James Oltjen, Ph.D.

Position Title

Professor Emeritus

2153 Meyer Hall

Education

B.S., Physics, Kansas State University, Manhattan, Kansas, 1975.
M.S., Animal Science, Kansas State University, Manhattan, Kansas, 1978.
Ph.D., Nutrition, University of California, Davis, California, 1983

Extension Interests

Computer decision support software.
Beef quality assurance.
Standardized performance analysis for cattle and sheep ranches.

Research Interests

Animal management systems.
Resource use in animal agriculture.
Beef cattle growth

Additional information about Dr. Oltjen's Research and Extension Programs

Graduate Groups

People

Current Graduate Students

Andres Gines, MS Program, Animal Biology Graduate Group. Expected Graduation Date: Spring 2021.
Meredith Harrison, PhD Program, Animal Biology Graduate Group. Expected Graduation Date: Spring 2023.
Sarah Klopatek, PhD Program, Animal Biology Graduate Group. Expected Graduation Date: Spring 2020.
Sheyenne Augenstein, MS Program, Animal Biology Graduate Group. Expected Graduation Date: Summer 2020

Selected Publications

Beckett, J.L. and J.W. Oltjen. 1993. Estimation of the water requirement for beef production in the United States. J. Anim. Sci. 71:818-826.

Ferrell, C.L. and J.W. Oltjen. 2008. ASAS CENTENNIAL PAPER: Net energy systems for beef cattle—concepts, application, and future models. Journal of Animal Science 86:2779-2794.

Hyer, J. C., J. W. Oltjen and M. L. Galyean. 1991. Development of a model to predict forage intake by grazing cattle. J. Anim Sci. 69:827-835.

McPhee, M. J., J. W. Oltjen, J. G. Fadel, D. Perry, and R. D. Sainz. 2008. Development and evaluation of empirical equations to interconvert between twelfth-rib fat and kidney, pelvic, and heart fat respective fat weights and to predict initial conditions of fat deposition models for beef cattle. J. Anim Sci. 86: 1984-1995.

McPhee, M.J., J.W. Oltjen, T.R. Famula and R.D. Sainz. 2006. Meta-analysis of factors affecting carcass characteristics of feedlot steers. Journal of Animal Science 84: 3143-3154.

Oltjen, J. W. and F. N. Owens. 1987. Beef cattle feed intake and growth: empirical Bayes derivation of the Kalman filter applied to a nonlinear dynamic model. J. Anim. Sci. 65:1362.

Oltjen, J. W. and W. N. Garrett. 1988. Effects of body weight, frame size and rate of gain on the composition of gain of beef steers. J. Anim. Sci. 66:1732.

Oltjen, J. W., A. C. Bywater, R. L. Baldwin and W. N. Garrett. 1986. Development of a dynamic model of beef cattle growth and composition. J. Anim. Sci. 62:86.

Oltjen, J. W., G. E. Selk, L. G. Burditt and R. E. Plant. 1990. Integrated expert system for culling management of beef cows. Comp. Elec. Agric. 4:333-341.

Oltjen, J.W. 2006. Animal agriculture and global food supply. In: Recent Advances in Animal Nutrition 2005 (P.C. Garnsworthy and J. Wiseman, Eds.) pp. 371-377. Nottingham University Press, Nottingham, UK.

Oltjen, J.W. 2007. Parameter estimation using Markov chain, Monte Carlo techniques. In: Mathematical Modeling in Nutrition and Agriculture (M.D. Hanigan, J.A. Novotny and C.L. Marstaller, Eds.) pp. 69-78. Blacksburg: Virginia Polytechnic Institute and State University.

Oltjen, J.W. and A. Ahmadi. 2013. Taurus: A ration formulation program for beef cattle. Nat. Sci. Educ. 42:145-159. Doi:10.4195/nse.2011.00003

Oltjen, J.W. and S.A. Gunter. 2015. Managing the herbage utilization and intake by cattle grazing rangelands. Animal Production Science 55:397-410.

Oltjen, J.W., A. Cannas, A., A.S. Atzori, L.O. Tedeschi, R.D. Sainz and D.G. Fox. 2010. Integration of the Small Ruminant Nutrition System and of the UC Davis sheep growth model for improved predictions. In: Energy and Protein Metabolism and Nutrition (G.M. Crovetto, Ed.) pp. 553-554. European Assoc. for Anim. Prod. Publ. No. 127.

Oltjen, J.W., D.J. Drake, A.B. Ahmadi, A.J. Romera, S.J.R. Woodward, L.N. Bennett, F. Haque and L.J. Butler. 2008. Management simulation tool for estimating value of individual identification of beef cattle. In: Proceedings of Western Sec. American Society of Animal Science 59:140-141.

Oltjen, J.W., L.C. Forero and J.W. Stackhouse. 2017. Decision making tools: BeefTracker mobile app for tracking and analysis of beef herd pasture use and location. Translational Animal Science 1:250-254.

Oltjen, J.W., R.D. Sainz, A.B. Pleasants, T.K. Soboleva and V.H. Oddy. 2006. Representation of fat and protein gain at low levels of growth and improved prediction of variable maintenance requirement in a ruminant growth and composition model. In: Nutrient Digestion and Utilization in Farm Animals: Modelling Approaches (E. Kebreab, J. Dijkstra, A. Bannink, W.J.J. Gerrits and J. France, Eds.) pp. 144-159. CAB International, Wallingford, UK.

Oltjen, J.W., R.D. Sainz, L.G. Barioni and S.R. Medeiros. 2016. Rate of protein growth and energy for maintenance parameter changes in the Davis Growth Model. In: Energy and Protein Metabolism and Nutrition (J. Skomial and H. Lapierre, Eds.) pp. 69-70. European Assoc. for Anim. Prod. Publ. No. 137.

Renquist, B.J., J.W. Oltjen, R.D. Sainz, J.M. Connor and C.C. Calvert. 2005. Effects of supplementation and stocking rate on body condition and production parameters of multiparous beef cows. Animal Science 81:403-411.

Sainz, R.D., F. De la Torre and J.W. Oltjen. 1995. Compensatory growth and carcass quality in growth-restricted and refed beef steers. Journal of Animal Science 73:2971-2979.

Stackhouse, K.R., C.A. Rotz, J.W. Oltjen and F.M. Mitloehner. 2012. Growth-promoting technologies decrease the carbon footproint, ammonia emissions, and costs of California beef production systems. J. Anim. Sci. 90:4656-4665.

Stackhouse-Lawson, K.R., C.A. Rotz, J.W. Oltjen and F.M. Mitloehner. 2012. Carbon footprint and ammonia emissions of California beef production systems. J. Anim. Sci. 90:4641-4655.