• Ernst, Cathy (swine and bovine molecular genetics, growth biology, meat science)
• Hill, Gretchen (swine nutrition and management, mineral nutrition, animal health)
• Nielsen, Brian (equine exercise physiology, nutrition, athletic performance)
• Orth, Michael (joint and skeletal health, nutrition, diagnostics)
• Rozeboom, Dale (swine management and production systems, biosecurity)
• Trottier, Nathalie (swine nutrition, amino acid metabolism, mammary physiology)

Catherine W. Ernst, Associate Professor
Principal Investigator, Molecular Genetics Laboratory
Nancy Raney, Research Technician and Laboratory Coordinator

The overall goal of the Molecular Genetics Laboratory is to identify and evaluate molecular markers for the genetic improvement of pigs and beef cattle with emphasis on performance traits and carcass composition. Current research projects involve mapping and functional evaluation of genes and genetic markers in pigs and cattle, identification of differentially expressed genes in developing pig skeletal muscle, determination of nutritionally regulated gene expression patterns in pigs, and establishment of resource populations for identifying quantitative trait loci (QTL) for carcass merit and meat quality in pigs and beef cattle. A major emphasis area for the lab is comparative mapping of genes in the pig. Pig sequence-tagged sites (STS) are developed from human gene sequence and are placed on the INRA-University of Minnesota radiation hybrid map. These STS are also screened for the presence of single-nucleotide polymorphisms (SNPs), which are then used for linkage mapping on the international PiGMaP or USDA-MARC genetic maps. Another major research area involves identification of differentially expressed genes in developing pig skeletal muscle in order to better understand the mechanisms controlling skeletal muscle growth and development. Initial studies have utilized differential display PCR and cDNA microarray analysis, and further transcriptional profiling studies are planned in collaboration with Dr. Matt Doumit. Similar techniques are also being employed in a collaborative study with Dr. Gretchen Hill to identify genes regulated by zinc supplementation of nursery pigs. An F2 swine resource population involving an initial cross of Pietrain and Duroc animals is currently under development in collaboration with Dr. Ron Bates. DNA, tissues and extensive phenotypic records are being stored for each animal in the population and when completed, the population will be one of the largest in the world for performing QTL analyses in swine. An F2 population is also being developed for beef cattle with Angus and Limousin foundation animals in collaboration with Drs. Dennis Banks and Richard Pursley. In addition to numerous collaborations with MSU scientists, projects in the molecular genetics lab also involve collaborations with other university, USDA and international scientists, including a collaboration with scientists at the National Food Centre in Dublin, Ireland.

Gretchen Hill, Professor

Understanding the role of trace element nutrition in livestock from the basic nutrient utilization and conservation to the molecular basis is the encompassing goal of our laboratory. Our current research objectives are to:

• Determine the molecular role of pharmacological zinc in enhancing growth of the nursery pig
• Investigate cellular iron homeostasis in swine by determining the role of iron regulatory proteins
• Reduce the amount of trace elements excreted by livestock while maintaining efficient production
• Provide new insights on selenium needs of cows and their calves relative to thermo energy regulation and ultimately health
• Understand trace element interactions and their affect on health
• Determine status indicators and parameters that influence the trace element requirements of reproducing females in livestock herds

Brian D. Nielsen, Professor
Principal Investigator, Equine Exercise Physiology Laboratory
Cara O’Connor, Research Assistant

Dr. Nielsen heads the equine research program in the Department of Animal Science. Cara O’Connor, his research assistant, coordinates and manages the research laboratory and oversees many of the research projects. The primary focus of their research, conducted with graduate and undergraduate students, is aimed at improving the growth and development of the equine athlete, with special attention given to the prevention of musculoskeletal injuries. Much of their research examines the response of bone to mechanical loading and the lack thereof, and has been done not only with horses, but also with cattle and dogs. Furthermore, research on the effect of housing management on bone development in young horses has led to collaborative work in horse behavior and welfare. Many nutritional studies are conducted, particularly in the area of mineral nutrition, with special emphasis on bio-available silicon supplementation and its influence on animal health. The team has also put significant research efforts into the exploration of the special dietary needs of weanling and yearling horses in order to improve growth and prevent developmental orthopedic disorders. In addition to these primary areas, special projects explore the use of various ergogenic agents on performance enhancement in equine athletes.

Michael Orth, Associate Professor
Growth and Musculoskeletal Biology Laboratory

My research interests focus on improving joint and skeletal health in livestock species and companion animals. We have three primary interests at the present time. First, glucosamine and chondroitin sulfate are two nutraceutical products that have been reported to improve joint health in both animals and humans. Our objective is to elucidate the mechanisms of action of those compounds since how they work in vivo is not well understood. We also investigate other molecules as well that might promote joint health. Second, in conjunction with colleagues in Engineering, Osteopathic Medicine and Veterinary Medicine, we are continually striving to improve in vitro models for the study of cartilage degeneration. Third, we are interested in using biological fluid markers to monitor bone health in livestock species. We have conducted collaborative research projects in several livestock species. Many diagnostic tools developed for humans have tremendous potential in the livestock industry for evaluating strategies designed to improve bone health.

Dale W. Rozeboom, Professor

Our research activities are focused on generating information needed by swine producers in order to enhance their economic opportunities and in dealing with the increasing social and environmental pressures being placed on their businesses. Thus, our work is in the areas of nutrition, reproduction, behavior and the management of production systems. We are currently studying the environmental and biosecurity risks of animal tissue recycling using composting, the effect of pre-farrow feed intake on sow reproduction, sow response to varied feeder design in lactation and the use of dietary fiber to modify the growth pattern of pre-pubertal gilts.

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.