About

Lee Johnston is a Professor in the Department of Animal Science at the University of Minnesota Twin Cities. He holds a Ph.D. from Michigan State University (1988), an M.S. from Texas Tech University (1984), and a B.S. from Penn State University (1982). His research focuses on swine nutrition and management, including energy and protein nutrition of sows, feedstuff evaluation, management of reproducing sows, nutrition/environment interactions, nutrition of the newly weaned pigs, and the use of renewable energy in pork production systems. Johnston has contributed to numerous publications in the field, advancing understanding of dietary impacts on pig performance, gut microbiota, and environmental sustainability in animal production systems.

Research topics

• Microbiology
• Biology
• Internal medicine
• Immunology
• Medicine
• Biochemistry

Selected publications

• Carbohydrates: How structural features influence digestion-fermentation kinetic parameters

  Food Chemistry · 2026-03-12 · 2 citations

  article
  PublisherDOI

• Potential Role of Hybrid Rye in Crop Rotations for Provision of Feed and Bedding in Organic Pig Production: A Simulation Study

  Sustainability · 2026-03-10

  articleOpen access

  This study utilized a modeling approach to explore the long-term effects of integrating hybrid rye into organic crop production on crop yields and water use, and rye’s theoretical impact on feed and bedding self-sufficiency in organic pig production. Crop yield and water use were simulated using DSSAT models for three exploratory scenarios (R1: corn–soybean–silage followed by 3 years of alfalfa; R2: rye replaced the first year of alfalfa; and R3: rye replaced the third year of alfalfa). Potential feed and bedding requirements were estimated based on a recently completed pig feeding trial. The models predicted higher rye yields and water use in R3 than in R2 (p < 0.01), suggesting a theoretical yield benefit when rye follows alfalfa. Based on these simulations, R3 could potentially provide feed and bedding for a 38 pigs·ha−1·rotation cycle−1, compared to a 10 pigs·ha−1·rotation cycle−1 in R2. While these findings represent theoretical scenarios rather than validated field performance, they demonstrate the potential of crop simulations for evaluations of long-term effects of organic crop rotations on yield and water use. The results suggest that integrating hybrid rye after legumes warrants further field-scale validation as a strategy to enhance resource self-sufficiency in organic pig production.

  PublisherOA PDFDOI

• Simulation and validation of hydraulic track drive systems for electrification of heavy-duty machinery

  Scientific Reports · 2025-08-26 · 1 citations

  articleOpen access

  This work explores the challenges and necessity of replacing inefficient hydraulic systems in large-scale heavy-duty off-road machinery, such as mobile rock crushers, with innovative electric solutions. A mathematical and Simulink simulation model of a rock crusher's hydraulic track drive is developed and validated against physical test data. The model investigates the power developed by the hydraulic system during operation via simulation and is validated using results obtained from physical testing of the machine. These findings can inform the specification of an equivalent electric system, enabling similar torque delivery without the idle energy losses typical of fossil fuel systems. The simulation also supports appropriate energy storage sizing to perform required manoeuvres. The simulated system accuracy ranges from 4 to 12%, with a 20% outlier attributed to real-world inefficiencies like fluid losses and transient response delays. This level of accuracy is considered sufficient for guiding electrification efforts, ensuring the proposed electric system is neither under- nor over-designed. The insights gained from this simulation work contribute to the transition of heavy-duty machinery from hydraulic to electric powertrains, supporting the development of more energy-efficient and sustainable solutions.

  PublisherOA PDFDOI

• Determination and prediction of net energy of soybean meal fed to pregnant sows by indirect calorimetry

  Animal Bioscience · 2025-02-27 · 2 citations

  articleOpen access

  OBJECTIVE: The study was conducted to investigate the appropriate substitution level of soybean meal (SBM) for determining its net energy (NE), and establish NE prediction equation of SBM based on the determined NE values for pregnant sows. METHODS: In Exp. 1, eighteen pregnant sows (Landrace×Yorkshire; parity, 2 to 3) with an initial body weight (BW) of 221.2±2.6 kg at mid-gestation were blocked by BW and randomly assigned into 3 groups. Three groups fed with a corn-SBM basal diet and two test diets with 15% and 30% energy-supplying components replaced by SBM, respectively. In Exp. 2, six diets were formulated including a corn-SBM basal diet and five SBM diets (based on the substitution level determined of Exp. 1) with different soybean sources and processing methods. Moreover, 12 pregnant pigs (BW = 209.0±3.0 kg; parity, 3 to 4) at mid-gestation were arranged in a 6×3 Youden square design. RESULTS: Increasing substitution levels of SBM linearly increased (p<0.05) fecal and urinary nitrogen excretion and the ratio of urinary energy to digestible energy (DE), while linearly decreased (p<0.05) the ratio of metabolizable energy (ME) to DE and tended to linearly decrease dietary ME (p = 0.066) and NE (p = 0.074). The coefficient of variation for the NE of SBM was lower at a 15% substitution level compared to a 30% substitution level. The nutritional compositions of SBM are influenced by the soybean sources and processing methods. As dry matter basis, NE values of SBM ranged from 11.1 to 12.7 MJ/kg and the best-fitted prediction equation for NE of SBM was: NE (MJ/kg) = -91.71+5.35×gross energy (%)-0.03×neutral detergent fiber (%; R2 = 0.96). CONCLUSION: A substitution level of 15% was more appropriate to determine NE of SBM. Furthermore, NE values of SBM can be predicted based on their chemical compositions.

  PublisherOA PDFDOI

• Dietary winter hybrid rye minimally influences performance and carcass characteristics of organically-raised growing-finishing pigs

  Frontiers in Sustainable Food Systems · 2025-05-01 · 3 citations

  articleOpen access

  This study evaluated the utility of winter hybrid rye as a partial replacement for corn in an organic pig production system. Winter hybrid rye replaced 50% of corn in diets for growing-finishing pigs raised organically to determine pig performance, carcass characteristics, and phosphorus concentrations in fecal samples. A total of 500 pigs (initial body weight = 18.9 ± 2.94 kg) were assigned to either a Control or Rye treatment (50 pigs/pen; 5 pens/treatment) balanced for sex and body weight. Control pigs received a corn-soybean meal diet, while Rye pigs were fed a diet where hybrid rye replaced 50% of the corn in the control diet. Pigs were housed in a hoop barn, with wheat straw bedding provided to Control pigs and rye straw bedding for Rye pigs. Pig performance, including body weight (BW), average daily gain (ADG), average daily feed intake (ADFI), and gain efficiency (G:F) were recorded every 28 days. At the end of the trial, carcass traits such as hot carcass weight (HCW), backfat thickness (BF), and loin eye area (LEA) were measured. Feed samples from each dietary phase were analyzed for nutrient composition, including phosphorus and phytic acid concentrations. Fecal samples from 80 pigs (40 Control and 40 Rye) were collected and analyzed for phosphorus and phytic acid concentration. There were no differences in BW, ADG, ADFI, G:F, or fat-free lean percent of carcass between Control and Rye fed pigs ( p &amp;gt; 0.05). However, carcass yield and LEA were lower in Rye-fed pigs ( p &amp;lt; 0.05). Mortality tended to be lower in Rye-fed pigs ( p = 0.082) probably due to random variation, while morbidity was not different between treatments ( p &amp;gt; 0.05). Phosphorus concentrations in Rye diets were higher across most dietary phases ( p &amp;lt; 0.05), but there were no differences in phosphorus or phytic acid concentrations in the fecal samples between treatments suggesting improved utilization of dietary phosphorus in Rye-fed pigs. In conclusion, replacing 50% of corn with winter hybrid rye in diets for organically-raised growing-finishing pigs did not affect growth performance but reduced carcass yield.

  PublisherOA PDFDOI

• Effects of dietary hybrid rye on quality and consumer eating quality of pork from pigs raised under organic conditions

  Organic Agriculture · 2025-07-16

  articleOpen access

  Abstract Winter hybrid rye has become of interest to organic farmers in the Midwest region of the United States due to its potential for high yields, hardy overwintering, and environmental benefits. We investigated whether inclusion of hybrid rye in swine diets affected quality and consumer eating quality of organic pork. Pigs ( n =500, initial weight=27.8±3.5kg, 10 weeks of age) were assigned to Control or Rye treatments (50 pigs/pen; 5 pens/treatment). Control pigs received corn, soybean meal-based organic diets and rye pigs received diets with organic hybrid rye replacing 50% of the corn in control diets. At market weight (average=127 kg, 23 weeks of age), 40 pigs/treatment were selected for evaluation of carcass and pork quality. A consumer panel consisting of 72 adults conducted sensory evaluations of pork from 16 pigs/treatment. Data were analyzed using the Glimmix or Analysis of Variance procedure of SAS. Measures of carcass (carcass weight and length, dressing %, chill loss, backfat thickness and loin area) and pork quality (pH at 45 min and 24 h, objective color scores of L*, a*, b*, subjective marbling and color scores, and shear force) were not different between treatments (all P &gt;0.13). The consumer panelists did not detect differences in juiciness, off-flavor, or liking ratings of pork between treatment groups (all P &gt;0.35), except a tendency ( P =0.075) of tougher pork from Rye pigs than from Control pigs. These data indicate that replacing 50% of corn with hybrid rye in diets for growing-finishing pigs did not negatively impact quality or consumer eating quality of organic pork.

  PublisherOA PDFDOI

• 25. Weighing benefits and burdens: zinc supplementation strategies for sows and their environmental footprint

  Animal - science proceedings · 2025-10-25

  article1st authorCorresponding
  PublisherDOI

• Organic Camelina Meal as a Replacement for Soybean Meal in Swine Finishing Diets: A Life Cycle Analysis Perspective

  Sustainability · 2025-02-10 · 1 citations

  articleOpen access

  The production of organic meat and dairy products relies on limited organic protein meal supplies. Camelina (Camelina sativa L.) may sustainably increase organic protein meal supplies. Using grain production trial data, research literature, and camelina feeding trial results, greenhouse gas (GHG) emissions and fossil energy impacts were modeled for inclusion of 10% camelina meal in swine finishing diets using life cycle analysis (LCA). Two key grain production scenarios were examined: field trial relay (FTR) camelina and a higher yielding as expected relay (AER) camelina, with a baseline monocrop soybean (MCS). At the grain production stage, the FTR, AER, and MCS scenarios emitted 0.65, 0.43, and 0.13 kg of CO2 eq./kg DM grain harvested, respectively. At the meal production stage, 0.61, 0.40, and 0.15 kg of CO2 eq. were emitted per kg of protein meal from the FTR, AER, and MCS scenarios, respectively. GHG emissions from the finishing phase of pork production were 1.43, 1.38, and 1.31 kg CO2 eq./kg live weight pigs produced for the FTR, AER, and MCS scenarios, respectively. Findings were similar for fossil energy use. The higher environmental burdens from camelina grain production due to reduced yields of both camelina and soybean resulted in negative environmental performance in camelina-amended diets.

  PublisherOA PDFDOI

• 6. Litter origin is associated with gut microbiome composition during tail-biting outbreaks in growing-finishing pigs

  Animal - science proceedings · 2025-08-01

  article
  PublisherDOI

• Piglet birth weight but not the timing of zinc supplementation in gestation diets affects tissue mineral concentrations and gene expression

  Journal of Animal Science · 2025-01-01

  articleOpen accessSenior author

  Sows were supplemented with high dietary zinc (Zn) at different times in gestation to determine effects on piglet tissue mineral concentrations and gene expression. Ten sows per treatment were assigned to dietary treatments: 1) Control-sows fed a corn-soybean meal-based diet containing 206 ppm total supplemental zinc supplied by zinc hydroxychloride from mating to farrowing; 2) Breed-to-Farrow-as Control + additional 147 ppm supplemental Zn as ZnSO4 fed from 5 d post-breeding to farrowing; and 3) Day 110-to-Farrow-as Control + additional 4,079 ppm supplemental Zn as ZnSO4 starting on day 110 of gestation until farrowing. Final supplemental Zn concentrations of the Control, Breed-to-Farrow, and Day 110-to-Farrow treatments were 206, 353, and 4,285 ppm, respectively. Serum, colostrum, and milk were collected from each sow. At farrowing, 2 average birth weight (ABW) and 2 low birth weight (LBW) piglets from each sow were selected for collection of serum and tail samples within 2 d of birth. Liver tissue was collected from 65 piglets that died naturally (n = 35) or were euthanized (n = 30). Blood was collected from a different group of piglets (9 LBW piglets per treatment and 8 ABW Control piglets) for RNA-sequencing to evaluate differentially expressed genes (DEGs) and pathways. Mineral concentration data were analyzed using a generalized linear mixed model and RNAseq data were analyzed using the edgeR program. Diet did not affect mineral concentrations of sow serum, colostrum, and milk (P > 0.05). Mineral concentrations of piglet serum were not influenced by maternal Zn treatment or piglet birth weight. Tail Cu for LBW piglets born to sows fed high Zn tended to be lower than Control piglets (P = 0.082) while piglets of LBW had greater concentrations of Fe (P = 0.018) and Cu (P = 0.031) in tails compared to ABW piglets. Piglets that died naturally had greater hepatic Fe concentrations (P < 0.001) than healthy euthanized piglets. Only 2 to 3 DEGs were noted between Control LBW and LBW piglets born to sows fed high Zn. However, 262 DEGs were identified between LBW and ABW piglets. Genes affected by birth weight were associated with pathways of translation and ribosomal activity. In conclusion, the timing of feeding high Zn concentrations to gestating sows had minimal influence on concentrations of trace minerals in sows and their offspring, while piglet birth weight may have meaningful effects on mineral metabolism and protein synthesis of neonatal piglets.

  PublisherOA PDFDOI

Frequent coauthors

• G. C. Shurson

  University of Minnesota

  98 shared

• Pedro E Urriola

  University of Minnesota System

  56 shared

• Xi Ma

  China Agricultural University

  50 shared

• Xiangfang Zeng

  China Agricultural University

  43 shared

• Xia Hua

  40 shared

• Yuhong Zou

  Feed Research Institute

  40 shared

• Yuting Yang

  Feed Research Institute

  40 shared

• Haidong Sun

  Guangzhou University of Chinese Medicine

  38 shared

Labs

• Department of Animal SciencePI