The Faculty in Reproductive Biology at Illinois

Geoffrey E. Dahl

Animal Sciences
Ph.D., Michigan State University

To e-mail Dr. Dahl use: dahlg@mail.aces.uiuc.edu

Dr. Dahl maintains a website on the effects of photoperiod on milk production and other prodution characteristics in dairy cattle.

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 expression. 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.

Selected Publications:

Dahl, G.E., T.H. Elsasser, A.V. Capuco, R.A. Erdman and R.R. Peters. 1997. Effects of long daily photoperiod on milk yield and circulating insulin-like growth factor-1 (IGF-1). J. Dairy Sci. 80:2784-2789.

Miller, A.R.E., E.P. Stanisiewski, R.A. Erdman, L.W. Douglass and G.E. Dahl. 1999. Effects of long daily photoperiod and bovine somatotropin (Trobest®) on milk yield in cattle. J. Dairy Sci. 82:1716-1722

Dahl, G. E., B. A. Buchanan and H. A. Tucker. 2000. Photoperiodic effects on dairy cattle: A review. J. Dairy Sci. 83:885-893.

Miller, A.R.E., L.W. Douglass, R.A. Erdman and G.E. Dahl. 2000. Effects of photoperiodic manipulation during the dry period of dairy cows. J. Dairy Sci. 83:962-967

Dunlap, T.F., R.A. Kohn, D.E. Dahl, M. Varner, and R.A., Erdman. 2000. The impact of somatotroping, milking frequency, and photperiod on dairy farm nutrient flows. J. Dairy Sci. 83:968-976.

Auchtung T.L., D.A. Buchanan, C.A. Lents, S.M. Barao, and G.E. Dahl. 2001. Growth hormone response to growth hormone-releasing hormone in beef cows divergently selected for milk production. J. Anim. Sci. 79:1295-1300.

T. L. Auchtung, E. E. Connor, S. M. Barao, L. W. Douglass, and G. E. Dahl. 2001. Use of growth hormone response to growth hormone-releasing hormone to determine growth potential in beef heifers. J. Anim. Sci. 79:1566-1572.

Auchtung T.L., S.M. Barao, and G.E. Dahl. 2001. Relation of growth hormone response to growth hormone-releasing hormone before weaning and postweaning growth performance in beef calves. J. Anim. Sci. 79:2217-2223.

Last updated Aug. 25, 2001

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