Research Topics
Department of Animal Science
Ph.D. (1991) Michigan State University
Research Topics
- Environmental effects on endocrine systems
Research Interests
The focus of research in my laboratory is the impact of environment on endocrine control of lactation and growth in ruminants. Specifically, we are interested in photoperiodic effects on lactation and growth in cattle. Previously we determined that the galactopoietic effects of long day photoperiod is associated with increased insulin-like growth factor-I (IGF-I) secretion, yet long days have no effect on growth hormone (GH) secretion or IGF-binding protein activity. Also, melatonin patterns that mimic those of animals exposed prevent the long day-induced increase in IGF-I. Those findings have led to the hypothesis that photoperiod influences hepatic GH receptor activity, and we are currently examining the effect of long days on liver specific GH receptor expression.
A second area of research interest is the influence of photoperiod on immune function. Relative to short days, long day photoperiod dramatically increases secretion of IGF-I and prolactin, two hormones that also affect lymphocyte function in many species. We are currently determining if prolactin receptors are expressed on various leukocyte populations in cattle, and if circulating prolactin concentrations influence receptor expressions. More complete understanding of the effect of environment on the endocrine systems that control growth, lactation and immune function should lead to improvements in animal health and production efficiency.
Key Words Photoperiod, neuroendocrine, growth factors, lactation, growth
Current Research Funding USDA - BARD, C-FAR