outcome, and detecting the differences of practical significance to producers, often on the order of five to ten percentage points, requires very large sample sizes. Hundreds to thousands of females across a range of environmental conditions, from Michigan and South Dakota to Texas and Mississippi, are required before recommendations can be issued with confidence for producers operating across the varied environments of the United States. No single experiment station can generate animal numbers of this magnitude within a reasonable timeframe.

Multistate structure also captures the biological and management variation that determines whether a recommendation generalizes. Breed type, in particular the contrast between Bos taurus and Bos indicus-influenced cattle, climate, forage base, herd size, and labor availability all modify the response to reproductive interventions (Fernandes et al., 2001; Fontes et al., 2019). A protocol validated only in temperate Bos taurus herds may fail under subtropical conditions or in Bos indicus-influenced females. Testing simultaneously across stations distinguishes genuinely robust recommendations from location-specific results.

Equally important, fertility is not a single trait but a multifactorial phenotype, determined jointly by ovarian function, oocyte and embryo competence, the uterine environment, semen quality, nutrition, immune status, and the management decisions surrounding insemination. No single investigator or discipline can account for all of these determinants. The multistate structure assembles expertise in reproductive physiology, endocrinology, animal breeding and genetics, nutrition, veterinary medicine, microbiology, biostatistics, agricultural economics, and extension, allowing the same fertility outcome to be interrogated simultaneously from complementary perspectives and allowing each station to contribute the component it is best equipped to address.

The project’s own record demonstrates why this structure is necessary rather than merely convenient. A joint dairy fixed-time insemination experiment conducted under this project was replicated at seven of the nine participating experiment stations and detected a location × treatment interaction in pregnancy rates (P = 0.019) — direct evidence that protocol performance depends on where it is tested, and that validation at any single station would have produced a recommendation that failed elsewhere. Subsequent collaborative trials enrolled 2,075 replacement heifers across 12 locations in six states (Lamb et al., 2006) and 2,630 suckled beef cows across 14 locations (Larson et al., 2006), sample sizes no individual station could assemble within a project cycle. During the current cycle, members have jointly secured multiple multi-institutional competitive awards, including several USDA-NIFA AFRI grants, demonstrating that the collaborative structure attracts external investment beyond Hatch funds. Hatch support is used principally to maintain the coordinating infrastructure, standardize protocols and data collection across stations, and generate the preliminary data that make competitive proposals successful. The group also collaborates in the development of extension and outreach strategies to enhance adoption of breeding programs in both industries.

Potential Impacts from this Combined Effort

Previous work from NC1201 has already produced significant impacts in both the beef and dairy industries, and the efforts of this group have contributed directly to the current level of reproductive technology use in U.S. cattle. Protocols validated through this project are used on operations nationwide and are the basis of the recommendations published by the Beef Reproduction Task Force and the Dairy Cattle Reproduction Council.

Successful completion of the proposed work will increase the number of pregnancies established per breeding opportunity, increase the proportion of females conceiving early in the breeding season, and reduce pregnancy loss. In beef systems, shifting conception earlier increases calf age and weight at weaning and improves calf crop uniformity (Cushman et al., 2013). At current calf values, modest improvements in the distribution of conception dates translate into substantial increases in revenue per cow exposed, and extrapolated across the national cow herd represent impacts measured in hundreds of millions of dollars annually. In dairy systems, improved reproductive efficiency increases the proportion of the herd in peak lactation and therefore herd-average milk yield, reduces days open, lowers involuntary culling for reproductive failure, and allows producers to meet replacement needs while maximizing the value captured from beef-on-dairy matings (De Vries, 2006; Cabrera, 2022; Fricke et al., 2023).

Fertility is the principal driver of ART adoption, because the return on investment in these technologies rises as conception rates rise. Improvements in the efficiency and predictability of reproductive technologies are therefore expected to increase adoption itself, extending the benefit beyond operations already using these tools. Predictive tools that identify females likely to conceive before breeding decisions are made will allow producers to allocate semen, labor, and replacement resources more efficiently. Producing more calves and more milk from a smaller national herd reduces the land, feed, and water required per unit of output, ultimately improving the efficiency of beef and dairy production. The research and outreach proposed here address these issues directly, and further detail is provided in the Methods and Outreach Plan sections of this proposal.

Related, Current and Previous Work

This group has focused since its inception on developing estrus synchronization protocols that use gonadotropin-releasing hormone to control ovulation and induce a new growing cohort of follicles, a process central to all fixed-time artificial insemination (TAI) protocols in dairy and beef cattle. The committee has built on that process to develop and validate several of the TAI protocols recommended in the U.S. and throughout the world. Its defining contribution has been multi-location validation rather than invention. The OvSynch protocol, the first successful TAI protocol for dairy cattle, was developed at the University of Wisconsin by Pursley and Wiltbank (Pursley et al., 1995) during the 1992–1997 project cycle, when synchronization of ovulation was a regional project of this committee; members at cooperating stations then conducted the field trials that established its efficacy beyond its station of origin. OvSynch and its variations, including the CO-Synch protocol used in beef cattle, increase pregnancy rates by more than 20% while decreasing labor inputs.

In both dairy and beef cattle, these protocols induce ovulation followed by a normal reproductive cycle in cows during postpartum anestrus and in prepubertal heifers. This increases the opportunity for cows to become pregnant even if they have not resumed reproductive activity by the end of the voluntary waiting period in dairy herds or by the onset of the breeding season in beef herds, reducing the chances of otherwise profitable cows being culled and shortening the interval between calvings.

A signature study, “Pregnancy rates per artificial insemination for cows and heifers inseminated at a synchronized ovulation or synchronized estrus,” published in the Journal of Dairy Science by six members of this project representing five land-grant institutions — Wisconsin, Kansas State, Ohio State, Missouri, and Iowa State — has been cited more than 530 times. It led the way to understanding the impact of OvSynch on reproductive efficiency relative to insemination at detected estrus, and it helped convince the dairy industry that OvSynch could effectively manage time to first AI and reduce the number of days when cows are not in peak milk production. The impacts have changed the way dairy farmers worldwide manage reproduction, and more than 70% of dairy farms now use TAI protocols built on OvSynch.

Through joint publications, consistent with the intended outcomes of the multistate research program, this project has repeatedly demonstrated the ability to coordinate multi-location experiments in dairy and beef cattle, and its own records show why that structure is necessary. A joint dairy fixed-time insemination experiment conducted under this project was replicated at seven of the nine participating experiment stations and detected a location by treatment interaction in pregnancy rates (P = 0.019), meaning the protocol performed differently depending on where it was tested. Later collaborative trials enrolled 2,075 replacement heifers across 12 locations in six states (Lamb et al., 2006) and 2,630 suckled beef cows across 14 locations (Larson et al., 2006), animal numbers no single station assembles within a project cycle.

Over the current project cycle, efforts of NC1201 scientists have resulted in:

• 119 unique refereed journal articles, 124 including five reported as in press or accepted, and 102 peer-reviewed abstracts and conference proceedings
• $4.13 million in multi-institutional collaborative grant funding across ten named awards (federal, regional, and state), with a further $6.85 million in competitive funding named by individual stations
• 58 Extension publications and popular press articles, and 2 book chapters

Specific to this cycle, multistate efforts in beef breeding management (GA, KS, MO, MS, NM, TN, TX, VA) built on the presynchronization approaches established during the previous cycle (Oosthuizen et al., 2020; Bonacker et al., 2020a,b; Andersen et al., 2021; Mercadante et al., 2021). Two presynchronization-based fixed-time AI protocols were compared in beef cows (Ketchum et al., 2024); tandem administration of GnRH and prostaglandin F2α at days 0 and 7 was established as a convergent presynchronization method for the 7&7 Synch protocol, producing similar ovarian response among anestrous and cycling females (Palcheff et al., 2025); and the pregnancy rate improvement observed with 7&7 Synch was shown to be attributable in part to improved fertility among cows expressing estrus more than 24 hours before AI. Members are now developing an injection-only approach using human chorionic gonadotropin, having established that it induces corpus luteum formation during presynchronization without an exogenous progesterone insert, although insemination timing in the absence of the insert requires further refinement. Negative results from the same effort are equally useful to producers: a doubled GnRH dose did not improve estrus expression or pregnancy success in herds with more than 50% Bos indicus influence, while confirming the magnitude of the underlying problem, since estrus expression was 78% in Simmental against 47% in Bos indicus-influenced females.

Members also validated color Doppler ultrasonography for pregnancy diagnosis at day 20 of gestation (Holton et al., 2022) and demonstrated that deep learning algorithms interpret these examinations with performance comparable to trained human evaluators (Melo-Gonçalves et al., 2025), with early resynchronization using color Doppler raising cumulative pregnancy rates and improving calving distribution (Burato et al., 2025). A five-location trial of 920 multiparous cows established that human chorionic gonadotropin given 14 days before bull turnout did not alter the proportion bred in the first 21 days or the overall distribution of conceptions, while confirming that a corpus luteum present at the start of the breeding season predicts pregnancy.

Multistate efforts in dairy fertility programs (CA, KS, MI, NY, TX, WI) produced practical refinements to programs already in industry use. A California–Wisconsin study across four commercial dairies established that increasing gonadorelin from 100 to 200 µg at the first GnRH of breeding OvSynch raises ovulatory response from 70.8 to 83.0% and increases first-service pregnancy per AI (Lima et al., 2026). Work in Wisconsin and Kansas showed that presynchronization before a 5-day CIDR-Synch protocol raises ovulatory response in dairy heifers without raising pregnancy per AI, while the progesterone insert increases pregnancy per AI to timed AI with sex-sorted semen (Brown et al., 2026). Work in Kansas and New York established that extending proestrus in embryo transfer recipients raises estrus expression threefold and reduces pregnancy loss between the 39- and 80-day diagnoses by 44% without reducing recipient utilization, and Wisconsin produced the economic framework showing that each percentage point of 21-day pregnancy rate is worth $2 to $7 per cow annually (Lauber et al., 2026).

A sustained multistate effort to validate pre-breeding predictors of fertility (GA, KS, NC, NE, TN) reached a definitive answer. Anogenital distance was assessed in more than 2,000 commercial Bos taurus and Bos indicus-influenced females across eight locations in the United States and Brazil, detecting an association with pregnancy to TAI too small for stand-alone use (Dias et al., 2025); a subsequent evaluation of 1,262 heifers across four states found that reproductive tract score predicted pregnancy, with adjusted probability rising from 39 to 61% across the scale, whereas anogenital distance did not once body weight was accounted for. California extended the same logic to endocrine predictors in 519 lactating cows and found that anti-Müllerian hormone and inhibins associate with genomic merit and luteal phenotype but predict neither ovulation nor pregnancy. These negative findings prevent the industry from adopting measurements that do not work, and both required multistate scale to obtain.

Work on the male side of the fertility equation (GA, MI, NE, TN, TX, USDA-ARS) received comparatively little attention in earlier cycles and is now a substantial line. Members traced bull overnutrition from metabolic phenotype through semen quality to embryo development, establishing that high-gain diets produce an obese-like metabolic profile and partially decrease semen quality (Fontes et al., 2026), that backfat thickness is linearly related to failing a breeding soundness examination on sperm morphology (Smith et al., 2025), and that semen from these bulls reduces cleavage and blastocyst formation and delays developmental progression (Tariq et al., 2025). The effect appears to act on the conceptus rather than through the dam, since twelve genes were differentially expressed in day-15 conceptuses and none in the paired endometrium (Swanson et al., 2025). Michigan approached the same question through the sorting process, inseminating 884 lactating cows with conventional, X-sorted, and Y-sorted semen split from the same ejaculates, and found reduced conceptus attachment for both sorted types in multiparous cows with no difference between X and Y — evidence against chromosome content as the mechanism.

Nutritional and management efforts (GA, KS, NC, NE, TN, TX, VA) built on strategies developed in earlier cycles to maximize fertility in beef females exposed to TAI (Kruse et al., 2017; Pickett et al., 2023) and embryo transfer (Fontes et al., 2019). North Carolina showed that rumen-inert unsaturated fatty acids and rumen-protected choline alter the cotyledon transcriptome at parturition without changing gestation length or ovarian dynamics; Nebraska established that rumen-undegradable protein in late gestation nearly eliminated calving difficulty in first-calf heifers (0.3 versus 14%); and Georgia showed in 498 cows that weaning weight plateaus above a threshold cow weight while the percentage of cow body weight weaned declines steadily. Members also demonstrated that acclimating heifers to handling during the existing events of a synchronization protocol improves temperament and increases pregnancy rate to TAI at negligible cost (Dias et al., 2022; Flax et al., 2026). On the thermal side, North Carolina recorded a 0.5 to 2 °C reduction in body temperature from integrated silvopasture at equivalent temperature-humidity index, Texas showed that calves carrying the slick PRLR allele maintain lower rectal temperatures and shed hair earlier, and California published a review of strategies to sustain fertility under heat stress (Lima, 2026).

Work on the mechanisms regulating reproductive processes (KS, MI, ND, NE, TN, TX, USDA-ARS, WY) established that modified live viral vaccines containing infectious bovine rhinotracheitis antigen alter cytokine concentrations and disrupt luteal function, producing abnormal estrous cycles even in previously vaccinated animals (Epperson et al., 2024) — a finding that bears directly on the timing of herd health programs relative to breeding. Michigan reframed where the remaining gains lie by measuring where pregnancies are lost: following Double-OvSynch, 94% of inseminated cows showed gene expression consistent with an elongating conceptus at day 14, 71% achieved conceptus attachment, 58% were diagnosed pregnant at day 34, and 43% calved, with 94% of early losses attributable to embryonic mortality rather than luteolysis. Members characterized the reproductive tract microbiome and its relationship to fertility (Dias, 2023; Webb et al., 2023; Kilama et al., 2025), and Kansas and Tennessee established that vaginal fluid collected at insemination preserves sperm motility ex vivo differently depending on estrus expression and progesterone device use, giving the group a functional assay for the female tract environment.

This project has also continued to innovate in Extension and outreach. Through the Dairy Cattle Reproduction Council and the Beef Reproduction Task Force, described further in the Outreach Plan, results reach producers through artificial insemination and reproductive management schools, dairy fertility workshops, webinars, and podcasts. Since January 2025 the beefrepro.org site has recorded more than 104,400 views by 24,800 active users in 129 countries and 14,200 downloads, with more than 1,100 users of the web-based Estrus Synchronization Planner since November 2025; the Task Force YouTube channel has accumulated more than 1,700 subscribers and 59,400 views with an audience in 36 countries, and its Facebook page recorded over 146,000 content views since March 2025. The Applied Reproductive Strategies for Beef Cattle conference drew 183 participants in 2022, 198 in 2023, 205 in 2024, and 194 in 2025, with veterinary and animal science continuing education credit offered each year. In a single year members at one station delivered 27 programs to 4,787 attendees and at another 39 stakeholder presentations to roughly 3,744 participants, and Kansas Dairy Fertility Roundtables delivered jointly with Wisconsin and Texas reached stakeholders representing approximately 70% of the Kansas dairy herd.

More unusually for a research project, members have published formal evaluations of that programming. North Carolina assessed 140 participants across reproduction management and artificial insemination schools drawn from 18 counties and five universities, using retrospective pre- and post-training instruments. Knowledge gain was greatest for hands-on skills, 96.3% of participants reported being very satisfied, 61% planned to develop a reproductive management program, 52% planned to incorporate estrous synchronization and artificial insemination, and 53% anticipated an economic benefit between $1,000 and $10,000.

These accomplishments also define the boundaries of current knowledge, and six areas require further investigation. The mechanisms underlying early embryonic loss remain incompletely defined and no intervention reliably prevents it (Wiltbank et al., 2016; Reese et al., 2020), although this cycle located the losses precisely. Predictive phenotypes for female fertility have been identified but not validated across the range of environments required for producer recommendations. Sire contributions remain underexploited relative to female-side management (Bromfield, 2014), and the sexed-semen deficit has been localized to conceptus attachment without being explained. The components of the female reproductive tract environment that determine whether spermatozoa arrive competent at fertilization are largely uncharacterized. Neither thermal mitigation nor selection for thermotolerance has been tested against pregnancy outcomes at scale. Finally, sensor and data-driven approaches advanced rapidly in the dairy sector (Valenza et al., 2012; Stevenson et al., 2014) but have not been evaluated in extensive beef systems. Each is addressed by the objectives of this proposal.

Several active multistate projects address reproduction in livestock, and they are complementary rather than duplicative. NE2227 examines the cellular and molecular contributions of ovarian function, uterine receptivity, and embryo quality to pregnancy success in ruminants; its unit of analysis is the tissue or transcript, whereas NC1201 takes pregnancy itself as its endpoint and tests whether interventions change it at the scale required for recommendations. The two are sequential, and the members who participate in both provide the route for translation. W5112 covers domestic ruminants across the Western region and includes sheep and goats, a breadth of species and regional focus that distinguishes it from the cattle-specific, national scope of NC1201. W5171 focuses on germ cell and embryo development and manipulation, laboratory work directed at improving the technologies themselves rather than their application in production settings. S1093 addresses beef cattle management systems in subtropical and tropical environments with reproduction among several concerns, and coordination with its participants would extend the environmental range over which this project can validate recommendations. NCERA57 and S1081 address swine and do not overlap.

The proposed work supplements rather than repeats the previous project. Where the expiring cycle established that sire nutrition affects semen quality and embryo development, the proposed work asks whether that effect is large enough to change pregnancy outcomes under commercial conditions. Where it determined that anogenital distance does not function as a stand-alone selection tool, the proposed work asks which combinations of phenotypes reach practical thresholds within defined breed types and environments. Where it located pregnancy losses in the interval between elongation and attachment, the proposed work asks what in the female reproductive tract environment determines whether that interval is survived. In each case the transition is from demonstrating that a factor matters to determining whether managing it changes what producers can achieve.

Objectives

1. Develop and refine reproductive management systems and technologies to increase the efficiency and predictability of pregnancy establishment in beef and dairy cattle.
   
2. Determine the biological, nutritional, environmental, and management factors, in both females and males, that regulate reproductive success in beef and dairy cattle.
   
3. Deliver science-based reproductive management recommendations to cattle producers, veterinarians, and allied industry personnel to improve reproductive efficiency in beef and dairy herds.
   

Methods

Objective 1

Develop and refine reproductive management systems and technologies, including tools that predict fertility before breeding, to increase the efficiency and predictability of pregnancy establishment in beef and dairy cattle (CA, GA, KS, MI, MO, NC, NE, TN, TX, WI)

Use of presynchronization strategies to optimize fertility in fixed-time artificial insemination protocols

Increased adoption of assisted reproductive technologies in the beef industry relies upon the continued development of new protocols, or modification of existing ones, to increase conception rates to timed artificial insemination (TAI). Presynchronization with a progesterone insert in combination with an injection of prostaglandin F2α seven days before the beginning of a 7-day CO-Synch + CIDR protocol increases response to the first GnRH (Bonacker et al., 2020a; Mercadante et al., 2021), resulting in increased estrus expression and pregnancy rates to TAI (Oosthuizen et al., 2020; Andersen et al., 2021) and embryo transfer (Bonacker et al., 2020b). Work during the current cycle established that tandem administration of GnRH and prostaglandin F2α at days 0 and 7 produces a convergent ovarian response among anestrous and cycling females (Palcheff et al., 2025), and that human chorionic gonadotropin induces corpus luteum formation during presynchronization without an exogenous progesterone insert, although insemination timing in the absence of the insert requires further refinement. Collaborative multistate efforts to add presynchronization will continue, including completion of an injection-only approach and continued evaluation of presynchronization in Bos indicus-influenced females that respond poorly to the initial GnRH (Fernandes et al., 2001).

Evaluating estrus synchronization protocols specific to the use of sex-sorted and beef semen

Timing of insemination relative to ovulation affects fertilization rate and embryo quality, and when sex-sorted semen is used the optimal timing of artificial insemination is thought to be later, closer to ovulation, than when conventional semen is used. Because of the variability among females in timing of insemination relative to ovulation when TAI is performed, it remains unclear whether optimal timing differs by semen type; studies in which TAI was performed at later times suggest no difference (Hall et al., 2017; Ketchum et al., 2021). Improvements associated with later timing may be realized in a protocol-specific manner and are more likely to be observed where presynchronization alters the timing of estrus onset (Oosthuizen et al., 2020). Research efforts within our groups will continue to evaluate optimal timing of insemination with sex-sorted semen in a protocol-specific manner and in conjunction with presynchronization, will extend this work to beef semen used in dairy herds, and will continue collaborative evaluation of fresh and frozen multi-sire and single-sire semen in commercial beef heifers.

Combining color Doppler ultrasonography and machine learning with resynchronization to decrease the interval between artificial inseminations

Resynchronization programs maximize the proportion of pregnancies generated via reproductive technologies (Epperson et al., 2020), but the long interval between breeding events, approximately 30 to 40 days, limits their adoption, as producers focus on generating pregnancies early in the breeding season. The main factor increasing that interval is the period between first breeding and pregnancy diagnosis, conventionally limited to days 28 to 30 of gestation (Nation et al., 2003). Research from this group established that color Doppler examination of the corpus luteum can diagnose pregnancy on day 20 of gestation in Bos taurus beef females (Holton et al., 2022), and subsequent work demonstrated that deep learning algorithms interpret these examinations with performance comparable to trained human evaluators (Melo-Gonçalves et al., 2025). Based on these results we propose to evaluate color Doppler in combination with early resynchronization to increase the proportion of genetically superior pregnancies while minimizing the interval between the first and second insemination, with pregnancy-associated glycoprotein assays evaluated in parallel as an on-farm alternative.

Refinement of established fertility programs for timed artificial insemination in dairy herds

Fertility programs built on OvSynch are used on most U.S. dairy farms, so incremental refinements reach large numbers of cows at low cost. Work during the current cycle established that increasing gonadorelin from 100 to 200 µg at the first GnRH of breeding OvSynch increases luteinizing hormone release, ovulatory response, and first-service pregnancy per artificial insemination across commercial dairies in California and Wisconsin, with the greatest benefit in multiparous cows (Lima et al., 2026). In parallel, a simplified fertility program evaluated across Kansas, Texas, and Wisconsin produced pregnancy per artificial insemination comparable to Presynch-OvSynch but produced an unanticipated distribution of estrus-based and timed inseminations. Research will focus on evaluating gonadorelin dose and timing across additional herds, parities, and production levels, and on refining the voluntary waiting period of the simplified program before broad commercial application.

Evaluating the role of progesterone and presynchronization in synchronization of dairy heifers

In contrast to lactating cows, dairy heifers respond poorly to synchronization protocols based solely on GnRH and prostaglandin F2α (Pursley et al., 1997), owing to differences in circulating progesterone concentrations (Sartori et al., 2004) and an increased rate of follicular wave turnover (Bisinotto and Santos, 2012), both of which decrease protocol synchrony (Lima et al., 2013). Inclusion of an intravaginal progesterone insert prevents heifers from displaying estrus until insert removal and thereby increases synchrony (Rivera et al., 2005). Work during the current cycle showed that presynchronization with prostaglandin F2α two days before a 5-day CIDR-Synch protocol decreased progesterone and increased ovulatory response at initiation but did not increase pregnancy per artificial insemination, whereas inclusion of the progesterone insert decreased early expression of estrus and increased pregnancy per artificial insemination to timed AI with sex-sorted semen (Brown et al., 2026). Research will focus on determining the progesterone exposure required to achieve synchrony without suppressing fertility, and whether the interaction between progesterone and semen type extends to lactating cows.

Managing proestrus in embryo transfer recipients

Pregnancy loss between the initial and confirmatory diagnoses is a substantial and largely unmanaged source of inefficiency in embryo transfer programs. Work conducted across Kansas and New York established that delaying the final GnRH of a Double-OvSynch protocol increases estrus expression threefold and reduces pregnancy loss between the 39- and 80-day diagnoses by 44%, without reducing the proportion of cows eligible to receive an embryo, locating the benefit of a longer proestrus in pregnancy maintenance rather than in initial establishment. Research will focus on defining that mechanism through preovulatory estradiol exposure and subsequent luteal function, and on determining whether the same approach reduces pregnancy loss in beef embryo transfer recipients.

Validating pre-breeding phenotypes that predict fertility

Selection on phenotypes that can be measured before breeding would allow producers to allocate semen, labor, and development costs more efficiently. Anogenital distance was evaluated in more than 2,000 commercial Bos taurus and Bos indicus-influenced females across eight locations in the United States and Brazil, detecting an association with pregnancy to TAI too small for stand-alone use (Dias et al., 2025). A subsequent evaluation of 1,262 beef heifers across four states found that reproductive tract score predicted pregnancy to TAI, with adjusted pregnancy probability rising from 39 to 61% across the scale, whereas anogenital distance did not once body weight was accounted for. These results support reproductive tract score as a pre-breeding selection tool and constitute a clear negative finding for anogenital distance used alone, an outcome that required multistate scale to obtain. Research will focus on determining whether combinations of phenotypes, including reproductive tract score, antral follicle count, and anti-Müllerian hormone, achieve practical predictive thresholds within defined breed types and environments, so that results translate into a management decision rule rather than an association.

Objective 2

Determine the biological, nutritional, environmental, and management factors, in both females and males, that regulate reproductive success in beef and dairy cattle

Beef Cattle (GA, KS, ND, NC, NE, TN, TX, USDA-ARS, VA, WY)

Evaluating the mechanisms associated with early pregnancy establishment

Fertilization succeeds in approximately 90% of inseminations, yet only 40 to 50% of single inseminations result in a calf (Diskin and Morris, 2008; Diskin et al., 2012), with the majority of that loss occurring before day 16 of gestation. Conception early in the breeding season and maintenance of that pregnancy require many mechanisms to be in synchrony, and heifers calving in the first 21 days of the calving season have increased longevity in the cow herd (Cushman et al., 2013). Work during the current cycle demonstrated that heifers with high antral follicle counts show delayed endometrial preparation for luteolysis, suggesting a wider window for maternal recognition of pregnancy (Kaps et al., 2025), and established that cows experiencing late embryonic and early fetal mortality are less likely to conceive within the breeding season, calve later, and wean fewer pounds of calf than either cows maintaining the pregnancy or cows failing to conceive (Gonçalves et al., 2025). Research will focus on identifying the mechanisms essential to establishing a pregnancy across the interval spanning maternal recognition and conceptus elongation, including preovulatory steroid production, estrus expression, the influence of the ovarian reserve on oocyte quality and uterine function, and the consequences of early pregnancy for the subsequent productivity of the offspring.

Investigating male-related factors influencing pregnancy rates in beef herds

As the use of estrus synchronization and TAI increased, it became apparent that certain sires achieved poorer conception rates under TAI than under natural service or detected estrus. Components of the ejaculate must work in conjunction with the maternal system to create a uterine environment that supports establishment and maintenance of pregnancy, yet the role of ejaculate components as mediators of inflammation and their influence on the uterine environment remain poorly understood (Bromfield, 2014). Work during the current cycle traced bull overnutrition from metabolic phenotype through semen quality to embryo development, establishing that high-gain diets produce an obese-like metabolic profile and partially decrease semen quality (Fontes et al., 2026), that subcutaneous backfat thickness is linearly related to the probability of failing a breeding soundness examination on sperm morphology (Smith et al., 2025), and that semen from these bulls reduces cleavage and blastocyst formation and delays developmental progression (Tariq et al., 2025). Supplementation with omega-3 fatty acids during development improved sperm motility and morphology and mitigated these effects. Research will focus on understanding the male-related factors that influence sperm function, fertility, and early embryo development, and on determining whether the effects established in vitro translate into measurable differences in pregnancy outcomes under commercial breeding conditions.

Investigating the interaction between spermatozoa and the female reproductive tract environment

Spermatozoa deposited at insemination must survive transit through an environment whose composition varies with cycle stage, exogenous hormone treatment, and inflammatory status, and preliminary work from this group established that this environment discriminates fertility outcomes. Vaginal fluid collected at device removal from beef heifers on a 7-day CO-Synch + CIDR protocol and challenged ex vivo with semen from each heifer’s own sire sustained motility equally at collection but diverged by three hours, fluid from subsequently pregnant heifers preserving roughly twice the progressive and total motility of fluid from open heifers. The association with pregnancy strengthened after adjustment for sire, and sperm exposed to fluid from open heifers fell below both neat-semen and buffer controls, indicating that such fluid actively depresses sperm survival rather than merely failing to support it. Vaginal pH, device-induced vaginitis score, estrus expression, and visual appearance of the fluid did not explain the effect. Research will focus on identifying the responsible components using banked and prospectively collected fluid, applying a redox panel, untargeted metabolomics, and microbial community profiling, then testing candidate mediators in the ex vivo assay and evaluating confirmed mediators against fertility endpoints across stations.

Investigating immune determinants of luteal function

Prevailing recommendations hold that vaccination carries no reproductive consequence in previously exposed animals, and work from this group contradicts that position. Modified live viral vaccines containing infectious bovine rhinotracheitis antigen alter cytokine concentrations and leukocyte populations and disrupt luteal function, producing abnormal estrous cycles even in previously vaccinated animals, whereas bovine viral diarrhea antigen alone produced no such effect (Epperson et al., 2024). Females that subsequently cycled abnormally showed elevated interferon-gamma three days after vaccination, and eight cytokines differed between animals with normal and abnormal cycles. Research will focus on defining the immunological pathway linking vaccination to impaired luteal function and on evaluating the timing of vaccination relative to breeding across multiple locations, so that herd health and breeding programs can be scheduled without compromising either.

Determining nutritional and thermal influences on reproductive success

Nutritional strategies developed under this project have altered commercial practice, including fatty acid supplementation and mitigation of post-insemination nutrient restriction in heifers moving from feedlot to grazing settings (Kruse et al., 2017; Pickett et al., 2023), and work on one-carbon metabolism has advanced understanding of how maternal micronutrient supply programs fetal development (Crouse et al., 2024; Hauxwell et al., 2026). Thermal load imposes substantial reproductive and economic losses (St-Pierre et al., 2003) and is not adequately addressed by protocols developed and validated predominantly under temperate conditions. Work during the current cycle established two tractable routes: shade provided through integrated silvopasture lowered body temperature by 0.5 to 2 °C during the warmest hours of the day at equivalent temperature-humidity index, and calves carrying the slick PRLR allele maintained lower rectal temperatures and shed hair earlier than non-carriers. Research will focus on continued evaluation of supplementation against fertility and developmental programming endpoints, and on extending both thermal mitigation and selection for thermotolerance against fertility endpoints at southern stations to determine which route is the more tractable.

Dairy Cattle (CA, KS, MI, NY, WI)

Evaluating the impact of sex-sorted semen on conceptus development and pregnancy loss

Sex-sorted semen now accounts for roughly two-thirds of the dairy semen sold domestically, yet it carries a fertility deficit relative to conventional semen whose origin remains unresolved, attributed in part to a capacitation-like state induced by sorting (Maxwell et al., 1996; DeJarnette et al., 2009). Work during the current cycle localized that deficit rather than explaining it. Insemination of lactating cows with conventional, X-sorted, and Y-sorted semen split from the same ejaculates reduced conceptus attachment for both sorted types relative to conventional, with the effect confined to multiparous cows and no difference between X- and Y-bearing sperm, which argues against chromosome content as the mechanism. In vitro, sorting reduced cleavage and blastocyst development, and transfer of embryos derived from sorted semen underperformed timed AI while the two were equivalent for conventional semen. Research will focus on determining whether the deficit arises during sperm transport, at fertilization, or during early conceptus development, and whether it can be mitigated through insemination timing, progesterone supplementation, or selection of sires whose semen tolerates sorting.

Investigating endocrine and genomic predictors of fertility in dairy females

Identifying which females are likely to conceive before breeding decisions are made would allow more efficient allocation of sex-sorted, conventional, and beef semen. Genomic prediction of daughter pregnancy rate is positively associated with pregnancy at first service, days to first service, and time from calving to pregnancy in herds receiving timed AI (Lima et al., 2020), and with larger ovulatory follicles and greater ovulatory response (Veronese et al., 2019). Work during the current cycle evaluated circulating anti-Müllerian hormone and inhibins A and B in genomically characterized lactating cows and found each associated with parity, genomic prediction of daughter pregnancy rate, and luteal phenotype, yet neither predicted ovulation nor pregnancy per artificial insemination in multivariable or receiver operating characteristic analysis, a negative result that bounds the usefulness of single endocrine markers. Research will focus on characterizing synchronization response and hormonal profile in genotyped cows and heifers, and on determining whether combinations of genomic and endocrine measures reach practical predictive thresholds.

Evaluating the luteotropic mechanisms associated with the use of nerve growth factor-β

Circulating progesterone after insemination contributes to pregnancy maintenance, and strategies to raise it through exogenous supplementation or human chorionic gonadotropin have produced inconsistent effects on pregnancy rates (Stevenson et al., 2007; Rizos et al., 2012), in part because the timing of administration appears critical (Parr et al., 2017). Data from this group indicate that nerve growth factor-β, a protein abundant in bovine seminal plasma, administered at the time of the final GnRH of a synchronization protocol augments progesterone in a manner resembling the physiological increase reported in cattle. Work during the current cycle established that supplementation of maturation and fertilization media with nerve growth factor-β improves cleavage and embryonic development in vitro and induces transcriptional changes in follicular wall cells. Research will determine the mechanisms by which nerve growth factor-β elicits its luteotropic effects across the hypothalamic-pituitary-ovarian axis, and whether those responses can be harnessed therapeutically or used as a target for genomic selection.

Objective 3

Deliver science-based reproductive management recommendations to producers, veterinarians, and allied industry personnel to increase adoption of reproductive technologies in beef and dairy herds (per Appendix E)

A description of Objective 3 is available in the Outreach Plan section of this proposal.

 

Measurement of Progress and Results

Outputs

• All research proposed herein will be completed during the 5-year proposal period. Results of research will be published in experiment station reports, refereed publications, and in popular press articles. Research results will also be delivered to stakeholders in Extension meetings described in the outreach portion of this proposal. In addition, decision aid tools will be developed to assist cattle producers to enhance their ability to incorporate new reproductive management practices into their operations.
• Outputs will also include multi-location datasets on reproductive performance in beef and dairy cattle, updated protocol recommendations disseminated through the Beef Reproduction Task Force and the Dairy Cattle Reproduction Council, and biological samples and associated analytical data retained and shared among participating stations.

Outcomes or Projected Impacts

• The main outcome of the experiments proposed herein is to enhance animal production and animal products in the U.S. through the development and dissemination of assisted reproductive technologies (ART). Therefore, the proposed effort fits current priority areas identified by the USDA. In beef cattle, suboptimal fertility results in cows failing to become pregnant or becoming pregnant later in the breeding season. The estimated cost of pregnancy failure in beef herds is approximately 1 billion dollars annually in the U.S. In addition to the costs associated with pregnancy failure, 1.1 kg of weaning weight is lost per calf for each day in which conception is delayed. This occurs because cows that become pregnant later in the breeding season, and consequently calve later in the calving season, produce younger and lighter calves at weaning. Work from this group has shown that estrus synchronization and TAI increase the proportion of cows becoming pregnant in the beginning of the breeding season and consequently increase weaning weights by 17 kg per cow exposed to the breeding season. It is estimated that 2 to 3 million beef females are exposed to these synchronization programs today. Increasing the performance of ART and expanding their use through the research and outreach efforts of this proposal could result in more than 460 million additional kilograms of weight in calves at weaning, worth several billion dollars at current calf values, and substantially impact the profitability of cow-calf producers. Additionally, this would be accomplished while disseminating superior genetics across the industry which would indirectly improve profitability in other segments of the beef industry, such as feedlots and retailers.
• Recent studies reveal that cows are being sold or culled from herds at alarming rates due to reproductive inefficiencies, an issue costing the U.S. dairy and beef industries over $1 billion each year. Dairy farmers whose cows do not conceive before 130 days in milk annually lose about $380 per cow. Economic modeling conducted under this project has shown that incremental improvements in 21-day pregnancy rate carry substantial value per cow, which across the national dairy herd represents hundreds of millions of dollars annually. Shortening the interval from calving to pregnancy also increases the proportion of the herd in peak lactation and therefore herd-average milk yield, reduces transition-period disease, and improves fertility in the subsequent lactation. Improved reproductive efficiency further allows producers to meet replacement needs while capturing the value of beef-on-dairy matings, a decision that now influences national beef supply as well as individual farm profitability. Strategies to optimize reproductive management technologies must therefore be evaluated, economically modeled, and transferred to the dairy industry, and the research and outreach proposed herein address these challenges directly.

Milestones

(2027):Initiate the proposed experiments associated with the refinement of reproductive programs, and with the discovery of nutritional, physiological, environmental, and molecular factors that impact beef and dairy cattle fertility.

(2028):Generate preliminary reports describing the factors associated with fertility in cattle and generate multistate data for optimization of reproductive programs.

(2029):Initiate summaries of updated recommendations based on the findings obtained during the first two years.

(2030):Disseminate information to the scientific community, cattle producers, veterinarians, and industry professionals.

(2031):Publish findings in peer-reviewed scientific journals.

Projected Participation

View Participation Form/Appendix E: Participation

Outreach Plan

Beyond refereed and Extension publications, NC1201 members have led two outreach organizations that work with university Extension and research communities, the pharmaceutical and AI industries, and the veterinary community.

The Dairy Cattle Reproduction Council (dcrcouncil.org) raises awareness of issues critical to reproductive performance in dairy cattle and delivers the latest technology and resources to the industry.

The Beef Reproduction Task Force (beefrepro.org) identifies the most reliable beef cattle reproduction management strategies and develops methods for delivering them into Extension programs.

These organizations provide unique means for multistate dissemination of science-based information through annual conferences, webinars, and experiential learning programs, much of it free through YouTube and online publications; since January 2025 the Task Force website alone recorded over 104,400 views by users in 129 countries. Programming is delivered bilingually where the workforce requires it, and Extension personnel outside this group use these materials.

Impacts include:

• Increased adoption of profitable timed AI in U.S. dairy and beef herds, with estimated savings of $80 per cow per year since the initial collaborative study in 1997; these programs are now the basis for many used worldwide
• Fertility programs give dairy farmers confidence to use sex-sorted semen on top genomic-ranked cows and beef semen on the remainder, now 64% and over 80% of domestic dairy and beef semen sales
• Approximately 2 million beef cows undergo TAI annually in the U.S., a producer gain of $49 per cow after weaning
• Documented learning gains, with 96.3% of participants in recent Extension schools very satisfied and 52% planning to adopt estrous synchronization and AI

The proposed project will continue to manage these programs and use this structure to share ongoing developments, disseminating recommendations that increase productivity and profitability of beef and dairy herds.

Organization/Governance

The technical committee will consist of at least 1 officially designated representative from each participating agricultural station in the region. The technical committee will meet annually. USDA-NIFA will designate one nonvoting representative. Officers will be elected for a rotating period of 3 years, consisting of Chair, Secretary and a Member-at-Large. Officers rotate from Member-at-Large to Secretary to Chair during each subsequent year. Elections will be held at the annual meeting. Officers will compose the executive committee. The executive committee, together with the administrative advisor, is authorized to function on behalf of the technical committee in all matters pertaining to the regional project interim action.

The chair, in consultation with the administrative advisor, will arrange the time and place of the meeting, notify technical committee members of the meeting site, and prepare the agenda. The Chair is responsible for preparation of the annual report of the regional project. The Secretary will record and distribute minutes of the annual meeting. Subcommittees may be appointed by the Chair as needed for specific assignments. The executive committee will be in charge of coordinating the cooperative research trials.

For each multi-location trial, the executive committee will designate a coordinating investigator responsible for finalizing the common protocol and data dictionary before enrollment begins, receiving and merging station datasets, conducting the pooled analysis, and leading preparation of the resulting manuscript. Authorship will reflect station contribution.

Literature Cited

Attachments

Land Grant Participating States/Institutions

AR, CA, GA, KS, MI, MO, NC, ND, NE, TN, TX, UT, VA, WI, WY

Non Land Grant Participating States/Institutions