The need as indicated by stakeholders.  Reproductive performance in beef and dairy cattle is often suboptimal resulting in increased intervals to conception and/or rebreeding failures which collectively reduces farm revenue due to the effect on milk and calf production efficiencies. Causes of pregnancy failure in cows include lack of resumption of cyclicity (anovulation/ anestrus), fertilization failure, poor oocyte quality, suboptimal hormonal environment due to abnormalities in follicle or corpus luteum, abnormalities in embryonic development and uterine-conceptus interactions, and pregnancy loss. Any of these reproductive problems can lead to reproductive inefficiency, increased culling, and substantial economic losses. Reduced fertility in ruminants also affects the consumer because reduced farm efficiencies (i.e., fewer calves per year and reduced milk production efficiency) reduce product supply and/or increase cost.

Importance of work and consequences if it is not done. Improving fertility in ruminants requires fundamental knowledge about endogenous and exogenous influences on 1) follicle activation and development and oocyte growth and maturation; 2) corpus luteum development, steroidogenesis, and regression; 3) fertilization and pre-attachment embryo development; 4) conceptus-uterine-ovarian interactions; and 5) placental development and function.  Understanding ovarian, uterine, and embryo attributes is critical to identify the underlying causes of anovulation, fertilization failure, luteal insufficiency, and pregnancy loss in ruminants, each of which are the critical causes of reduced fertility. This will lead to development of novel and innovative management strategies designed to optimize fertility, and therefore, may lead to management strategies and therapeutics that improve reproductive efficiency and are economical, user and consumer friendly, while still ensuring food quality and safety.

Advantages of performing this work as a multistate effort. We are the first multi-state group established and from its initial inception (NE-1) has been one of the most productive, cohesive, diverse, and collaborative multistate research groups nationwide. Complementary expertise of the group has led to collaborative experimental efforts and incorporation of new technologies that were integrated and directed toward exponential progress of previous objectives. The group uses a variety of animal models that are best suited to address specific molecular and cellular questions associated with tissue function. Additionally, members at different stations have developed best practices for animal and cell culture protocols, conducted collaborative experiments, and exchanged samples to take advantage of unique validated procedures. The commitment of participants to the multistate project is exemplified by numerous collaborative publications, including one in which it was decided to list the project itself as the author, rather than individuals ¹. In addition to research collaborations, the group developed a multi-institution graduate course in reproductive biology. Furthermore, senior members of the group serve as mentors for junior investigators as they develop internationally recognized research programs and become leaders in the field of reproductive biology.

The technical feasibility of the work. The technical members of NE-1727 (molecular biologists, cell physiologists, reproductive physiologists, animal scientists, and veterinarians) are a diverse group of scientists with broad and complementary expertise in follicle growth, corpus luteum function, oocyte development, conceptus-uterus-ovary interactions, reproductive immunology, and reproductive management of ruminants. Recent additions of members with expertise in ovarian reserve and activation of follicle growth, follicle deviation, genomics of oocyte development and maturation, and pre-implantation embryo development will fill important gaps in knowledge to understand pregnancy loss more effectively in cattle. This shared expertise and wide array of technical capabilities has previously fostered more rigorous and impactful research. Moreover, the combination of basic biological research and innovative applied research more effectively support outreach programs and engagement, the goal of which is to improve reproductive performance in livestock more rapidly. This experimental paradigm will be continued in the newly proposed objectives.

Impacts from successfully completing the work. Specific impactful discoveries from the group include, but are not limited to:

• Roles of pro-inflammatory cytokines and environmental stressors on follicle growth, steroidogenesis, luteal regression, and conceptus-uterine-immune interactions.


• Use of trace mineral supplementation to improve oocyte quality and increase systemic progesterone concentrations.


• Impact of beef cow body condition score and weight on the metabolome of follicular fluid and serum


• Genetic determinants of ovulation and implantation rates


• Endocrine and molecular mechanisms controlling ovulation rate in cows


• Mechanisms associated with preimplantation embryo development and quality.


• Reproductive management strategies that improve reproductive performance in dairy and beef herd management practices.


• Factors that cause pregnancy loss in cattle and development of methods to reduce losses.

Data were generated using intramural and extramural competitive grant funds garnered by the members (more than $23 million). From 2017-2021, the group individually and collaboratively published refereed research papers (225), conference papers (70) theses and dissertations (50), book chapters and invited reviews (19), technical/extension publications (9), and deposited sequences into the Gene Expression Omnibus (14). Workshops and lectures (128) were also presented to producers, veterinarians, and consultants locally and internationally. In addition, to dissemination of the data, the findings were used to develop programs to improve synchronization of ovulation and to overcome environmental and nutritional factors that can disrupt reproduction. The group developed new management strategies and technologies to effectively use artificial insemination (AI) and embryo transfer (ET) technologies to improve reproductive performance and thereby immediately impact producers. Indeed, veterinarians, consultants, pharmaceutical companies, breed organizations, and companies serving animal industries benefitted from the work from this project. For example, collaborators have presented annual reports on the project to cattle AI organizations (Select Sires, Genex CRI, Alta Genetics), the National Association of Animal Breeders (NAAB), the American Association of Bovine Practitioners (AABP), dairy industry associations (Minnesota Dairy Association, Vermont Dairy Association), pharmaceutical and technology companies (Zoetis, Merck, Allflex), and extension education organization (PRO-Dairy).  In turn, those groups spread the technology to farm families/producers for implementation which benefits the on-farm profitability and sustains agricultural production systems that are highly competitive in the global economy.

Student training is another important impact of this project. The members of NE1727 (NY, IA, MS, OH, OR, PA, KY, MA, NE, TN, VT, WI, VA, and WV) developed a course on Contemporary Topics in Reproductive Biology to improve student understanding of the breadth of reproductive physiology including topics outside their primary area of research. Ninety-seven graduate students enrolled in this course during the last project period. This accounted for a majority of the 103 students who completed or are currently pursuing a M.S. or PhD across the experiment stations. Numerous undergraduate students with an interest in reproductive physiology were also introduced to investigative research. These activities represent an important contribution of the project to the education of the next generation of scientists, consultants, and other workers in animal agriculture industries.