NE1027: Ovarian Influences on Embryonic Survival in Ruminants
Statement of Issues and Justification
The need as indicated by stakeholders. Impaired reproductive performance is a major cause of reduced productivity for ruminants and of reduced profitability for dairy and meat animal producers. The focus of the NE-1007 Regional Project (and its predecessor, the NE-161 Regional Project) has been to address nutritional, management, and environmental factors that impact ovarian activity and subsequent pregnancy rates in domestic ruminants. Our current goal is to continue this important investigative work, focusing on ovarian and embryonic aspects of infertility, and to seek renewal of this multistate effort.The objectives of this proposal are consistent with the first strategic goal identified in the CSREES Strategic Plan (2004-2009), which is to "Enhance economic opportunities for agricultural producers". Under objective 1.5 [Contribute science-based information, analysis, and education to promote the efficiency of agricultural production systems], we will evaluate our progress using performance criteria 1.5.7 [Increase and improve the reproductive performance of animals; CSREES problem area 301], 1.5.8 [Enhance the efficiency of nutrient utilization for animal productivity; CSREES problem area 302], and 1.5.11 [Improve understanding of fundamental animal physiological processes; CSREES problem area 305]. Moreover, at a recent workshop, a group of more than 75 stakeholder scientists from federal, public, and private institutions across the United States recommended the following high impact areas as funding priorities for USDA/CSREES: "development of the oocyte, follicle recruitment and development, identifying genes involved in gamete quality and embryo development, uterine-conceptus interactions with emphasis on embryonic and fetal survival, reproductive immunology, and gonadal development" (Mirando and Hamernik, 2006). Our stakeholders include animal producers, the scientific community, and citizens of the region and the nation.
Importance of work and consequences if it is not done. Improving fertility in ruminants requires fundamental knowledge about the influence of oocyte quality, follicular development, corpus luteum function, and uterine environment on embryonic survival. The determination of ovarian and embryonic attributes of fertility in ruminants is critical to identify the underlying causes of anovulation, fertilization failure, luteal insufficiency, and early embryonic loss. Further experimental manipulation of these identified attributes will lead to a prioritization of future studies and management strategies. By enhancing basic knowledge of the underlying biology surrounding ovarian function and embryonic survival, new strategies can be developed for application by producers and veterinarians. Application of management strategies that are not based upon drug-development or use of new drugs is economical, user and consumer friendly, and preserves food quality and safety.
The technical feasibility of the work. NE-1007 has historically been one of the most productive, cohesive, and diverse multistate research groups nationwide. Technical members of NE-1007 (molecular biologists, cell physiologists, and animal scientists) have demonstrated broad expertise in reproductive physiology of domestic ruminants, using a multistate, collaborative approach to accomplish project objectives. In the four previous years of this project, the eight technical members of NE-1007 have published over 65 refereed research papers, abstracts, theses, book chapters, and technical/extension publications. Accomplishments include: developed granulosal/luteal cell models to measure the effects of heat stress on steroidogenesis in vitro; provided evidence that retention of pregnancy in ruminants is associated with both maternal age and concentration of progesterone (P4) during placentation; devised an approach to measure genetic and physiologic changes in single oocytes and steroidogenic cells; demonstrated that moderately larger, not small preovulatory follicles and greater plasma estradiol concentrations on the day of AI increased the likelihood of subsequent pregnancy at day 29 in cattle; identified molecular and cellular mechanisms that influenced luteal function and resulted in embryonic/fetal mortality; formulated a method to assess allantoic development ultrasonographically to predict pregnancy outcome; and determined that nutritional and metabolic status during late pregnancy plays a pivotal role in the outcome of the first postpartum follicular wave.
The advantages for doing the work as a multistate effort. Advantages of performing this work as a multistate effort include overlapping approaches with collaborative efforts and technologies that can be directed toward several objectives simultaneously, and shared experience and data analyses that make interactions more beneficial. For example, members at different stations have contributed to unified animal protocols and exchange samples to take advantage of unique validated procedures and will continue to do so in this project. Moreover, the combination of basic biological research and innovative applied research more effectively supports outreach programs and engagement, the goal of which is to improve reproductive performance in livestock more rapidly. Likely impacts from successfully completing the work. Fulfilling the objectives of this project will provide important new information concerning declining fertility among ruminants in the face of continuous improvement in production capability. Impacts include improved understanding of how oocyte quality, follicular/luteal function, and metabolic demands of production may alter key hormonal or cellular signals necessary for oocyte competence, fertilization, and embryo survival in early pregnancy. Preventive or therapeutic approaches to treat infertility and embryonic loss will benefit consultants (Nutritionists, Veterinarians, Educators, etc) and most importantly animal producers. Improved animal reproductive performance benefits the on-farm economy and sustains an agricultural production system that is highly competitive in the global economy.
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