About

Professor Ryan N. Dilger leads the Nutrition, Health, and Neuroscience Laboratory at the University of Illinois Urbana-Champaign, where his research sits at the intersection of animal agriculture and biomedical science. His laboratory focuses on understanding how diet influences metabolism, immunity, and brain development, with a particular emphasis on the domestic pig as a translational model. The lab's work spans evaluating feed ingredients, immune function, and disease resilience in pigs and other non-ruminant species, as well as studying brain development and cognitive outcomes in young pigs. By combining controlled nutrition studies with advanced imaging, behavioral testing, and analytical chemistry, the research aims to generate data that improves animal health and performance while also informing nutrition strategies for human infants and children. The research program under Professor Dilger is organized around two core areas linking diet, health, and brain function, focusing primarily on the role of early-life diet in shaping the microbiota-gut-brain axis. In the Nutrition and Health area, the lab evaluates feed ingredients, bioactive compounds, and dietary strategies that influence growth, gut function, and immune responses in pigs and other non-ruminant species, emphasizing practical feeding programs, disease challenge models, and resilience measures relevant to producers and the feed industry. In the Nutrition and Neuroscience area, the lab uses the young pig as a model to study how early-life nutrition affects brain structure, myelination, and cognition. Techniques such as MRI, histology, and behavioral paradigms like novel object recognition are employed to examine how specific nutrients and dietary patterns influence neurodevelopmental trajectories. Professor Dilger's lab brings together faculty, staff, postdoctoral scholars, and students from animal sciences, nutritional sciences, neuroscience, and related fields. Trainees gain comprehensive experience in study design, animal handling, sample collection, imaging, data analysis, and scientific communication. Alumni from the group have progressed into academic positions, industry research and development, and professional programs in nutrition, veterinary medicine, and related fields.

Research topics

• Biology
• Psychology
• Neuroscience
• Medicine
• Developmental psychology
• Physiology
• Computer Science
• Pathology
• Biochemistry
• Endocrinology
• Internal medicine
• Genetics
• Biotechnology
• Computational biology
• Bioinformatics
• Risk analysis (engineering)
• Engineering
• Data science
• Business
• Art
• Systems engineering
• Food science
• Immunology

Selected publications

• 164. Modulation of Growth and Immune Function by Soy Saponins in Poultry

  Journal of Animal Science · 2026-04-01

  articleOpen accessSenior author

  Abstract Soybean is a key plant-protein source often included in poultry diets for its nearly complete amino acid profile. Outside of protein, soybeans contain a multitude of bioactive compounds that have garnered attention for their potential immunomodulatory effects. Soy saponins are one such compound that may have beneficial anti-inflammatory, antioxidative, and antiparasitic properties. In this study, 810 male Ross 308 chicks at 2-d post-hatch were allotted to 1 of 9 treatment groups with 10 birds in 10 replicate cages for treatments 1-6 and 7 birds in 10 replicates for treatments 7-9. This 28-d feeding study was conducted in a 3 × 3 factorial arrangement with factors including: 1) saponin supplementation (3 levels; no supplementation, soy saponin supplementation at 250 mg/kg active soy saponins, or yucca-derived saponin supplementation at 250 mg/kg commercial yucca saponin product) and 2) challenge status (3 levels; unchallenged, lipopolysaccharide (LPS) challenged, or Eimeria coccidiosis vaccine challenged). After a 15-d acclimation period and 24-h feed withdrawal, birds in Eimeria-challenged groups (treatments 7-9) were orally gavaged with a commercial coccidiosis vaccine at 5× the recommended dose while control group birds (treatments 1-3) received a sham gavage. Cloacal temperatures, blood, and intestinal tissue samples were collected at peak infection [6 d post-inoculation (DPI)] and at study termination (13 DPI). On study d 22, birds in LPS-challenged groups (treatments 4-6) received an intraperitoneal injection of E. coli O127:B8 LPS at 2 mg/kg body weight (BW) while control birds received a sham injection. Cloacal temperatures and blood were collected at 0-, 2-, and 4-h post-injection while intestinal tissue samples were only collected at 0- and 2-h. All data were analyzed by ANOVA using the MIXED procedure of SAS. Cloacal temperatures were not affected (P > 0.05) by treatment at any of study time-points. Coccidiosis vaccine challenge status was confirmed via oocyst counts, but no differences (P > 0.05) were observed for oocyst excretion between infected treatments. Eimeria-challenged birds had reduced (P < 0.05) feed intake (FI) and BW gain (BWG) during the peak infection period (d 14-21), resulting in increased (P < 0.05) feed conversion ratios (FCR) compared with the non-challenged control treatment. During this period, both soy and yucca saponin supplementation improved (P < 0.05) FCR in Eimeria-challenged birds compared with challenged birds on a control diet. LPS challenge had variable effects on FI and BWG post-challenge (d 21-28) but no significant differences (P > 0.05) on FCR. Overall, saponin supplementation elicited the most evident benefits in Eimeria-infected birds, improving their FCR during peak infection. Whether this can be explained by their purported anti-inflammatory and antioxidative properties remains to be seen.

  PublisherOA PDFDOI

• Effects of dietary saponin and polyphenol supplementation in broiler chickens exposed to multiple mild stressors of cyclic elevated ambient temperature, feed withdrawal, and coccidiosis infection

  Poultry Science · 2026-03-18 · 1 citations

  articleOpen accessSenior author

  Broilers are commonly exposed to numerous environmental and immunological stressors in a production setting. In this study, two botanical feed additives were evaluated for their effects on growth performance, antioxidant defenses, and intestinal health in stressed broilers. To achieve a multiple mild stressors challenge, birds underwent a 12-h feed withdrawal prior to a coccidiosis vaccine challenge on d 15 of the study, which was designated as 0 d post-inoculation (DPI). Additionally, birds were exposed to cyclic elevated ambient brooder temperatures during the grower phase. A total of 420 male Ross 708 chicks at 2 d post-hatch were assigned to 1 of 5 treatment groups with 7 birds allotted to each of 12 replicate cages. The 42-d study (starter d 0-14, grower d 14-28, finisher d 28-42) was conducted with treatments including: 1) control diet + birds not exposed to stressors (NC), 2) control diet + birds exposed to stressors (PC), 3) PC + 500 mg of Micro-Shield/kg of diet in the starter phase only (MS), 4) PC + 500 mg of Micro-Shield/kg diet in the starter, grower, and finisher phases (MSall), and 5) PC + 500 mg of Micro-Shield/kg diet in the starter phase + 250 mg of Micro-Aid/kg diet in the grower and finisher phases (MS+MA). All data were subjected to a 1-way ANOVA using the MIXED procedure of SAS with results considered significant when P < 0.05. Birds exposed to stressors had impaired growth performance during the grower phase compared with birds in the NC group (P < 0.05). On 6 DPI, birds in the MS+MA treatment had the highest (P < 0.05) levels of catalase in blood serum, potentially indicating higher antioxidant capacity. While birds in the NC treatment had the highest gene expression of zonula occludens-1 (ZO-1) in jejunal mucosa tissue on 6 DPI (P < 0.05), MS+MA birds had similar ZO-1 expression compared with NC birds. These results suggest botanicals may confer health benefits in broilers experiencing environmental and immunological stressors.

  PublisherDOI

• A new way of thinking about soybean meal - its impact on swine respiratory disease and, specifically, PRRSV mortality

  AASV Annual Meeting · 2026-02-15

  article1st authorCorresponding
  PublisherDOI

• 298. Award Talk: Developmental Impacts of Early-life Rearing Environment and Handling on Growth Performance, Immune Activity, and Stress Responses in Pigs

  Journal of Animal Science · 2026-04-01

  articleOpen accessSenior author

  Abstract Stressors are stimuli that disrupt physiological homeostasis, and exposure to stress during early life can influence the maturation of neuroendocrine, immunological, behavioral, and physiological stress responses. In pigs, early experiences involving maternal environment and caregiver interaction occur during a critical developmental window and can result in lasting negative effects. Therefore, this study examined how early-life stressors impact growth, immune function, circulating cortisol, coping strategies, and behavior in young pigs. This study utilized a 2 × 2 factorial arrangement including rearing environment [sow-reared (SR) or artificially-reared (AR)] and handling (handled for 2 minutes per day or handled once a week) as experimental factors. Therefore, 72 pigs (n = 38 gilts and 34 boars) were allotted on postnatal day (PND) 2 to 1 of 4 treatments based on litter of origin and body weight (BW): 1) SR-D (sow-reared, daily handling); 2) SR-W (sow-reared, weekly handling); 3) AR-D (artificially-reared, daily handling); and 4) AR-W (artificially-reared, weekly handling). Artificially-reared pigs were housed individually with ad libitum access to milk replacer, while sow-reared pigs were group-housed with their littermates and received all nutrients from the sow. On PND 21, rearing environment and handling interventions ended, and pigs were transferred to nursery pens according to treatment group. Body weight was recorded according to the assigned handling treatment from PND 2-21 and subsequently measured weekly and analyzed on a pen basis from 21-35. The study concluded on PND 35 following euthanasia of all pigs. Data were analyzed using a 2-way ANOVA with the MIXED procedure of SAS. During PND 2-21, AR pigs had greater (P &amp;lt; 0.05) BW gain than SR pigs and subsequently had higher BW on PND 21 and 35. However, SR pigs exhibited improved (P &amp;lt; 0.05) feed efficiency during PND 21-35 compared with AR pigs. The AR pigs displayed elevated (P &amp;lt; 0.05) cortisol on PND 7 and 28 but had decreased (P &amp;lt; 0.05) cortisol concentrations on PND 22, compared with SR pigs. On PND 35, daily-handled pigs had increased (P &amp;lt; 0.05) duodenal mRNA expression of TNF-α, ZO-1, and occludin compared with weekly-handled pigs, while AR pigs had increased ileal (P &amp;lt; 0.05) IFN-γ and IL-1β expression compared with SR pigs. During a tonic-immobility test to assess stress resiliency, AR-W pigs had the longest (P &amp;lt; 0.05) latency to first escape attempt compared with all other treatments. Handling effects were observed during the human approach test, as W pigs had the longest (P &amp;lt; 0.05) latency to approach compared with D pigs. Following the transition to group housing, AR-D pigs spent more (P &amp;lt; 0.05) time nosing conspecifics than SR-D and AR-W pigs. In conclusion, early-life rearing environment and handling frequency influenced pigs’ growth, immune response, behavior, and cortisol concentrations.

  PublisherOA PDFDOI

• Effects of Human Lactoferrin (effera ^® ) at Two Doses versus Bovine Lactoferrin on the Adult Gut Microbiome and Fecal Short-Chain Fatty Acids: A Randomized, Double-Blind Trial

  medRxiv · 2026-01-02

  articleOpen access

  Abstract Background/Objectives Human lactoferrin (hLF) is glycoprotein of commercial interest as a food ingredient for gut health. Here, we report an exploratory analysis evaluating the effects of Helaina hLF (effera ® ), produced by Komagataella phaffii , on the adult gut microbiome and fecal metabolites in comparison to bovine LF (bLF). Methods In a randomized, double-blind, parallel-arm, controlled trial, 66 healthy adults received either high-dose (HD) effera ® (3.4 g/day), low-dose (LD) effera ® (0.34 g/day), or bLF (3.4 g/day) supplementation for 28 days. Fecal samples were collected at baseline (Day 0), Day 28, Day 56, and Day 84 and analyzed for microbial diversity, taxonomic shifts, and volatile fatty acids (VFA). Results Alpha-diversity remained stable across all groups. Beta-diversity showed no main effect of treatment; however, bLF was associated with significant visit-related shifts, as assessed by weighted UniFrac. At the phylum level, significant changes associated with effera ® were observed, including decreases in Bacillota (LD) and Verrucomicrobiota (HD), and notable genera increases in Lachnospira , Paraprevotella , and Faecalibacterium (HD), while bLF was associated with an increase in Roseburia . Both effera ® and bLF were associated with decreases in Blautia and Dorea . VFA analysis revealed that bLF increased absolute total short-chain fatty acids (SCFAs) and branched-chain fatty acids (BCFAs) concentrations, while both effera ® groups produced proportional changes in SCFAs, individual BCFAs, and acetate. Conclusions In healthy adults, effera ® supplementation promoted a proportional increase in acetate and supported potentially beneficial taxa while maintaining microbial diversity, without disrupting community structure. (clinicaltrials.gov: NCT06012669 ).

  PublisherOA PDFDOI

• Temporal effects of a botanical feed additive and experimental housing methods in broilers exposed to an acute feed withdrawal period prior to coccidiosis inoculation

  Poultry Science · 2026-04-13

  articleOpen accessSenior authorCorresponding

  In this study, a commercial feed additive [Micro-Shield™ (MS); DPI Global, Porterville, CA] and experimental housing methods were evaluated for their temporal effects on endogenous antioxidants, growth performance, and intestinal health in broilers. The 30-d study (starter d 0-14, grower d 14-30) was conducted in a 2 × 4 factorial arrangement with factors including 1) housing method [2 levels; battery cages (BC) with raised-wire flooring or floor pens (FP) with fresh pine shavings] and 2) dietary treatment [4 levels; 1) control diet fed to birds not exposed to stressors (NC), 2) control diet fed to birds exposed to stressors (PC), 3) PC + 1,000 mg of MS/kg diet in the starter phase + 500 mg of MS/kg diet in the grower phase (MSL), and 4) 1,000 mg of MS/kg diet in the starter and grower phases (MSH)]. A total of 720 male Ross 708 chicks were assigned to 1 of 8 treatment groups: BCNC, BC-PC, BC-MSL, BC-MSH, FP-NC, FP-PC, FP-MSL, or FP-MSH. Treatment groups raised in BC or FP were allotted to 10 or 8 replicates, respectively, each housing 10 birds. A multiple mild stressors challenge was imposed by birds undergoing a 12-h feed withdrawal prior to a coccidiosis vaccine challenge on study d 15, which was designated as 0 d post-inoculation (DPI). All data were analyzed by a 2-way ANOVA using SAS and effects were considered significant when P < 0.05. During the grower phase, the FP-NC treatment had the highest (P < 0.05) BWG compared with all other treatments. On 6 DPI, jejunal gene expression of IFN-γ, IL-1β, and IL-10 was highest (P < 0.05) in FP-MSH birds compared with all other treatments. On 9 DPI, there was a main effect of dietary treatment where the MSH treatment had higher (P < 0.05) serum catalase levels compared with its counterparts. These results suggest that MS supplementation, experimental housing method, and their interaction influence growth performance and overall health outcomes in experimental settings.

  PublisherDOI

• Establishing an experimental challenge model in broiler chickens exposed to multiple mild stressors of cyclic elevated ambient temperature, feed withdrawal, and coccidiosis infection

  Poultry Science · 2025-12-16 · 1 citations

  articleOpen accessSenior author

  Broilers routinely experience environmental and immunological stressors in commercial production settings; however, there is limited literature evaluating their combined effects. Therefore, our objective was to assess the synergistic effects of elevated ambient temperature, feed withdrawal, and coccidiosis infection on broiler growth performance, carcass characteristics, and health. The 43-d study (starter d 0-15, grower d 15-29, finisher d 29-43) was conducted in a 2 × 2 × 3 factorial arrangement with factors including 1) environmental status (thermoneutral or cyclically elevated brooder temperature), 2) feed withdrawal status (0- or 12-h withdrawal prior to vaccine challenge), and 3) coccidiosis vaccine challenge on d 16 [0 × (non-challenged), 3 ×, or 5 × challenge). Therefore, 360 male Ross 708 chicks were assigned to 1 of 12 treatments with 6 birds allotted to each of 5 replicate cages per treatment (n = 5). Day of inoculation was designated as 0 d post-inoculation (DPI). A 1-way ANOVA was used for the starter growth phase, whereas a 3-way ANOVA was utilized for the grower growth phase, liver weights, and carcass characteristics. No statistical analyses were applied to finisher performance data. Birds that received a 3 × or 5 × Eimeria challenge had a lower (P < 0.05) body weight gain (BWG) and feed intake (FI) during the grower phase compared with sham-inoculated birds. Additionally, on 6 DPI, birds that received a 3 × or 5 × challenge had higher (P < 0.05) relative liver weights compared with sham-inoculated birds. On 6 DPI, there was a 2-way interaction (P < 0.05) between vaccine challenge dose and feed withdrawal status where birds that received a 3 × vaccine dose and underwent a 12-h feed withdrawal had similar fluorescein isothiocyanate-dextran (FITC-d) serum concentrations compared with birds challenged with a 5 × vaccine dose. Overall, these results suggest that the combination of cyclically elevated temperatures, a 12-h feed withdrawal period prior to Eimeria inoculation, and a 5 × vaccine dose elicited a practical experimental challenge in broilers.

  PublisherDOI

• Increased Circulating Interleukin Concentrations in Type 2 Diabetes: A Systematic Review and Meta‐Analysis

  Obesity Reviews · 2025-06-13 · 3 citations

  reviewOpen accessSenior author

  OBJECTIVES: This work aimed to quantitatively evaluate circulating interleukin concentration data available for patients with Type 2 diabetes. METHODS: We performed a systematic review using PubMed, Web of Science, and the Cochrane Library. Original studies reporting data on circulating interleukin concentrations in at least one group of patients with Type 2 diabetes (obese Type 2 diabetes [OBD], overweight Type 2 diabetes [OWD], or lean Type 2 diabetes [LD]) and healthy weight controls (HWCs) were included. Data were extracted from 43 included studies uniquely encompassing 2646 patients with Type 2 diabetes and 6605 HWCs by independent investigators. We used a random-effects model to pool data in the Comprehensive Meta-Analysis Version 2 software. Effect sizes (ESs) were calculated as the standardized mean difference in interleukin concentrations between groups and then transformed into Hedge's g statistic. RESULTS: Our results revealed higher circulating concentrations in patients with Type 2 diabetes compared with HWCs, including IL-4, IL-6, IL-17, and IL-18. When stratified by BMI subgroups, all patients with Type 2 diabetes displayed elevated IL-6 concentrations compared with HWCs, with OBD patients having the highest ES, followed by OWD and LD. Similar to the overall results, higher interleukin concentrations in different BMI subgroups of patients with Type 2 diabetes were observed compared with HWCs in IL-4 (OWD), IL-17 (LD), and IL-18 (OBD, but not OWD). CONCLUSION: Meta-analysis outcomes demonstrated higher circulating concentrations of IL-4, IL-6, IL-17, and IL-18 in patients with Type 2 diabetes, strengthening the clinical evidence that Type 2 diabetes is accompanied by a systemic inflammatory response.

  PublisherOA PDFDOI

• 212 Impact of rearing environment and handling on pre- and post-wean pigs ability to cope with stress

  Journal of Animal Science · 2025-05-01

  articleOpen accessSenior author

  Abstract Stressors are factors that disrupt homeostasis, in pigs this includes challenges in sow management, human interaction, and weaning. These stressors typically occur in the first month of life, compromising welfare and leading to decreased growth and increased mortality. This study aimed to investigate the impact of early-life stressors on pig growth, immune response, and the ability to cope with these stressors. The study was conducted as a 2 x 2 factorial design with factors including rearing environment [2 levels; sow-reared (SR) or artificially-reared (AR)] and handling (2 levels; handled for 2 minutes per day or handled once a week). Therefore, 72 pigs (38 gilts and 34 boars) were allotted to 1 of 4 treatments on postnatal day (PND) 2 based on their litter of origin and body weight (BW): 1) SR-D (sow-reared, daily handling); 2) SR-W (sow-reared, weekly handling); 3) AR-D (artificially-reared, daily handling); and 4) AR-W (artificially-reared, weekly handling). Artificially-reared pigs were housed individually and had ad libitum access to reconstituted milk replacer, while sow-reared pigs were group-housed with their littermates and received all nutrients from the sow. On PND 21, rearing environment and handling interventions ended, and all pigs were transferred to nursery pens according to their original treatment groups. From PND 2-21, BW was recorded depending on the assigned handling treatment. From PND 21-35, BW was recorded weekly, and growth performance was assessed on a pen basis. On PND 35, all pigs were euthanized, and the study was terminated. Data were analyzed using a 2-way ANOVA with the MIXED procedure of SAS. Pigs that were AR exhibited higher (P &amp;lt; 0.05) average daily gain from PND 2-21. Subsequently, AR pigs had the heaviest (P &amp;lt; 0.05) BW on PND 21 and 35 compared with SR pigs. However, SR pigs exhibited higher (P &amp;lt; 0.05) feed efficiency during PND 21-35 compared with AR. During a tonic-immobility test assessing stress resiliency, AR-W pigs had the longest (P &amp;lt; 0.05) latency to first escape attempt compared with all other treatments, indicating greater stress-coping abilities. Furthermore, pigs that underwent daily handling exhibited more (P &amp;lt; 0.05) total escape attempts and time spent performing escape attempts. As a classic marker of stress, fecal secretory IgA concentrations were highest (P &amp;lt;0.05) in SR pigs when compared with AR pigs on PND 21. On PND 28, AR-W pigs had increased (P &amp;lt; 0.05) cortisol concentrations compared with all other treatments. Furthermore, there was a main effect of rearing with AR pigs experiencing increased (P &amp;lt; 0.05) cortisol on PND 7 and 28, but decreased (P &amp;lt; 0.05) cortisol on PND 22, compared with SR pigs. In conclusion, early-life rearing environment and handling influenced growth and stress response metrics, but did not impact intestinal health.

  PublisherOA PDFDOI

• In vitro fermentation characteristics of dietary fibers using fecal inocula from dogs fed a canned diet and treated with metronidazole

  Frontiers in Veterinary Science · 2025-10-29 · 1 citations

  articleOpen access

  Introduction Metronidazole is a potent antibiotic often prescribed to treat gastrointestinal enteropathies; however, it is known to induce loose stools, negatively alter the fecal microbiome, and affect fecal metabolite production. Dietary intervention may aid in post-antibiotic recovery; however, little research has been conducted on the potential of fiber utilization for microbial recovery in canines. Methods Using an in vitro fermentation assay, the objective of this study is to investigate the fermentation characteristics of dietary fibers using fecal inocula from dogs treated with metronidazole. Four healthy male beagles (age = 1.62 ± 0.02 year) were fed a commercial canned diet for 2 weeks, then administered metronidazole (20 mg/kg BW BID) for 2 weeks. Fresh fecal samples were collected at weeks 2 (before antibiotic treatment; ABX−) and 4 (after antibiotic treatment; ABX+), stabilized in a 20% glycerol solution, and then frozen. On the day of in vitro fermentation, feces from each time point were thawed and used to inoculate the tubes. At baseline and after 6, 12, and 18 h of fermentation, pH, short-chain fatty acids (SCFA), and microbiota were measured. Blank-corrected changes from the baseline data were analyzed using repeated measures and the MIXED procedure in SAS 9.4, with significance set at a p value &amp;lt;0.05. Results Pectin fermentation reduced ( p &amp;lt; 0.001) pH and increased ( p &amp;lt; 0.001) SCFA over time, but the responses were lower ( p &amp;lt; 0.001) in ABX+ than in ABX−. Beet pulp fermentation also reduced ( p &amp;lt; 0.001) pH and increased ( p &amp;lt; 0.001) SCFA over time. The pH change was small between inoculum sources, but SCFA were different ( p &amp;lt; 0.001) between ABX+ and ABX−. Chicory pulp fermentation reduced ( p &amp;lt; 0.001) pH over time, with greater ( p &amp;lt; 0.01) reductions in ABX+ than in ABX−. Chicory pulp fermentation increased SCFA but had different patterns depending on the inoculum source. Metronidazole altered microbiota populations by reducing bacterial alpha diversity ( p &amp;lt; 0.001). Analysis of bacterial beta diversity revealed separate clusters in dogs based on metronidazole administration. Beta diversity analysis also showed that tubes containing chicory pulp clustered separately from those containing other fibers. The relative abundance of over 50 bacterial genera differed ( p &amp;lt; 0.05) among the inoculum sources. Discussion In summary, interesting fermentation patterns were observed in response to varying fiber sources, allowing for improved insights into their potential abilities in antibiotic-treated dogs.

  PublisherOA PDFDOI

Frequent coauthors

• Austin T. Mudd

  University of Illinois Urbana-Champaign

  68 shared

• Sharon M. Donovan

  University of Illinois Urbana-Champaign

  59 shared

• Stephen A. Fleming

  Traverse Biosciences (United States)

  59 shared

• Brian M. Berg

  Mead Johnson (United States)

  54 shared

• Rodney W. Johnson

  University of Illinois Urbana-Champaign

  35 shared

• Lindsey S. Alexander

  25 shared

• Nicole C. Roy

  23 shared

• Brooke N Smith

  23 shared

Education

• PhD, Animal Sciences

  University of Illinois System

  2007

• MS, Animal Sciences

  Purdue University

  2004

• BS, Animal Sciences

  Purdue University

  2001