NUTRITION AND METABOLISM IN RUMINANTS
Gerald B. Huntington
The overall objective of research conducted in my laboratory is to describe and quantify acquisition of nutrients and subsequent metabolism of nutrients by ruminants. I focus on beef cattle fed forages, but will use goats, sheep, or dairy cattle if required by the objectives of the research.
DESCRIPTION OF ONGOING RESEARCH
N metabolism in forage-fed ruminants. This work depends on collaboration with Dr. Matt Poore, an animal scientist with interest use of co-products and by-products as ruminant feedstuffs, and Dr. Joe Burns, an agronomist with specializiation in warm-season, perennial grasses. The main approaches or techniques include measures of ad libitum intake, in vivo and in vitro digestibility, nitrogen balance, and in vivo urea kinetics measured by infusion of 15,15N-urea and collection of tissues and excreta to calculate urea entry rate, urea recyclihg to the gastrointestinal tract, and multiple passes of dietary N through the animals’ urea pool.
Treatments in these studies focus on forage type (species), nutrient composition, and interaction of forages with supplements designed to improve ruminal fermentation and microbial protein production.
Production efficiency of beef cattle. This work is being done in collaboration with Drs. Matt Poore, Scott Whisnant, Joe Cassady, and Wes Snyder, members of a multidisciplinary team of nutritionists, physiologists, geneticists, and electrical engineers. The team is using registered Angus beef cattle from the Upper Piedmont Research Center in Reidsville, NC. Bulls and heifers (and eventually, cows) from that herd are used in studies of residual feed intake as well as other measures of production efficiency. The team is building a comprehensive database that includes information on individual animals’ genome, endocrine profile, eating and social behavior, feed intake and growth rate, and body composition, and heat loss. Studies with yearling bulls and heifers is underway.
Huntington, G.B., M. Poore, B. Hopkins, and J. Spears. 2001. Effect of ruminal protein degradability on growth and N metabolism in growing beef steers. J. Anim. Sci. 79:533-541.
Archibeque, S.L., G.B,Huntington, and J.C. Burns. 2001. Urea flux in beef steers: Effects of forage species and nitrogen fertilization. J. Anim. Sci. 79:1937-1943.
Bauer, M.L., Harmon, D. L., Bohnert, D. W., Branco, A. F., and Huntington, GB. 2001. Influence of "-linked glucose on sodium-glucose cotransport activity along the small intestine in cattle. J. Anim. Sci. 79:1917-1924.
Bauer, M.L., Harmon, D. L., McLeod, K., and Huntington,G. B. 2001. Influence of ?-linked glucose on sodium-glucose cotransport activity in ruminants. Comp. Biochem. Physiol. A 129:577-583.
Theurer, C.B, Huntington,G.B.,Huber,J. T.,Swingle, R. S., and Moore, J. A. 2002. Net absorption and utilization of nitrogenous compounds across ruminal, intestinal, and hepatic tissues of growing beef steers fed dry-rolled or steam-flaked sorghum grain. J. Anim. Sci. 80:525-532.
Lloyd, K.E., Whisnant, C.S., Huntington, G.B., and Spears, J.W. 2002. Effects of calcium salts of long-chain fatty acids on growth, reproductive performance, and hormonal and metabolite concentrations in pubertal beef heifers and postpartum cows. Prof. Anim. Sci. 18:66-73.
Archibeque, S.L., Huntington,G.B, and Burns, J.C. 2002. Nitrogen metabolism of beef steers fed endophyte-free tall fescue hay: Effects of ruminally protected methionine supplementation. J. Anim. Sci. 80:1344-1351.
Richards, C.J., Branco, A.F., Bohnert, D.W., Huntington, G.B., Macari, M., and Harmon, D.L. 2002. Intestinal starch disappearance increased in steers abomasally infused with starch and protein. J. Anim. Sci. 80:3361-3368.
Richards, C.J., Swanson, K. C., Paton, S. J., Harmon, D.L., and Huntington, G.B. 2003. Pancreatic exocrine secretion in steers infused postruminally with casein and cornstarch. J. Anim. Sci. 81:1051-1056.
Hill, S. R., B. A. Hopkins, S. Davidson, S. M. Bolt, D.E. Diaz, C. M. Brownie, T. Brown, G. B. Huntington, and L. M. Whitlow. 2004. Technical note: Techniques for dissection and analysis of the rumen in young calves. J. Dairy Sci. 88:324-326.
Matthews, A.K., Poore, M.H., Huntington, G.B. and Green, J.T. 2005. Intake, digestion, and N metabolism in steers fed endophyte-free, ergot alkaloid-producing endophyte-infected, or nonergot alkaloid-producing endophyte-infected fescue hay. J. Anim. Sci. 83:1179-1185.
Magee, K.J., Poore, M.H., Burns, J.C. and Huntington,G.B. 2005. Nitrogen metabolism in beef steers fed gamagrass or orchardgrass hay with or without a supplement. Can. J. Anim. Sci. 85:107-109.
Huntington, G.B., D. L. Harmon, and C.J. Richards. 2006. Sites, rates, and limits of starch digestion and glucose metabolism in growing cattle. J. Anim. Sci. 84:E14-E24.