Exercise Physiology

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.

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.