Successful and efficient reproduction is essential to food and fiber production from livestock and poultry. Numerous environmental factors compromise preproductive efficiency and increase unit cost of production. Periods of diminished gonadal activity reduce efficiency or production through added costs from maintaining reproductively inactive animals. Inefficiencies in collection, storage, sexing, and use of semen, oocytes, and embryos limit utilization and conservation of valuable germplasm. Sub-optimal embryonic, fetal, and neonatal development and survival significantly reduce efficiency and profitability. Complex and poorly understood relationships between endocrine, metabolic, and immune systems hinder development and implementation of improved systems for managing reproduction.
Produce reproductively efficient domestic livestock and poultry that require fewer resources, produce less waste, and supply animal products that more fully meet consumer expectations.
We seek to mitigate environmental conditions that reduce reproductive efficiency; enhance production of fertile gametes and survival of embryos, fetuses, and neonates; understand interactions between reproductive and immune systems; and ultimately achieve optimum reproductive rate per breeding female.
Decrease overhead and unit cost of production in all farm animal species, resulting in greater profitability for U. S. livestock producers and in lower food costs for consumers.
USDA-ARS National Programs: 103 Animal Health; and 105 Animal Well-Being and Stress Control Systems
Other Agencies and Departments: Other USDA Agencies and Universities: Howard University, Texas A and M University, Carroll College, Utah State University, University of Georgia, Oregon State University, Alcorn State University, Danbred USA, University of Nebraska.
Private sector: National Association of Animal Breeders, Monsanto Company, and the U.S. Poultry and Egg Association.
II. PROBLEMS TO BE ADDRESSED
Reproductive efficiency is affected by numerous environmental factors including temperature, humidity, photoperiod, nutrition, and non-specific stressors. Environmental factors are detected by higher brain centers which affect the neuro-endocrine system, subsequent pituitary hormone secretion, and secretion of other hormones. Environmental factors may also directly influence gonadal and uterine function and the conceptus. Managing the environment for optimum reproductive efficiency requires understanding basic neuro-endocrine regulatory mechanisms, gonadal and uterine function, and conceptus development. These systems may be further altered by other environmental factors including social interactions among animals, handling by humans, housing, and transportation.
1. Elucidate environmental influences on specific components of reproductive performance.
2. Mitigate environmental effects on critical control points limiting reproductive efficiency.
1. Determine how to mitigate the effects of environment on reproductive performance.
2. Determine environmental effects on neuro-endocrine pathways controlling adrenal, thyroid, and gonadal function, and behavior.
3. Determine direct environmental effects on fertilization, implantation, embryo survival, pregnancy, parturition, and egg production.
Management techniques and production systems that optimize reproductive efficiency by reducing negative environmental effects.
Athens, GA; Beltsville, MD; Brooksville, FL; Clay Center, NE; Dubois, ID; Miles City, MT .
Fertile Gamete Production
Prepubertal development, seasonally reduced gamete production, postpartum anestrus, and aging all represent periods of inefficiency in livestock and poultry. During prepubertal development the hypothalamus and pituitary are highly sensitive to suppressive factors primarily secreted by the gonads. During seasonal declines in gamete production or extended periods of dietary restriction, the reproductive axis is more sensitive to suppressive factors, many of which are produced in the brain or gonad. Opportunities exist to optimize economic returns by determining how to combine genetic and nutritional resources in a manner that reduces the duration of these periods of diminished gonadal activity that result in reproductive quiescence.
1. Optimize rate of sexual development and maximize efficiency of gamete production.
2. Lengthen reproductive longevity and minimize periods of gonadal inactivity.
1. Identify genes and gene products whose expression is differentially regulated in individual animals that have superior rates of gamete production.
2. Identify genes and gene products that are associated with enhanced gamete production, sub-optimal photoperiod stimulation, at puberty, following parturition, and at advanced ages.
1. Understand genetic regulation of pubertal development in livestock and poultry.
2. Increase efficiency of gamete production in aging animals.
3. Technologies to hasten and extend gamete production.
Athens, GA; Beltsville, MD; Brooksville, FL; Clay Center, NE; Dubois, ID; Miles City, MT.
Gamete and Embryo Storage, Sexing, Cryopreservation, and Use
Artificial insemination and embryo transfer extend longevity and use of superior germplasm many-fold. However, these technologies are labor intensive and in some species inefficient. New and commercially applicable methods for storage of sperm in liquid or frozen form could greatly enhance reproductive efficiency. New reproductive technologies can further increase the rate of genetic improvement and reduce costs of livestock and poultry production. New technology is also needed to efficiently mature, fertilize, and culture oocytes/embryos in vitro. Storage of embryos, oocytes, and somatic cells enables preservation of maternal genetic information and facilitates international trade in germ plasm.
1. Develop new and improved existing methods of cryogenic preservation of sperm, somatic cells, oocytes, and embryos for livestock and poultry, placing emphasis on hard to freeze species, breeds, or lines within breeds.
2. Improve methods for sex-preselection of sperm so that it can be used for conventional artificial insemination.
3. Improve in vitro maturation, fertilization, and culturing of oocytes and in vivo developmental competence of mammalian embryos after cryopreservation and embryo transfer.
1. Evaluate biological factors that impact sperm, oocyte and embryo survival after cryopreservation.
2. Develop freezing and thawing methods that improve fertility and survival of cryopreserved gametes and embryos.
3. Develop new technologies to improve reproductive efficiency.
1. Reliable methods for cryogenic preservation of sperm, oocytes and embryos.
2. Increased reproductive efficiency that expands use of superior germplasm.
Beltsville, MD; Brooksville, FL; Fort Collins, CO, Miles City, MT.
Embryo, Fetal, and Neonatal Development and Survival
Delays in establishing pregnancy increase cost and reduce output of food animal systems. Maximum production efficiency requires every fertilized egg to result in birth of a healthy offspring that survives and grows during the neonatal period. Factors contributing to embryonic and fetal losses and/or inappropriate development in domestic livestock are numerous and interacting. Incidence of embryonic and fetal mortality has been estimated to be 20 to 40% in livestock species and 10 to 14% in poultry. Others are born with extreme birth weights or other developmental abnormalities that contribute to loss during the neonatal period.
1. Prevent abnormal and inefficient embryonic, fetal, and neonatal growth and development in livestock and poultry species.
2. Mitigate abnormal development and growth of embryo, fetus, and neonate.
3. Improve embryonic, fetal, and neonatal survival and health.
1. Identify physiological mechanisms causing inappropriate development and loss in domestic livestock species during the embryonic, fetal and neonatal periods.
2. Develop methods to control physiological mechanisms resulting in inappropriate development and loss and to assess other consequences of these changes.
3. Modify, as needed, those procedures controlling physiological mechanisms resulting in inappropriate development and loss and disseminate appropriate technologies to the livestock industry.
1. Enhanced embryonic, fetal, and neonatal development and survival through modification of physiological mechanisms, and genetic selection.
2. Disseminate methodology to improve development of embryos, fetuses, and neonates.
3. Reduce inputs used to obtain healthy offspring.
Athens, GA; Beltsville, MD; Clay Center, NE; Dubois, ID; Miles City, MT
Interactions of Endocrine and Immune Systems
Complex interactions between immune and endocrine systems affect many physiological processes, including reproduction. Resolving basic mechanisms that control the many interactions between immune and endocrine systems is essential for improving growth and development, reproductive management, and production efficiency.
1. Elucidate the role of the immune system in modulating reproductive activity, mammary function, gametic production and survival, luteal function, pregnancy, uterine involution, and embryonic development in the female reproductive tract.
2. Improve uterine immune functions to reduce uterine and oviductal infections without using antibiotics.
1. Determine cellular and molecular mechanisms by which endocrine secretions regulate uterine immune functions allowing the uterus to eliminate or manage bacterial contamination.
2. Define cellular and molecular interactions affecting control of reproductive health and efficiency by endocrine and immune systems to influence the reproductive efficiency of both healthy and immune stressed animals.
3. Determine mechanisms of the immune system that regulate luteal function and gametic development, maturation, and survival in the female reproductive tract
1. New, effective methods for managing reproductive events.
2. Novel methods for preventing or treating uterine infection and bacterial contamination that do not rely on antibiotics.
3. Nutritional, genetic, environmental, and management strategies to promote immune functions that enhance reproductive efficiency
Athens, GA; Beltsville, MD; Brooksville, FL; Clay Center, NE; Dubois, ID