Richard A. Kohn
· ProfessorUniversity of Maryland, College Park · Animal and Avian Sciences
Active 1872–2023
About
Professor Richard A. Kohn is a faculty member in the Department of Animal & Avian Sciences at the University of Maryland. His research focuses on mathematical modeling for basic and applied research in animal nutrition, encompassing animal nutrient metabolism, whole-farm nutrient cycling, and life-cycle analysis. He works on developing next-generation fermentation systems for biofuel production, including methane, hydrogen, or liquid fuels derived from plant fiber through anaerobic digestion and fermentation processes. His environmental research investigates the impacts of animal production systems, particularly nutrient losses affecting water and air quality, and the influence of nutritional management on greenhouse gas emissions. He aims to improve the environmental footprint of animal agriculture by identifying and evaluating farm management strategies that reduce nutrient losses and enhance decision-making methods for farms. Additionally, he conducts research to improve nutrition and diet formulation for farm animals and delivers these findings through extension programs, educational advisement, and direct outreach to farmers. He also provides technical assistance to state and national programs focused on minimizing environmental damage from animal agriculture and supports the education of undergraduate and graduate students through advisement, committee participation, and lecturing.
Research topics
- Food science
- Biology
- Animal science
- Medicine
- Intensive care medicine
- Internal medicine
- Chemistry
- Bioinformatics
- Virology
- Chromatography
- Ecology
- Nursing
- Organic chemistry
- Biochemistry
- Emergency medicine
Selected publications
2023
- Medicine
- Emergency medicine
- Intensive care medicine
Journal of Dairy Science · 2022 · 28 citations
- Chemistry
- Chromatography
- Animal science
headspace emissions, primarily due to shifts in metabolic pathways of VFA formation, likely due to the observed changes in bacterial community structure. Significant interconversions occurred between acetate and butyrate, whereas interconversions of other VFA with propionate were relatively small. The InfAc and InfPr treatments increased net acetate and propionate production, respectively; however, interconversions among VFA were not affected by pH, acetate, or propionate treatments, suggesting that thermodynamics might not be a primary influencer of metabolic pathways used for VFA formation.
2022-05-01
articleSenior authorAnimals · 2022 · 30 citations
- Biology
- Animal science
- Food science
= 0.87), which could be developed as a valuable biomarker for optimizing milk fat yield and cattle growth. Therefore, our findings provided novel insights into microbial interactions in the rumen under different feed schemes and their ecophysiological implications. These findings will help to develop rumen manipulation strategies to improve feed conversion ratios and average daily weight gains for grass- or pasture-fed cattle production.
Patients’ Perspectives on Life and Recovery One Year After Severe COVID-19
2022-05-01
article2022-05-01
article2022-05-01
article2022-05-01
articlePSII-42 Kinetics of methanogenesis and acetogenesis under normal rumen conditions
Journal of Animal Science · 2019-12-01
articleOpen accessSenior authorAbstract Researchers are investigating numerous methods to reduce enteric methane emissions and improve the sustainability of US animal agriculture. Methane emissions from the rumen depend on principles of kinetics, where the profile of fermentation products depends on relative rates of competing reactions, substrate concentrations or enzymatic activities. We investigated the kinetics of methanogenesis and related VFA production under increasing concentrations of infused hydrogen. The H2 (0, 0.3, 0.5, 1, 2, 4, 6, 8, 10 mL) was added to Hungate tubes containing 10 mL of rumen fluid with 10 mL of CO2 headspace gas. Then H2, CH4 and CO2, and volatile fatty acid (VFA) concentrations were measured after 0 and 1 h incubation at 39 °C. Data were fit to a non-linear Michaelis-Menten (M-M) model to estimate Vmaxand Km. For initial rumen fluid without added H2gas, there was an increase in CH4, slight decrease in H2, and disappearance of acetate and propionate. When H2was added, H2disappearance increased linearly, and methane, acetate and propionate increased non-linearly. For example, methanogenesis Vmax was 0.209 mM 10mL-1minute-1 with Km of 67.2 mM (RMSPE = 0.09, n = 9). The ratio of appearance of CH4 to disappearance of H2 was 0.15, showing 60% of H2 disappearance was accounted for by methanogenesis. The H2 addition shifted fermentation from VFA degradation to synthesis via saturable pathways (e.g. at Vmax). Results show that rumen fluid has enzyme activity such that as H2 gas is made available to rumen fluid, most H2is used for methane and VFA synthesis, and rates and proportions of H2 utilization for different pathways can be measured in vitro.
Test of conditions that affect in vitro production of volatile fatty acids and gases1
Journal of Animal Science · 2018-01-29 · 14 citations
articleSenior authorCorrespondingIn vitro methods have been developed to measure digestibility, but such methods may not accurately reflect gas production or volatile fatty acid (VFA) profiles. The objective of this study was to determine the effect of different in vitro conditions on VFA and gas production. The experimental design was a 4 × 2 × 2 factorial CRD with four replicates. Treatments were four ratios of medium to rumen fluid by volume (5:95, 25:75, 50:50, and 75:25), two concentrations (w/v) of added timothy hay (0.5% or 1%), with or without added sodium acetate (increased initial concentration by 50 mM). Total volume of medium and rumen fluid was 10 mL per tube. Measurements of gas production and VFA were recorded at 0, 4, 16, 24, and 48 h. Statistical analyses used a mixed model including all fixed effects and interactions with tube as a random effect, and time nested within tube. Total gas production increased (P < 0.001) with higher medium proportion. The final pH increased (P < 0.0001) as medium proportion increased. Medium proportion positively affected (P < 0.05) overall average concentration of both acetate production and propionate production. Higher hay concentration increased (P < 0.0001) total gas produced from 0 to 48 h, increased total acetate production (P < 0.01), propionate production (P < 0.001), and decreased pH between 24 and 48 h (P < 0.0001). Sodium acetate addition increased (P < 0.0001) pH between 24 and 48 h. Acetate:propionate (A:P) concentration decreased over time (P < 0.0001). Initial rumen fluid A:P ratio was 3.7 but average A:P ratio of produced VFA started at 2.2 and increased to 2.50 (SE = ±0.51). The A:P ratio differed for VFA produced in vitro compared to initial rumen fluid, but no tested treatments were found to change A:P ratio.
Frequent coauthors
- 40 shared
James D. Ferguson
University of Pennsylvania
- 34 shared
Zhengxia Dou
University of Pennsylvania
- 30 shared
Z. Wu
- 29 shared
K.F. Knowlton
- 28 shared
John D. Toth
California University of Pennsylvania
- 27 shared
L.E. Chase
Cornell University
- 26 shared
C.F. Ramberg
- 26 shared
Lydie Chapuis‐Lardy
Université de Montpellier
Awards & honors
- Excellence in Extension Award
- Excellence in Instruction Award
- Excellence in Research Award
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