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Alexander N. Hristov, Ph.D., P.A.S.

  • Professor of Dairy Nutrition
Alexander N. Hristov, Ph.D., P.A.S.
352 Agricultural Sciences and Industries Building
University Park, PA 16802
Email:
Work Phone: 814-863-3669

Areas of Expertise

  • Dairy Nutrition
  • Protein Nutrition of Dairy Cows
  • Rumen Fermentation
  • Nitrogen Utilization
  • Methane Mitigation
  • Environment

Education

  1. Ph.D., Academy of Agricultural Sciences, Sofia, Bulgaria, 1993
  2. B.Sc., Higher Institute of Zooengineering and Veterinary Medicine, Stara Zagora, Bulgaria, 1983

Professional Experience

  • 2013-Present:  Professor of Dairy Nutrition, Department of Animal Science, Penn State
  • 2008-2013: Associate Professor of Dairy Nutrition, Department of Animal Science, Penn State
  • 1999-2008: Associate Professor, Department of Animal and Veterinary Science, University of Idaho
  • 1997-1999: Term Research Scientist II, Agriculture Canada, Lethbridge Research Centre, Canada
  • 1995-1997: Visiting Scientist, Agriculture Canada, Lethbridge Research Centre, Canada
  • 1990-1991, 1993: Visiting Scientist, US Dairy Forage Research Center, Madison, Wisconsin
  • 1983-1997: Research Scientist, Institute of Animal Sciences, Kostinbrod, Bulgaria

SOCIETY AFFILIATIONS AND SERVICE:

  • American Dairy Science Association, American Society of Animal Science, Federation of Animal Science Societies, American Registry of Professional Animal Scientists.
  • Chair, Network and Database on Feed and Nutrition in Relation to Greenhouse gas Emissions (FNN), an activity of the Livestock Research Group within the Global Research Alliance.
  • Feed Composition Committee of the National Animal Nutrition Program (NANP).
  • Regional Project NC-1040 Committee representative: Metabolic Relationships in Supply of Nutrients for Lactating Cows.
  • Editorial Board member, Journal of Dairy Science; Associate Editor, Journal of Agricultural Sciences (Cambridge); Past Associate and Division Editor, Ruminant Nutrition, Journal of Animal Science. Past Associate Editor, Canadian Journal of Animal Science.

 TEACHING RESPONSIBILITIES:

                ANSC420 Animal Nutrition and Feed Technology

                ANSC506 Ruminology

                ANSC410 Advanced Dairy Management, dairy nutrition section

Lead Instructor: Dairy Production and Management MOOC (Massive Open Online Course; https://www.coursera.org/learn/dairy-production)

Refereed publications, books, and book chapters: over 150 (over 60 in the last 5 yrs.); Invited talks in the last 5 yrs: over 35

 SCHOLARSHIP ACCOMPLISHMENTS:

Google Scholar stats (updated January 2018)

Citation indices

All

Since 2013

Citations

6,856

4,159

h-index

47

36

i10-index

101

90

 

 

Selected Publications:


Books:  

  • A. Leip, E. Ledgard, A. Uwizeye, M. F. Aller, B. Amon, G. Becoña, M. Binder, J. Buysse, C. de Camillis, N. M. D. Cosme, A. Fusi, C. Gourley, J. Helin, A. Henderson, D. Hongmin, S. Hörtenhuber, A. N. Hristov, R. Koelsch, K. Linderholm, C. Liu, C. L. Piquet, C. Masso, C. Cordovil, M. Meier, N. Nsalambi, C. Opio, A. K. Patra, G. Peyroutou, M. Redding, M. Rufino, R. Sakrabani, G. Thoma, D. Turner, F. Vertès, Y. Wang, D. W. Raffa, and Z. Zhu. 2017. Guidelines for environmental quanti­fication of nutrient flows and impact assessment in livestock supply chains. FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS and LIVESTOCK ENVIRONMENTAL ASSESSMENT AND PERFORMANCE PARTNERSHIP, Rome, 2017.
  • Hristov, A. N., J. Oh, C. Lee1, R. Meinen, F. Montes, T. Ott, J. Firkins, A. Rotz, C. Dell, A. Adesogan, W. Yang, J. Tricarico, E. Kebreab, G. Waghorn, J. Dijkstra, and S. Oosting. 2013. Mitigation of greenhouse gas emissions in livestock production – A review of technical options for non-CO2 emissions. Edited by Pierre J. Gerber, Benjamin Henderson and Harinder P.S. Makkar. FAO Animal Production and Health Paper No. 177, FAO, Rome, Italy.
  • Pfeffer, E., and A. N. Hristov (Editors). 2005. Nitrogen and Phosphorus Nutrition of Cattle: Reducing the Environmental Impact of Cattle Operations. CABI Publishing, Wallingford, U.K. (ISBN 0 85199 013 4).

 Book Chapters:

  • A. N. Hristov, J. M. F. Johnson, C. W. Rice, M. E. Brown, R. T. Conant, S. J. Del Grosso, N. P. Gurwick, C. A. Rotz, U. M. Sainju, R. H. Skinner, T. O. West, B. R. K. Runkle, H. Janzen, S. Reed, N. Cavallaro, and G. Shestha. 2017. Chapter 5. Agriculture in Second State of the Carbon Cycle Report 3 (SOCCR-2), U.S. GLOBAL CHANGE RESEARCH PROGRAM.
  • Hristov, A. N. 2017. Agricultural Methanogenesis. Oxford Encyclopedia of Agriculture and the Environment. http://environmentalscience.oxfordre.com/view/10.1093/acrefore/9780199389414.001.0001/acrefore-9780199389414-e-190?rskey=O5r0SJ&result=4.
  • Oh, J. and A. N. Hristov. 2016. Effects of plant-derived bio-active compounds on rumen fermentation, nutrient utilization, immune response, and productivity of ruminant animals. In Medicinal and Aromatic Crops: Production, Phytochemistry, and Utilization, Chapter 11, pp 167–186, DOI: 10.1021/bk-2016-1218.ch011, ACS Symposium Series, Vol. 1218.
  • Patton, R. A., A. N. Hristov, and H. Lapierre, 2014. Protein Feeding and Balancing for Amino Acid in Lactating Dairy Cattle. Pp 599-621 in: Veterinary Clinics of North America. Eds. R. J. Van Saun and R. A. Smith. Elsevier, Philadelphia, USA.
  • Ndegwa, P. M., A. N. Hristov, and J. A. Ogejo.  2011. Ammonia Emission from Animal Manure: Mechanisms and Mitigation Techniques. Pages 107-151 In Z. He, ed. Environmental Chemistry of Animal Manure.  Nova Science Publishers, Hauppauge, NY. ISBN: 978-1-61209-222-5.
  • Hristov, A. N., and Jouany, J.-P. 2005. Factors affecting the efficiency of nitrogen utilization in the rumen. In: Pfeffer, E., and A. N. Hristov (eds.) Nitrogen and Phosphorus Nutrition of Cattle: Reducing the Environmental Impact of Cattle Operations. CAB International, Wallingford, U.K., pp. 117-166.

       

Journals:

Journal of Dairy Science’s 100 most cited papers published since the beginning of 2014: Lee, C., F. Giallongo, A. N. Hristov, H. Lapierre, T. W. Cassidy, K. S. Heyler, G. A. Varga, and C. Parys. 2015. Effect of dietary protein level and rumen protected amino acid supplementation on amino acid utilization for milk protein in lactating dairy cows. J. Dairy Sci. 98:1885–1902.

Journal of Dairy Science’s 2011 most-cited article: Hristov, A. N., C. Lee, T. Cassidy, M. Long, K. Heyler, B. Corl, and R. Forster. 2011. Effects of lauric and myristic acids on ruminal fermentation, production, and milk fatty acid composition in lactating dairy cows. J. Dairy Sci. 94:382–395.

Ranked among the 100 most highly cited papers published in J. Dairy Sci. since the beginning of 2012. Lee, C., A. N. Hristov, T. W. Cassidy, K. S. Heyler, H. Lapierre, G. A. Varga, M. J. de Veth, R. A. Patton, and C. Parys. 2012. Rumen-protected lysine, methionine, and histidine increase milk protein yield in dairy cows fed metabolizable protein-deficient diet. J. Dairy Sci. 95:6042–6060.

Atmosphere’s fifth most-cited article: Lee, C., A. N. Hristov, T. Cassidy and K. Heyler. 2011. Nitrogen isotope fractionation and origin of ammonia nitrogen volatilized from cattle manure in simulated storage. Atmosphere 2:256-270; doi:10.3390/atmos2030256.

No. 1 most cited biosystems engineering articles published since 2008. Ndegwa, P.M., A. N. Hristov, J. Arogo, and R. E. Sheffield. 2008. A Review of Ammonia Emissions Mitigation Techniques for Concentrated Animal Feeding Operations. Biosystems Engineering 100:453 – 469.

  • A. N. Hristov, E. Kebreab, M. Niu, J. Oh, C. Arndt, A. Bannink, A. R. Bayat, A. F. Brito, D. Casper, L. A. Crompton, J. Dijkstra, P. C. Garnsworthy, N. Haque, A. L. F. Hellwing, P. Huhtanen, M. Kreuzer, B. Kuhla, P. Lund, J. Madsen, S. C. McClelland, P. Moate, C. Muñoz, N. Peiren, J. M. Powell, C. K. Reynolds, A. Schwarm, K. J. Shingfield, T. M. Storlien, M. R. Weisbjerg, Z. Yu, T.B. Boland, C. Martin, M. Eugène, D. R. Yáñez-Ruiz, S. Muetzel. 2018. Symposium review: Uncertainties in enteric methane inventories, measurement techniques, and prediction models. J. Dairy Sci. doi.org/10.3168/jds.2017-13536.
  • Oh, J., M. Harper, C. H. Lang, E. H. Wall, and A. N. Hristov. 2018. Effects of phytonutrients alone or in combination with monensin on productivity in lactating dairy cows. J. Dairy Sci. doi: 10.3168/jds.2018-14439.
  • Niu, M., E. Kebreab, A. N. Hristov, J. Oh, C. Arndt, A. Bannink, A. R. Bayat, A. F. Brito, T. Boland, D. Casper, L. A. Crompton, J. Dijkstra, M. A. Eugène, P. C. Garnsworthy, M. N. Haque, A. L. F. Hellwing, P. Huhtanen, M. Kreuzer, B. Kuhla, P. Lund, J. Madsen, C. Martin, S. C. McClelland, M. McGee, P. J. Moate, S. Muetzel, C. Muñoz, P. O’Kiely, N. Peiren, C. K. Reynolds, A. Schwarm, K. J. Shingfield, T. M. Storlien, M. R. Weisbjerg, D. R. Yáñez-Ruiz, and Z. Yu. 2018. Prediction of enteric methane production, yield and intensity in dairy cattle using an intercontinental database. Global Change Biology. doi: 10.1111/gcb.14094.
  • Harper, M. T., A. Melgar, J. Oh, K. Nedelkov, G. Sanchez, G. W. Roth, and A. N. Hristov. 2018. Inclusion of brown midrib dwarf pearl millet silage in the diet of lactating dairy cows. J. Dairy Sci. doi: 10.3168/jds.2017-14036.
  • A. N. Hristov, M. Harper, R. Meinen, R. Day, J. Lopes, T. Ott, A. Venkatesh, and C. A. Randles. 2017. Discrepancies and uncertainties in bottom-up gridded inventories of livestock methane emissions for the contiguous United States. Environ. Sci. Technol. doi: 10.1021/acs.est.7b03332.
  • A. N. Hristov, M. Harper, J. Oh, F. Giallongo, J. C. Lopes, G. Cudoc,  J. Clay, R. Ward, and L. E. Chase. 2017. Short communication: Variability in milk urea nitrogen and dairy total mixed ration composition in the Northeast United States. J. Dairy Sci. doi: 10.3168/jds.2017-12925.
  • A. N. Hristov, A. T. Degaetano, C. A. Rotz, E. Hoberg, H. Skinner, T. Felix, H. Li, P. Patterson, G. Roth,  M. Hall, T. L. Ott, L. Baumgard, W. Staniar, M. Hulet, C. Dell, A. Brito, D. Hollinger. 2017. Climate change effects on livestock in the northeast US and strategies for adaptation. Climatic Change, available online @ doi:10.1007/s10584-017-2023-z.
  • Harper, M., J. Oh, F. Giallongo, J. C. Lopes, G. W. Roth, and A. N. Hristov. 2017. Using brown midrib dwarf forage sorghum silage and fall grown oat silage in lactating dairy cow rations. J. Dairy Sci. 100:5250–5265.
  • Harper, M., J. Oh, F. Giallongo, G. W. Roth, and A. N. Hristov. 2017. Effects of feeding triticale and wheat silages on feed intake, milk production and composition, and enteric methane production in lactating dairy cows. J. Dairy Sci. 100:6151–6163.
  • J. Oh, E. H. Wall, D. M. Bravo, and A. N. Hristov. 2017. INVITED REVIEW: Host-mediated effects of phytonutrients in ruminants. J. Dairy Sci. 100:5974–5983.
  • Oh, J., M. Harper, F. Giallongo, D. Bravo, E. H. Wall, and A. N. Hristov. 2017. Effects of rumen-protected Capsicum oleoresin on productivity and responses to a glucose tolerance test in lactating dairy cows. J. Dairy Sci. 100:1888–1901.
  • Oh, J., M. Harper, F. Giallongo, D. Bravo, E. H. Wall, and A. N. Hristov. 2017. Effects of rumen-protected Capsicum oleoresin on immune responses in dairy cows intravenously challenged with lipopolysaccharide. J. Dairy Sci. 100:1902–1913.
  • Lopes, J. C., M. T. Harper, F. Giallongo, J. Oh, L. Smith, A. M. Ortega-Perez, S. A. Harper, A. Melgar, D. M. Kniffen, R. A. Fabin, and A. N. Hristov. 2017. Effect of high-oleic acid soybeans on production performance, milk fatty acid composition, and enteric methane emission in dairy cows. J. Dairy Sci. 100:1122–1135.
  • Giallongo, F., M. T. Harper, J. Oh, C. Parys, I. Shinzato, and A. N. Hristov. 2017. Effects of a histidine-deficient diet on lactational performance of dairy cows. J. Dairy Sci. 100:2784–2800.
  • Weeks, H. L., and A. N. Hristov. 2017. Short communication: Discrepancies in milk urea nitrogen concentration analysis among milk processing laboratories in Pennsylvania. J. Dairy Sci. 100:1502–1506.
  • Hammond, K. J., L. A. Crompton, A. Bannink, J. Dijkstra, D. R. Yáñez-Ruiz, P. O’Kiely, E. Kebreab, M. A. Eugenè, Z. Yu, K. J. Shingfield, A. Schwarm, A. N. Hristov, C. K. Reynolds. 2016. Review of current in vivo measurement techniques for quantifying enteric methane emission from ruminants. Anim. Feed Sci. Technol. 219:13-30.
  • Lopes, J. C., L. F. de Matos, M. T. Harper, F. Giallongo, J. Oh, D. Gruen, S. Ono, M. Kindermann, S. Durval, and A. N. Hristov. 2016. Effect of 3-nitrooxipropanol on ruminal fermentation, methane and hydrogen emissions, and methane isotopic signature in dairy cows. J. Dairy Sci. 99:5335-5344. doi: 10.3168/jds.2015-10832.
  • Harper, M. T., J. Oh, F. Giallongo, J. C. Lopes, H. L. Weeks, J. Faugeron, and A. N. Hristov. 2016. Short communication: Preference of flavored concentrate premixes by dairy cows. J. Dairy Sci. 99:6585-6589.
  • Giallongo, F., M. Harper, J. Oh, J. Lopes, H. Lapierre, R. A. Patton, I. Shinzato, C. Parys, and A. N. Hristov. 2016. Effects of rumen-protected methionine, lysine and histidine on lactation performance of dairy cows. J. Dairy Sci. 99:4437-4452.
  • Hristov, A. N., J. Oh, F. Giallongo, T. Frederick, M. T. Harper, H. Weeks, A. F. Branco, W. J. Price, P. J. Moate, M. H. Deighton, S. R. O. Williams, M. Kindermann, and S. Duval. 2016. Short communication: Comparison between the GreenFeed system and the sulfur hexafluoride tracer technique for measuring enteric methane emissions from dairy cows. J. Dairy Sci. 99:5461–5465.
  • Sadri, H., F. Giallongo, A. N. Hristov, J. Werner, C. Lang, C. Parys, B. Saremi, and H. Sauerwein. 2016. Effects of slow-release urea and rumen-protected methionine and histidine on mTOR signaling and ubiquitin proteasome-related gene expression in skeletal muscle of dairy cows fed a metabolizable protein-deficient diet. J. Dairy Sci. 99:6702-6713. 
  • Herrero, M., B. Henderson, P. Havlík, P. K. Thornton, R. T. Conant, P. Smith, S. Wirsenius, A. N. Hristov, P. Gerber, M. Gill, K. Butterbach-Bahl, H. Valin, T. Garnett, and E. Stehfest. 2016. Greenhouse gas mitigation potentials in the livestock sector. Nature Climate Change 6:452–461. doi:10.1038/nclimate2925.
  • Yáñez-Ruiz D. R., A. Bannink, J. Dijkstra, E. Kebreab, D. Morgavi, P. O´Kiely, C. K. Reynolds, A. Schwarm, K. Shingfield, Z. T. Yu, and A. N. Hristov. 2016. Design, implementation and interpretation of in vitro batch culture experiments to assess methane mitigation in ruminants – a review. Anim. Feed Sci. Technol. 216:1-18.
  • Church, C. D., A. N. Hristov, R. B. Bryant, P. J. A. Kleinman, and S. K. Fishel. 2016. A novel treatment system to remove phosphorus from liquid manure. Appl. Eng. Agric. 32:103-112. DOI 10.13031/aea.32.10999.
  • Hristov, A. N., J. Oh, F. Giallongo, T. Frederick, M. Harper,  H. Weeks, A. Branco, P. Moate, M. Deighton, R. Williams, M. Kindermann, and S. Duval. 2015. An inhibitor persistently decreased enteric methane emission from dairy cows with no negative effect on milk production. Proc. Nat. Acad. Sci. U.S.A. 112:10663–10668. doi: 10.1073/pnas.1504124112.
  • Patton R. A., A. N. Hristov, C. Parys, and H. Lapierre. 2015. Relationships between circulating plasma concentrations and duodenal flows of essential amino acids in lactating dairy cows. J. Dairy Sci.98:4707-4734.
  • Weeks, H. L., T. W. Frederick, L. M. Hagan, K. Heyler, J. Oh, A. N. Hristov. 2015. Case Study: Farm-level evaluation of implementing nitrogen and phosphorus feeding best management practices on Pennsylvania dairy farms. Prof. Anim. Sci. 31:473-483.
  • Oh, J., A. N. Hristov, F. Giallongo, T. Frederick, J. Pate, S. Walusimbi, R. Elias, and E. H. Wall. 2015. Effects of dietary Capsicum extract supplementation on productivity and immune responses in lactating dairy cows. J. Dairy Sci. 98:6327–6339.
  • Giallongo, F., T. Frederick, J. Oh, B. Isenberg, D. M. Kniffen, A. N. Hristov, and R. A. Fabin. 2015. Extruded soybean meal increased feed intake and milk production in dairy cows. J. Dairy Sci. 98:6471–6485.
  • Wang, D. T., D. S. Gruen, B. S. Lollar, K-U. Hinrichs, L. C. Stewart, J. F. Holden, A. N. Hristov, J. W. Pohlman, P. L. Morrill, M. Könneke, K. B. Delwiche, E. P. Reeves, C. N. Sutcliffe, D. J. Ritter, J. S. Seewald, J. C. McIntosh, H. F. Hemond, M. D. Kudo, D. Cardace, T. M. Hoehler, and S. Ono. 2015. Unique non-equilibrium clumped isotope signals in microbial methane. Science. 348:428-431. DOI: 10.1126/science.aaa4326.
  • Hristov, A. N., J. Oh, F. Giallongo, T. Frederick, H. Weeks, P. R. Zimmerman, R. A. Hristova, S. R. Zimmerman, and A. F. Branco. 2015. The use of an automated system (GreenFeed) to monitor enteric methane and carbon dioxide emissions from ruminant animals. J. Visualized Experiments 103:e52904; doi:10.3791/52904.
  • Branco, A. F., F. Giallongo, T. Frederick, H. Weeks, J. Oh, and A. N. Hristov. 2015. Effect of technical cashew nut shell liquid on rumen methane production and lactation performance of dairy cows. J. Dairy Sci. 98:4030–4040.
  • Giallongo, F., A. N. Hristov, J. Oh, T. Frederick, H. Weeks, J. Werner, H. Lapierre, R. A. Patton, A. Gehman, and C. Parys. 2015. Effects of slow-release urea and rumen-protected methionine and histidine on performance of dairy cows fed a metabolizable protein-deficient diet. J. Dairy Sci. 98:3292–3308.
  • Lee, C., J. Oh, A. N. Hristov, K. Harvatine, M. Vazquez-Anon, and G. I. Zanton. 2015. Effect of 2-hydroxy-4-methylthio-butanoic acid on ruminal fermentation, digestibility, and performance of lactating dairy cows. J. Dairy Sci. 98:1234–1247.
  • Lee, C., F. Giallongo, A. N. Hristov, H. Lapierre, T. W. Cassidy, K. S. Heyler, G. A. Varga, and C. Parys. 2015. Effect of dietary protein level and rumen protected amino acid supplementation on amino acid utilization for milk protein in lactating dairy cows. J. Dairy Sci. 98:1885–1902.
  • Hristov, A. N., K. Heyler, E. Schurman, K. Griswold, P. Topper, M. Hile, V. Ishler, E. Wheeler, and S. Dinh. 2015. Reducing dietary protein decreased the ammonia emitting potential of manure from commercial dairy farms. Prof. Anim. Sci. 31:68-79.
  • Meale, S. J., K. A. Beauchemin, A. N. Hristov, A. V. Chaves, and T. A. McAllister. 2014. BOARD-INVITED REVIEW: Opportunities and challenges in using exogenous enzymes to improve ruminant production. J. Anim. Sci. 92:427-442.
  • Lee, C., G. W. Feyereisen, A. N. Hristov, C. J. Dell, J. Kaye, and D. Beegle. 2014. Effects of dietary protein concentration on ammonia volatilization, nitrate leaching, and plant nitrogen uptake from dairy manure applied to lysimeters. J. Environ. Qual. 43:398–408.
  • Hristov, A. N., K. A. Johnson, E. Kebreab. 2014. Livestock methane emissions in the United States. Proc. Natl. Acad. Sci. USA, 10.1073/pnas.1401046111.
  • Faciola, A. P., G. A. Broderick, A. N. Hristov, and M. I. Leã. 2013. Effects of lauric acid on ruminal protozoal numbers and fermentation pattern and milk production in lactating dairy cows. J. Anim. Sci. 91:2243-2253.
  • Lee, C., and A. N. Hristov. 2014. Short communication: Comparison of 3 solid digesta passage markers in dairy cows. J. Dairy Sci. 97:1725–1729.
  • Oh, J., A. N. Hristov, C. Lee, T. Cassidy, K. Heyler, G. A. Varga, J. Pate, S. Walusimbi, E. Brzezicka, K. Toyokawa, J. Werner, S. S. Donkin, R. Elias, S. Dowd, and D. Bravo. 2013. Immune and production responses of dairy cows to postruminal supplementation with phytonutrients. J. Dairy Sci. 96:7830–7843.
  • Hristov, A. N., J. Oh, J. Firkins, J. Dijkstra, E. Kebreab, G. Waghorn, H. P. S. Makkar, A. T. Adesogan, W. Yang, C. Lee, P. J. Gerber, B. Henderson, and J. M. Tricarico. 2013. Mitigation of methane and nitrous oxide emissions from animal operations: I. A review of enteric methane mitigation options. J. Anim. Sci. 91:5045–5069.
  • Montes, F., R. Meinen, C. Dell, A. Rotz, A. N. Hristov, J. Oh, G. Waghorn, P. J. Gerber, B. Henderson, and H. P. S. Makkar, and J. Dijkstra. 2013. Mitigation of methane and nitrous oxide emissions from animal operations: II. A review of manure management mitigation options. J. Anim. Sci. 91:5070–5094. 
  • Hristov, A. N., T. Ott, J. Tricarico, A. Rotz, G. Waghorn, A. Adesogan, J. Dijkstra, F. Montes, J. Oh, E. Kebreab, S. J. Oosting, P. J. Gerber,  B. Henderson, H. P. S. Makkar, and J. Firkins. 2013. Mitigation of methane and nitrous oxide emissions from animal operations: III. A review of animal management mitigation options. J. Anim. Sci. 91:5095–5113.
  • Tekippe, J. A., R. Tacoma, A. N. Hristov, C. Lee, J. Oh, K. S. Heyler, T. W. Cassidy, G. A. Varga, and D. Bravo. 2013. Effect of plant phytochemicals on ruminal fermentation and lactation performance of dairy cows. J. Dairy Sci. 96:7892–7903.
  • Hristov, A. N. 2013. Diet formulation as an effective tool for mitigating nitrogen excretion in dairy systems. Adv. Anim. Biosci. 4:s1:15–18.
  • Gerber, P. J., A. N. Hristov, B. Henderson, H. Makkar, J. Oh, C. Lee, R. Meinen, F. Montes, T. Ott, J. Firkins, Al Rotz, C. Dell, A. Adesogan, W. Z. Yang, J.Tricarico, E. Kebreab, G. Waghorn, J. Dijkstra, and S. Oosting. 2013. Technical options for the mitigation of direct methane and nitrous oxide emissions from livestock – a review. Animal 7(s2):220–234.
  • Lee, C., and A. N. Hristov. 2013. Short communication: Evaluation of acid-insoluble ash and indigestible neutral-detergent fiber as total tract digestibility markers in dairy cows fed a corn silage-based diet. J. Dairy Sci. 96:5295–5299.
  • Hristov, A. N., C. Lee, T. Cassidy, K. Heyler, J. A. Tekippe, G. A. Varga, B. Corl, and R. C. Brandt. 2013. Effect of Origanum vulgare L. leaves on rumen fermentation, production, and milk fatty acid composition in lactating dairy cows. J. Dairy Sci. 96: 1189-1202.
  • Tekippe, J. A., A. N. Hristov, K. S. Heyler, V. D. Zheljazkov, J. F. S. Ferreira, C. L. Cantrell, and G. A. Varga. 2012. Effects of plants and essential oils on ruminal in vitro batch culture methane production and fermentation. Can. J. Anim. Sci. 92:395-408.
  • Lee, C., A. N. Hristov, T. W. Cassidy, K. S. Heyler, H. Lapierre, G. A. Varga, M. J. de Veth, R. A. Patton, and C. Parys. 2012. Rumen-protected lysine, methionine, and histidine increase milk protein yield in dairy cows fed metabolizable protein-deficient diet. J. Dairy Sci. 95:6042–6060. 
  • Hristov, A. N., C. Lee, R. A. Hristova, P. Huhtanen, and J. Firkins. 2012. A meta-analysis of the variability in continuous culture rumen fermentation and digestibility data. J. Dairy Sci. 95:5299–5307.
  • Hristov, A. N., T. R. Callaway, C. Lee, and S. E. Dowd. 2012. Ruminal bacterial, archaeal, and fungal diversity of dairy cows with normal and reduced ruminal fauna. J. Anim. Sci. 90:4449-4457.
  • Lee, C., A. N. Hristov, K. S. Heyler, T. W. Cassidy, H. Lapierre, G. A. Varga, and C. Parys. 2012. Effects of metabolizable protein supply and amino acids supplementation on nitrogen utilization, production and ammonia emissions from manure in dairy cows. J. Dairy Sci. 95:5253–5268.
  • Lee, C., A. N. Hristov, C. J. Dell, G. W. Feyereisen, J. Kaye, and D. Beegle. 2012. Effect of dietary protein concentration on ammonia and greenhouse gas emissions from dairy manure. J. Dairy Sci. 95:1930–1941.
  • Hristov, A. N. 2012. Historic, pre-European settlement, and present-day contribution of wild ruminants to enteric methane emissions in the United States. J. Anim. Sci. 90:1371-1375.
  • Lee, C., A. N. Hristov, T. Cassidy and K. Heyler. 2011. Nitrogen isotope fractionation and origin of ammonia nitrogen volatilized from cattle manure in simulated storage. Atmosphere 2:256-270; doi:10.3390/atmos2030256. (Atmosphere’s fifth most-cited article)
  • Lee, C., A. N. Hristov, K. S. Hyler, T. W. Cassidy, M. Long, B. A. Corl, and S. K. R. Karnati. 2011. Effects of dietary protein concentration and coconut oil supplementation on nitrogen utilization and production in dairy cows. J. Dairy Sci. 94:5544–5557.
  • Hristov, A. N. 2011. Contribution of ammonia emitted from livestock to atmospheric PM2.5 in the United States. J. Dairy Sci. 94:3130-3136.
  • Hristov, A. N., M. Hanigan, A. Cole, R. Todd, T. A. McAllister, P. M. Ndegwa, and A. Rotz. 2011. Ammonia emissions from dairy farms and beef feedlots: A review. Can. J. Anim. Sci. 91:1-35.
  • Hristov, A. N., C. Lee, T. Cassidy, M. Long, K. Heyler, B. Corl, and R. Forster. 2011. Effects of lauric and myristic acids on ruminal fermentation, production, and milk fatty acid composition in lactating dairy cows. J. Dairy Sci. 94:382–395.
  • Hristov, A. N., D. Mertens, S. Zaman, M. Vander Pol, and W. J. Price. 2010. Variability in feed and total mixed ration neutral-detergent fiber and crude protein analyses among commercial laboratories. J. Dairy Sci. 93:5348–5362.
  • Agle, M., A. N. Hristov, S. Zaman, C. Schneider, P. Ndegwa, and V. K. Vaddella. 2010. Effects of ruminally degraded protein on rumen fermentation and ammonia losses from manure in dairy cows. J. Dairy Sci. 93:1625–1637.
  • Hristov, A. N.,  G. Varga, T. Cassidy, M. Long, K. Heyler, K. R. Karnati, B. Corl, C. J. Hovde,  and I. Yoon. 2010. Effect of yeast culture on ruminal fermentation and nutrient utilization in dairy cows. J. Dairy Sci. 93:682–692. 
  • Hristov, A. N., M. Vander Pol, M. Agle, S. Zaman, C. Schneider, P. Ndegwa, V. K. Vaddella, K. Johnson, K. J. Shingfield, and S. K. R. Karnati. 2009. Effect of lauric acid and coconut oil on ruminal fermentation, digestion, ammonia losses from manure, and milk fatty acid composition in lactating cows. J. Dairy Sci. 92:5561–5582.
  • Hristov, A. N., S. Zaman, M. Vander Pol, L. Campbell, P. Ndegwa, and S. Silva. 2009. Nitrogen losses from dairy manure estimated through nitrogen mass balance or using markers. J. Environ. Qual. 38:2438–2448.
  • Huhtanen, P., and A. N. Hristov. 2009. A meta-analysis of the effects of protein concentration and degradability on milk protein yield and milk N efficiency in dairy cows. J. Dairy Sci. 92:3222–3232.