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Kristen Johnson SF6Technique.pdf |
RUMINANT NUTRITION/BEEF CATTLE ENERGETICS. The focus of our research is to examine the use of dietary energy in the beef animal. This includes examination of the variation in maintenance energy expenditures and losses due to the fermentation occurring in the rumen. With up to 70% of total herd metabolizable energy intake going to maintenance functions, it is important to understand and examine the constituents of maintenance on a whole animal and cellular level and the relationship of these metabolic costs to animal productivity. Selection of adaptable cattle will reduce the cost of production. Current projects include an examination of the variation in maintenance requirements of three breeds of cattle at the whole animal, mitochondrial and gene level.
RUMINANTS AND ENVIRONMENTAL ISSUES. Environmental issues are of increasing concern to the cattle industry. Our goal is to generate scientifically based information about air quality and ruminant production. Recent projects include the development of a measurement-based methane inventory and efforts to find economically sound mitigation options for cattle producers. Ammonia emissions is a new area in which cattle producers will likely be faced with regulation. We have developed a technique by which ammonia emissions may be measured and are now looking at mitigation strategies.
Selected Publications:
- Johnson, K.A., R. L. Kincaid, H. Westberg, B. Lamb, C. Gaskins, J. Cronrath. 2002. Effect of oilseeds in diets of lactating cows on milk production and methane emissions. J. Dairy Sci. 85:1509-1515.
- Mount, G.H., R. Rumberg, B. Lamb, H. Westberg, D. Yonge, K. Johnson and R. Kincaid. 2002. Measurement of atmospheric ammonia at a dairy using differential optical absorption spectroscopy in the mid-ultraviolet. Atmospheric Environment. 36:1799-1810.
- Awadeh, F.T., R.L. Kincaid, and K.A. Johnson. 1998. Effect of level and source of dietary selenium on concentrations of thyroid hormones and immunoglobulins in beef cows and calves. J. Anim. Sci. 76:1204-1215.
- Harting, M.A., D.M. de Avila, K.A. Johnson and J.J. Reeves. 1997. Late-gestation treatment of pregnant cows with trenbolone acetate does not increase subsequent growth of heifer calves. J. Anim. Sci. 75:1190-1194.
- Xie, Y.R., J.R. Busboom, C.T. Gaskins, K.A. Johnson J.J. Reeves, R.W. Wright Jr. and J.D. Cronrath. 1996. Effects of breed and sire on carcass characteristics and fatty acid profiles of crossbred Wagyu and Angus steers. Meat Sci. 43:167-177.
- Ramsey, J.J., D.E. Johnson, K.L. Hossner and K.A. Johnson. 1996. Metabolic rate, organ mass, and mitochondrial proton leak variations in lean and obese rats. Comp. Biochem. Physiol. 113B:461-466.
- Boylston, T.D., S.A. Morgan, K.A. Johnson, J.R. Busboom, R.W. Wright, Jr. and J.J. Reeves. 1995. Lipid content and composition of Wagyu and domestic breeds of beef. J. Agric. Food Chem. 43:1202-1207.
- Johnson, K.A. and D.E. Johnson. 1995. Methane emissions from cattle. J. Anim. Sci. 73:2483-2492.
- Johnson, K.A., M.T. Huyler, H.H. Westberg, B.K. Lamb and P. Zimmerman. 1993. Measurement of methane emissions from ruminant livestock using a SF6 tracer technique. Environ. Sci. and Tech. 28:259.
- Carmean, B.R., K.A. Johnson, D.E. Johnson and L.W. Johnson. 1992. Maintenance energy requirements of the llama. Amer. J. Vet. Res. 53:1696-1698.
- Hotovy, S.K., K.A. Johnson, D.E. Johnson, G.E. Carstens and R.M. Bourden. 1991. Variation among beef cattle twins in maintenance energy requirements. J. Anim. Sci. 69:940-946.
- Rikhardsson, G., K.A. Johnson and D.E. Johnson. 1991. Effects of cimaterol on energetics and carcass characteristics of Suffolk ewe lambs. J. Anim. Sci. 69:396-404.
- Johnson, D.E., K.A. Johnson and R.L. Baldwin. 1990. Changes in liver and gastrointestinal tract energy demands in response to physiological workload. J. Nutr. 120:649-655.