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  Lactation Biology


Karen Plaut, Professor; and
Theresa Casey, Research Assistant Professor
Mammary Gland Biology Laboratory
Heather Dover, Research Technician

The overall objective of our research is to understand how cells, growth factors, hormones, organ systems and the environment interact to regulate mammary development and lactation. Presently our research is focused in two main areas: understanding the role of epithelial and stromal interactions in mammary development and neoplasia; and understanding how homeorhetic changes are coordinated among adipose, liver and mammary metabolism to prepare for and maintain lactation. We currently have two on-going projects focused on the stromal and epithelial interactions in mammary development. The first is focused on understanding the remodeling processes that occur in the mammary gland during the dry period in the dairy cow. The second project is focused on understanding the role that stromal fibroblast cells play in breast cancer invasion and metastasis. Our other major area of interest is studying the mechanisms involved in the homothetic changes in mammary, liver and adipose tissue metabolism necessary for a successful lactation. Dam metabolic activities are changed and coordinated among mammary, liver and adipose tissues through tightly controlled endocrine signals during the periparturient period that prepare for lactation and maintain homeostasis. Changes in metabolic activity result in the partitioning of dietary nutrients as well as the mobilization of stored energy from the liver and adipose tissues to the mammary gland for milk synthesis. Our overall objective is to develop a systems approach to analyze and model the homothetic changes that occur during the periparturient period in metabolism among mammary, liver and adipose tissue using biological data and developing multi-scale and multi-paradigm models of this system in collaboration with software engineers and mathematical modelers. Once developed these models will enable us to better understand the interdependencies among liver, mammary, and adipose tissues as they relate to healthy and disease states.

Nathalie L. Trottier, Associate Professor
Non-ruminant Nutrition Laboratory

The overall objective of my research program is to study factors affecting and regulating amino acid utilization in animals. To accomplish this objective, we have focused on three major areas. The first area is the estimation of amino acid requirements of non-ruminants species at different stages of production. In this area, my primary focus is lactation both in the pig and the horse. Our approach to determine amino acid requirements during lactation uses a combination of the traditional milk amino acid profile as well as mammary amino acid uptake profile. More recently, in collaboration with Drs. Brian Nielsen, John Shelle and Christine Skelly, I have begun testing various approaches to estimate protein requirements of the exercising horse. My second area of research involves the study of factors controlling the availability of amino acids for milk production. In this area we have examined aspects such as dietary protein intake, blood flow, and more recently, in collaboration with Dr. Jeanne Burton, whether amino acid transport processes pose a limitation on milk protein synthesis. To accomplish the later, we are using a combination of kinetic and molecular approaches to identify and characterize amino acid transport systems and proteins. We hope that the information generated will provide major advances in our understanding of the regulatory mechanisms for milk protein synthesis and the efficiency of amino acid utilization by the mammary gland. My third area of research focuses on the optimization of dietary amino acid utilization to lessen environmental nitrogen losses. Because nitrogen (N) and ammonium (NH4+) are major components of agricultural waste contributing to environmental pollution, the optimization of dietary amino acid utilization during growth or other productive functions has become one of my research priorities. There is discrepancy between studies on growth performance, body composition, and nitrogen status in animals fed reduced crude protein diets to limit nitrogen losses. We are currently focusing on identifying the factors that pose a limitation on dietary crude protein reduction. Better understanding of the dietary manipulations that can reduce nitrogen losses and maintain production efficiencies is needed to assist in designing nutrient management plans.

Michael J. VandeHaar, Professor
Ruminant Metabolism Laboratory
Jim Liesman, Research Associate

My research program includes dairy nutrition and mammary physiology, replacement heifer nutrition and management and nutrition modeling. The major research focus is to identify mechanisms by which nutrition alters mammary development of dairy heifers with emphasis on leptin and the insulin-like growth factor system.

Miriam S. Weber Nielsen, Assistant Professor
Ruminant Metabolism Laboratory
Larry Chapin, Research Technician

Our research program focuses on identifying hormonal and nutritional factors that regulate growth and development of the bovine mammary gland. The emphasis of our current work is on evaluating development of the mammary gland in growing heifers and in response to changes in nutritional management. The laboratory also conducts work to identify factors that regulate proliferation of mammary epithelial cells in vitro. Research involves a variety of techniques including cell culture, immunocytochemistry, RT-PCR, cDNA microarrays, Northern blotting, Western blotting, ELISA, radioimmunoassay and others. The overall goal of our research is to identify strategies to more efficiently raise and manage dairy heifers to be productive lactating cows.