Jerry Wayne Spears

Impact of Forrest H. Nielsen on my Career

Spears, J. W. (2026, January 24). Biological Trace Element Research.

Review: History of chromium in animal nutrition in the United States

Spears, J. W. (2025, March 25). Applied Animal Science.

The Effects of Trace Mineral Source, Diet Type, and Monensin and Tylosin on Rumen Fermentation Characteristics in Beef Cattle

Graziella, J. O., Loh, H. Y., Muco, C., Heldt, J. S., Spears, J. W., & Engle, T. E. (2025, June 22). Biological Trace Element Research.

Trace Mineral Source Impacts Volatile Fatty Acid Profile and Rumen Trace Mineral Solubility in Feedlot Steers

Loh, H. Y., Guimaraes, O., Thorndyke, M. P., Jalali, S., Spears, J. W., Heldt, J. S., & Engle, T. E. (2025, April 30). Animals.

16 Overview of trace minerals and considerations in defining their requirements

Spears, J. W. (2024, September 1). Journal of Animal Science.

22 Effects of trace mineral source and chromium propionate supplementation on rumen fermentation, growth performance, and carcass characteristics in finishing beef steers

Heldt, J. S., Loh, H. Y., Spears, J. W., Lloyd, K., & Engle, T. E. (2024, September 1). Journal of Animal Science.

25 Copper, manganese, and zinc source and concentration in free-choice mineral supplements influence production throughout three cow-calf production cycles

Farmer, C. G., Engle, T. E., Spears, J. W., & Heldt, J. S. (2024, September 1). Journal of Animal Science.

PSVII-25 The influence of trace mineral source on in vitro trace mineral solubility and trace mineral concentrations of rumen microorganisms in canulated steers fed a diet formulated for lactating dairy cows

Loh, H. Y., Spears, J., Gibbons, A., Quevedo, A., Guimaraes, O., Miller, A. C., … Engle, T. E. (2024, September 1). Journal of Animal Science.

Trace Mineral Source Influences Trace Mineral Solubility in Water and Mineral Binding Strength to Ruminal Digesta

Loh, H. Y., Spears, J. W., Guimaraes, O., Miller, A. C., Thorndyke, M. P., Thomas, T. A., & Engle, T. E. (2024, July 30). Biological Trace Element Research.

Trace mineral source and chromium propionate supplementation affect performance and carcass characteristics in feedlot steers

Spears, J. W., Loh, H. Y., Lloyd, K. E., Heldt, J. S., & Engle, T. E. (2024, January 1). Journal of Animal Science.

Trace mineral sources influence in vitro fermentation characteristics and trace mineral solubility

Loh, H. Y., Spears, J. W., Guimaraes, O., Miller, A. C., Thomas, T. A., & Engle, T. E. (2024, January 1). Journal of Animal Science.

Chromium propionate in turkeys: effect on performance and animal safety

Spears, J. W., Lloyd, K. E., Flores, K., Krafka, K., Hyda, J., & Grimes, J. L. (2023, October 14). Poultry Science.

Chromium propionate in turkeys: effects on insulin sensitivity

Spears, J. W., Lloyd, K. E., Krafka, K., Hyda, J., & Grimes, J. L. (2023, October 18). Poultry Science.

Evaluation of Trace Mineral Sources

Spears, J. W. (2023, July 6). Veterinary Clinics of North America Food Animal Practice.

PSV-12 The Influence of Trace Mineral Source on Rumen Trace Mineral Solubility and In-Vitro Fiber Digestion in Steers Fed a Lactating Dairy Diet

Loh, H. Y., Mezzomo, R., Gomes, D. I., Tangredi, B. V., Guimaraes, O., Gifford, R. J., … Engle, T. E. (2023, November 6). Journal of Animal Science.

Research Note: Chromium propionate for turkeys: effect on tissue chromium concentrations and human food safety

Spears, J. W., Lloyd, K. E., Krafka, K., Hyda, J., & Grimes, J. L. (2023, October 14). Poultry Science.

Dietary copper supplementation modulates performance and lipid metabolism in meat goat kids

ZHANG, Y.-mei, De, A. O., Kai-wen, L. E. I., SPEARS, J. W., Hai-tao, S. H. I., HUANG, Y.-ling, & YANG, F.-long. (2022, August 10). Journal of Integrative Agriculture.

Invited Review: Assessing trace mineral status in ruminants, and factors that affect measurements of trace mineral status

Spears, J. W., Brandao, V. L. N., & Heldt, J. (2022, May 30). Applied Animal Science.

Trace mineral source influences digestion, ruminal fermentation, and ruminal copper, zinc, and manganese distribution in steers fed a diet suitable for lactating dairy cows

Guimaraes, O., Wagner, J. J., Spears, J. W., Brandao, V. L. N., & Engle, T. E. (2022, March 26). Animal.

Effects of supplemental zinc on ruminal fermentation in continuous cultures

Applied Animal Science, 37(1), 27–32.

Trace mineral source impacts rumen trace mineral metabolism and fiber digestion in steers fed a medium-quality grass hay diet

Guimaraes, O., Jalali, S., Wagner, J. J., Spears, J. W., & Engle, T. E. (2021, September 1). Journal of Animal Science.

105 Chromium propionate improves insulin sensitivity in horses following oral concentrate consumption

Spears, J. W., Siciliano, P., Pratt-Phillips, S., Lloyd, K., Goertzen, E., Krafka, K., … Rounds, W. (2020, November 3). Journal of Animal Science, Vol. 98, pp. 88–88.

139 Ruminal microbiota mineral requirements to optimize performance on different diets

Spears, J. W. (2020, November 2). Journal of Animal Science.

226 Influence of trace mineral source on digestion, ruminal volatile fatty acid and soluble mineral on steers fed a dairy type diet balanced to meet requirements for a high producing lactating dairy cow

Guimaraes, O., Wagner, J., Spears, J., & Engle, T. (2020, November 2). Journal of Animal Science.

Chromium propionate increases insulin sensitivity in horses following oral and intravenous carbohydrate administration

Spears, J. W., Lloyd, K. E., Siciliano, P., Pratt-Phillips, S., Goertzen, E. W., McLeod, S. J., … Rounds, W. (2020, March 25). Journal of Animal Science, Vol. 98.

Influence of supplemental copper, manganese, and zinc source on reproduction, mineral status, and performance in a grazing beef cow-calf herd over a 2-year period

Jalali, S., Lippolis, K. D., Ahola, J. K., Wagner, J. J., Spears, J. W., Couch, D., & Engle, T. E. (2020, September 28). Applied Animal Science.

PSXII-13 The influence of trace mineral source on copper, manganese, and zinc binding strength to rumen digesta in cattle fed a high forage-based diet

Guimaraes, O., Loh, H. Y., Thorndyke, M. P., Tillquist, N. M., Spears, J. W., & Engle, T. E. (2020, November 3). Journal of Animal Science.

PSXII-14 The influence of trace minerals source on copper, manganese, and zinc binding strength to rumen digesta in cattle fed a corn silage-based diet

Guimaraes, O., Loh, H. Y., Thorndyke, M. P., Tillquist, N. M., Spears, J. W., & Engle, T. E. (2020, November 3). Journal of Animal Science.

Research Note: Responses of growth performance, immune traits, and small intestinal morphology to dietary supplementation of chromium propionate in heat-stressed broilers

Poultry Science, 99(10), 5070–5073.

Chromium propionate in broilers: human food and broiler safety

Poultry Science, 98(12), 6579–6585.

Effect of zinc source and concentration and chromium supplementation on performance and carcass characteristics in feedlot steers1,2,3

Budde, A. M., Sellins, K., Lloyd, K. E., Wagner, J. J., Heldt, J. S., Spears, J. W., & Engle, T. E. (2019, January 10). Journal of Animal Science.

Trace mineral source influences ruminal distribution of copper and zinc and their binding strength to ruminal digesta1,2,3

Caldera, E., Weigel, B., Kucharczyk, V. N., Sellins, K. S., Archibeque, S. L., Wagner, J. J., … Engle, T. E. (2019, February 19). Journal of Animal Science.

Boron, Chromium, Manganese, and Nickel in Agricultural Animal Production

Spears, J. W. (2018, September 26). Biological Trace Element Research.

Bioavailability of zinc hydroxychloride relative to zinc sulfate in growing cattle fed a corn-cottonseed hull-based diet

Shaeffer, G. L., Lloyd, K. E., & Spears, J. W. (2017, July 29). Animal Feed Science and Technology.

Chromium concentrations in ruminant feed ingredients

Spears, J. W., Lloyd, K. E., & Krafka, K. (2017, February 23). Journal of Dairy Science.

Chromium propionate in broilers: effect on insulin sensitivity

Brooks, M. A., Grimes, J. L., Lloyd, K. E., Krafka, K., Lamptey, A., & Spears, J. W. (2016, March 1). Poultry Science.

Dietary Iron Deficiency and Oversupplementation Increase Intestinal Permeability, Ion Transport, and Inflammation in Pigs

Li, Y., Hansen, S. L., Borst, L. B., Spears, J. W., & Moeser, A. J. (2016, June 30). Journal of Nutrition, Vol. 146, pp. 1499–1505.

Effects of Supplemental Chromium Propionate on Serum Lipids, Carcass Traits, and Meat Quality of Heat-Stressed Broilers

Biological Trace Element Research, 176(2), 401–406.

History of chromium and its relationship to glucose metabolism

2016 Cornell Nutrition Conference for Feed Manufacturers, 1–8.

Effect of dietary copper amount and source on copper metabolism and oxidative stress of weanling pigs in short-term feeding1

Huang, Y. L., Ashwell, M. S., Fry, R. S., Lloyd, K. E., Flowers, W. L., & Spears, J. W. (2015, May 29). Journal of Animal Science, Vol. 93, pp. 2948–2955.

Bioavailability in chicks of zinc from zinc propionate

Brooks, M. A., Grimes, J. L., Lloyd, K. E., Verissimo, S., & Spears, J. W. (2013, May 17). The Journal of Applied Poultry Research.

Effect of copper on performance, carcass characteristics, and muscle fatty acid composition of meat goat kids

Journal of Animal Science, 91(10), 5004–5010.

Effects of quaternary benzo(c)phenanthridine alkaloids on growth performance, shedding of organisms, and gastrointestinal tract integrity in pigs inoculated with multidrug-resistant Salmonella spp

Robbins, R. C., Artuso-Ponte, V. C., Moeser, A. J., Morrow, W. E. M., Spears, J. W., & Gebreyes, W. A. (2013, November 25). American Journal of Veterinary Research.

Amount and source of dietary copper affects small intestine morphology, duodenal lipid peroxidation, hepatic oxidative stress,and mRNA expression of hepatic copper regulatory proteins in weanling pigs1,2

Fry, R. S., Ashwell, M. S., Lloyd, K. E., O'Nan, A. T., Flowers, W. L., Stewart, K. R., & Spears, J. W. (2012, May 15). Journal of Animal Science, Vol. 90, pp. 3112–3119.

Chromium propionate enhances insulin sensitivity in growing cattle

Spears, J. W., Whisnant, C. S., Huntington, G. B., Lloyd, K. E., Fry, R. S., Krafka, K., … Hyda, J. (2012, March 26). Journal of Dairy Science.

Effect of dietary copper and breed on gene products involved in copper acquisition, distribution, and use in Angus and Simmental cows and fetuses1,2

Fry, R. S., Spears, J. W., Lloyd, K. E., O'Nan, A. T., & Ashwell, M. S. (2012, November 13). Journal of Animal Science, Vol. 91, pp. 861–871.

Relative bioavailability in chicks of manganese from manganese propionate

Brooks, M. A., Grimes, J. L., Lloyd, K. E., Valdez, F., & Spears, J. W. (2012, February 20). The Journal of Applied Poultry Research.

Tolerance of cattle to increased dietary sulfur and effect of dietary cation-anion balance

Spears, J. W., Lloyd, K. E., & Fry, R. S. (2011, March 8). Journal of Animal Science.

Ctr1 Is an Apical Copper Transporter in Mammalian Intestinal Epithelial Cells in Vivo That Is Controlled at the Level of Protein Stability

Nose, Y., Wood, L. K., Kim, B.-E., Prohaska, J. R., Fry, R. S., Spears, J. W., & Thiele, D. J. (2010, August 11). Journal of Biological Chemistry.

Effect of dietary boron on physiological responses in growing steers inoculated with bovine herpesvirus type-1

Fry, R. S., Brown, T. T., Lloyd, K. E., Hansen, S. L., Legleiter, L. R., Robarge, W. P., & Spears, J. W. (2010, May 21). Research in Veterinary Science.

Effects of supplementing dairy cows with chromium propionate on milk and tissue chromium concentrations

Lloyd, K. E., Fellner, V., McLeod, S. J., Fry, R. S., Krafka, K., Lamptey, A., & Spears, J. W. (2010, September 20). Journal of Dairy Science, Vol. 93, pp. 4774–4780.

High dietary iron reduces transporters involved in iron and manganese metabolism and increases intestinal permeability in calves

Hansen, S. L., Ashwell, M. S., Moeser, A. J., Fry, R. S., Knutson, M. D., & Spears, J. W. (2010, February 1). Journal of Dairy Science, Vol. 93, pp. 656–665.

Investigation of breed and sex effects on cytochrome P450 gene expression in cattle liver

Ashwell, M. S., Fry, R. S., Spears, J. W., O’Nan, A. T., & Maltecca, C. (2010, June 17). Research in Veterinary Science, Vol. 90, pp. 235–237.

Age and Dietary Iron Affect Expression of Genes Involved in Iron Acquisition and Homeostasis in Young Pigs

Hansen, S. L., Trakooljul, N., Spears, J. W., & Liu, H.-C. (2009, December 17). Journal of Nutrition.

Bioaccessibility of iron from soil is increased by silage fermentation

Hansen, S. L., & Spears, J. W. (2009, May 15). Journal of Dairy Science.

Effect of dietary boron on immune function in growing beef steers*

Fry, R. S., Lloyd, K. E., Jacobi, S. K., Siciliano, P. D., Robarge, W. P., & Spears, J. W. (2009, March 31). Journal of Animal Physiology and Animal Nutrition, Vol. 94, pp. 273–279.

Effects of water quality and dietary potassium on performance and carcass characteristics of yearling steers1,2,3

Sexson, J. L., Wagner, J. J., Engle, T. E., & Spears, J. W. (2009, September 12). Journal of Animal Science.

Iron Transporters Are Differentially Regulated by Dietary Iron, and Modifications Are Associated with Changes in Manganese Metabolism in Young Pigs

Hansen, S. L., Trakooljul, N., Liu, H.-C., Moeser, A. J., & Spears, J. W. (2009, June 18). Journal of Nutrition.

Proteins involved in iron metabolism in beef cattle are affected by copper deficiency in combination with high dietary manganese, but not by copper deficiency alone1

Hansen, S. L., Trakooljul, N., Liu, H.-C. S., Hicks, J. A., Ashwell, M. S., & Spears, J. W. (2009, October 10). Journal of Animal Science, Vol. 88, pp. 275–283.

Technical note: Copper chaperone for copper, zinc superoxide dismutase: A potential biomarker for copper status in cattle1

Hepburn, J. J., Arthington, J. D., Hansen, S. L., Spears, J. W., & Knutson, M. D. (2009, August 28). Journal of Animal Science.

Copper deficiency in the young bovine results in dramatic decreases in brain copper concentration but does not alter brain prion protein biology1,2

Legleiter, L. R., Spears, J. W., & Liu, H. C. (2008, July 3). Journal of Animal Science.

Interaction of Calcium and Phytate in Broiler Diets. 1. Effects on Apparent Prececal Digestibility and Retention of Phosphorus

Poultry Science, 87(3), 449–458.

Role of antioxidants and trace elements in health and immunity of transition dairy cows

The addition of high manganese to a copper-deficient diet further depresses copper status and growth of cattle

Hansen, S. L., Ashwell, M. S., Legleiter, L. R., Fry, R. S., Lloyd, K. E., & Spears, J. W. (2008, September 8). British Journal Of Nutrition, Vol. 101, pp. 1068–1078.

Uptake of zinc from zinc sulfate and zinc proteinate by ovine ruminal and omasal epithelia1,2

Wright, C. L., Spears, J. W., & Webb, K. E. (2008, March 1). Journal of Animal Science.

Bioavailability of copper from copper glycinate in steers fed high dietary sulfur and molybdenum1,2

Hansen, S. L., Schlegel, P., Legleiter, L. R., Lloyd, K. E., & Spears, J. W. (2007, October 3). Journal of Animal Science.

Effects of Dietary Metabolizable Energy and Protein on Early Growth Responses of Broilers to Dietary Lysine

Poultry Science, 86(12), 2639–2648.

Effects of tribasic copper chloride versus copper sulfate provided in corn-and molasses-based supplements on forage intake and copper status of beef heifers1

Arthington, J. D., & Spears, J. W. (2007, February 12). Journal of Animal Science.

Exposure to low dietary copper or low copper coupled with high dietary manganese for one year does not alter brain prion protein characteristics in the mature cow1,2

Legleiter, L. R., Liu, H. C., Lloyd, K. E., Hansen, S. L., Fry, R. S., & Spears, J. W. (2007, October 22). Journal of Animal Science.

Plasma diamine oxidase: A biomarker of copper deficiency in the bovine1,2

Legleiter, L. R., & Spears, J. W. (2007, August 13). Journal of Animal Science.

Decreased brain copper due to copper deficiency has no effect on bovine prion proteins

Legleiter, L. R., Ahola, J. K., Engle, T. E., & Spears, J. W. (2006, December 2). Biochemical and Biophysical Research Communications.

Effects of a slow-release urea source on absorption of ammonia and endogenous production of urea by cattle

Huntington, G. B., Harmon, D. L., Kristensen, N. B., Hanson, K. C., & Spears, J. W. (2006, February 22). Animal Feed Science and Technology.

Feeding a Low Manganese Diet to Heifers During Gestation Impairs Fetal Growth and Development

Hansen, S. L., Spears, J. W., Lloyd, K. E., & Whisnant, C. S. (2006, November 1). Journal of Dairy Science.

Growth, reproductive performance, and manganese status of heifers fed varying concentrations of manganese1,2

Hansen, S. L., Spears, J. W., Lloyd, K. E., & Whisnant, C. S. (2006, November 8). Journal of Animal Science.

Influence of cobalt concentration on vitamin B12 production and fermentation of mixed ruminal microorganisms grown in continuous culture flow-through fermentors1

Tiffany, M. E., Fellner, V., & Spears, J. W. (2006, March 1). Journal of Animal Science, Vol. 84, pp. 635–640.

Differential responses to dietary cobalt in finishing steers fed corn-versus barley-based diets1

Tiffany, M. E., & Spears, J. W. (2005, November 1). Journal of Animal Science.

Effect of chromium supplementation and copper status on glucose and lipid metabolism in Angus and Simmental beef cows

Stahlhut, H. S., Whisnant, C. S., Lloyd, K. E., Baird, E. J., Legleiter, L. R., Hansen, S. L., & Spears, J. W. (2005, December 16). Animal Feed Science and Technology.

Effect of chromium supplementation and copper status on performance and reproduction of beef cows

Stahlhut, H. S., Whisnant, C. S., & Spears, J. W. (2005, December 16). Animal Feed Science and Technology.

Influence of dietary manganese on performance, lipid metabolism, and carcass composition of growing and finishing steers1,2

Legleiter, L. R., Spears, J. W., & Lloyd, K. E. (2005, October 1). Journal of Animal Science.

The effect of early weaning on feedlot performance and measures of stress in beef calves1,2

Arthington, J. D., Spears, J. W., & Miller, D. C. (2005, April 1). Journal of Animal Science.

Bioavailability of copper from tribasic copper chloride and copper sulfate in growing cattle

Spears, J. W., Kegley, E. B., & Mullis, L. A. (2004, July 15). Animal Feed Science and Technology.

Bioavailability of zinc from zinc sulfate and different organic zinc sources and their effects on ruminal volatile fatty acid proportions

Spears, J. W., Schlegel, P., Seal, M. C., & Lloyd, K. E. (2004, July 16). Livestock Production Science.

Effect of Zinc Source and Dietary Level on Zinc Metabolism in Holstein Calves

Wright, C. L., & Spears, J. W. (2004, April 1). Journal of Dairy Science.

Effect of dietary copper source (cupric citrate and cupric sulfate) and concentration on growth performance and fecal copper excretion in weanling pigs12

Armstrong, T. A., Cook, D. R., Ward, M. M., Williams, C. M., & Spears, J. W. (2004, April 1). Journal of Animal Science.

Effect of dietary trace mineral concentration and source (inorganic vs. chelated) on performance, mineral status, and fecal mineral excretion in pigs from weaning through finishing12

Creech, B. L., Spears, J. W., Flowers, W. L., Hill, G. M., Lloyd, K. E., Armstrong, T. A., & Engle, T. E. (2004, July 1). Journal of Animal Science, Vol. 82, pp. 2140–2147.

Effect of finishing system (feedlot or pasture), high-oil maize, and copper on conjugated linoleic acid and other fatty acids in muscle of finishing steers

Animal Science (Penicuik, Scotland), 78(2), 261–269.

Effects of Dietary Zinc on Performance and Immune Response of Growing Pigs Inoculated with Porcine Reproductive and Respiratory Syndrome Virus and Mycoplasma hyopneumoniae

Roberts, E. S., Heugten, E., Spears, J. W., Routh, P. A., Lloyd, K. L., & Almond, G. W. (2004, January 1). Asian-Australasian Journal of Animal Sciences, Vol. 17, pp. 1438–1446.

Growth performance, carcass characteristics, plasma minerals, and fecal mineral excretion in grower-finisher swine fed diets with levels of trace minerals lower than common industry levels

Journal of Swine Health and Production, 12(5), 237–241.

Advances in mineral nutrition for ruminants studied

Feedstuffs, 75(29), 12.

Effect of boron supplementation of pig diets on the production of tumor necrosis factor-α and interferon-γ1,2

Armstrong, T. A., & Spears, J. W. (2003, October 1). Journal of Animal Science.

Effect of copper source and level on performance and copper status of cattle consuming molasses-based supplements1,2

Arthington, J. D., Pate, F. M., & Spears, J. W. (2003, June 1). Journal of Animal Science.

Effects of High Dietary Calcium Propionate and Dietary Cation-Anion Balance on Calcium Metabolism and Longissimus Muscle Tenderness in Finishing Steers ,

Spears, J. W., Engle, T. E., Platter, W. R., Lloyd, K. E., Belk, K. E., & Horton, J. (2003, December 1). The Professional Animal Scientist.

Effects of breed (Angus vs Simmental) and copper and zinc source on mineral status of steers fed high dietary iron1,2

Mullis, L. A., Spears, J. W., & McCraw, R. L. (2003, January 1). Journal of Animal Science.

Effects of organic forms of zinc on growth performance, tissue zinc distribution, and immune response of weanling pigs1,2

Heugten, E., Spears, J. W., Kegley, E. B., Ward, J. D., & Qureshi, M. A. (2003, August 1). Journal of Animal Science, Vol. 81, pp. 2063–2071.