About

Katharine Stewart is an unpaid Emeritus Professor in the Department of Psychology at NC State University, affiliated with the College of Humanities and Social Sciences. She specializes in applied social psychology, with a focus on end-of-life decision making for individuals and families, as well as sexual health promotion and risk reduction. Dr. Stewart has a background as a medical psychologist and has received multiple NIH research grants and sponsored NIH fellowship grants in the areas of HIV treatment, HIV prevention, and health disparities. Her current research program is centered on end-of-life decision making, and her teaching includes courses in grant writing, psychopathology, and the psychology of anxiety. She has received several awards for her undergraduate and graduate teaching and mentoring, and she actively mentors students, faculty, and academic leaders.

Research topics

• Biology
• Animal science
• Medicine
• Andrology
• Genetics
• Endocrinology
• Internal medicine
• Physiology
• Biochemistry
• Computer Science
• Artificial Intelligence
• Ecology
• Neuroscience
• Obstetrics
• Food science
• Chemistry

Selected publications

• Impact of farrowing crate enrichment strategies on the welfare and performance of sows, suckling piglets, and post-weaned piglets

  Journal of Animal Science · 2025-01-01

  articleOpen access

  In conventional pig production, lactating sows are typically housed in farrowing crates that restrict movement and environmental engagement, raising welfare concerns. Farrowing pens also lack behavioral stimulation for suckling piglets, hindering species-specific behaviors. Environmental enrichment may improve welfare by redirecting behaviors-such as chewing-away from conspecifics in piglets and pen fixtures in sows. However, few studies have explored its effects in farrowing crates, particularly regarding optimal placement within these spatial constraints. This study evaluated the impacts of enrichment strategies on the welfare and performance of 37 lactating sows and their litters from birth through early post-weaning. Sows and litters were divided into three groups: both had access to enrichments (SPE), only piglets had access (PE), and a control group with no enrichments (CON). Point-source objects (PorkyPlays and wooden blocks on rope) were placed 2 d after sows moved into farrowing crates until 2 wk post-weaning. Sow salivary cortisol was collected at four timepoints, and pressure sores were assessed at 8 timepoints from 24 h after crate entry to weaning. Piglet tear stains and skin lesions were recorded throughout the lactation phase. Suckling piglet average daily gain (ADG) was analyzed at days 1 to 7, 7 to 14, and 14 to weaning. In the nursery, salivary cortisol, tear stains, and skin lesions were measured on days 1, 7, and 14 post-weaning, with an additional cortisol sample at day 0 post-weaning. Nursery piglet ADG was analyzed from weaning to day 14 post-weaning. CON sows were more likely to have a pressure sore compared to SPE sows (P = 0.02); PE sows tended to have a higher likelihood of developing a pressure sore than SPE sows (P = 0.097). No treatment effect was found for salivary cortisol of sows or nursery piglets. However, CON piglets had the largest tear stains during lactation (P < 0.001) and nursery (P = 0.001). Treatment affected piglet skin lesions during lactation, with CON piglets having more ear (P < 0.001) and front (P = 0.002) lesions and a higher overall lesion score (P < 0.0001). No treatment effect was found for ADG, piglet crushing, or nursery skin lesions. In conclusion, enrichment strategies in farrowing crates improved piglet skin health and tear stains without affecting performance. Enrichment access for sows tended to reduce pressure sores, suggesting enrichments can enhance welfare in farrowing crate systems.

  PublisherOA PDFDOI

• 243 Effect of electronically controlled floor cooling pads on physiological indicators and semen performance of Duroc boars during the summer months

  Journal of Animal Science · 2025-05-01

  articleOpen accessSenior author

  Abstract The objective of the study was to evaluate the effects of using electronically controlled floor cooling pads(ECP) on boar physiology and semen quality during the summer season in a boar stud in Williamston, North Carolina. One hundred twenty boars(313± 130 days of age) were placed in five zones(24 pens 2.29 x 0.66 m) across two tunnel ventilated barns(244 and 148 boars) and randomly assigned to either CONTROL (n=60; partially slatted concrete floor with no ECP) or ECP (n=60) treatments. Cold water was continuously flushed through the individual ECPS at a flow rate of 9.1 L/min. Cold water was circulated when the temperature sensor, placed on the first outlet pipe for each zone, reached 24.5°C and the controller redirected the system to recirculate the water in the pipes when temperature is at 24°C. The boars were exposed to natural heat stress (daily mean temperature and humidity: 25.7°C; 97.99% and hourly mean peak 34.18°C; 100% respectively) in a period of 90 days from July 4 to October 2, 2024. The physiological indicators of heat exposure taken were respiration rate (RR) and rectal temperature (RT) once daily during the hottest part of the day (13:00-17:00h). Semen was collected at least once a week and was analyzed using MetroSperm for concentration, gram scale for volume and subjective analysis by trained technicians for motility and morphology. Detailed morphology was also done by staining samples with Hancock stain and evaluated using 100x oil immersion. Data collected were evaluated using PROC MIXED for repeated measures in SAS (v.9.4) with the main effects of treatment, barn, boar ID, week and their interactions, using classification (old/young) and zone (assigned variables to denote location in barn) as covariates for RR and RT. Same evaluation was done with main effects of treatment, barn, week, and classification, using rest interval and zone as covariates for semen quality estimates. RR and RT were decreased overall by ECP (P&amp;lt; 0.001), week (P&amp;lt; 0.001) and their interaction (P&amp;lt; 0.001). The zone in the barn across different weeks and treatments also influenced the RR (P&amp;lt; 0.001) with CONTROL boars in the zones farthest from the cool cell having higher RR (mean: Barn A-23.34 breaths/min; Barn C-20.65 breaths/min) compared to ECP boars (mean: Barn A-16.25 breaths/min; Barn C-14.34 breaths/min). The increase in RR in these zones (farthest from cool cells) results from increased environmental temperature ranging from 0.88°C to 1.52°C. There were no differences in semen quality estimates between CONTROL and ECP boars (P &amp;gt;0.05) with the exception of improved total motile and normal sperm on weeks 4 and 7 (P&amp;lt; 0.05). Overall, ECP use during the summer months improved the physiological indicators of heat exposure while having slight improvements on semen quality towards the later part.

  PublisherOA PDFDOI

• Heat stress matters: insights from United States swine producers

  Translational Animal Science · 2025-01-01 · 4 citations

  articleOpen accessSenior author

  Heat stress (HS) is widely recognized by researchers and veterinarians as a major issue impacting swine health, productivity, and welfare, but there is limited understanding of how HS is perceived and managed at the farm level. Therefore, the study objective was to assess U.S. swine farm managers' perceptions of HS impacts, thresholds, and management for multiple pig categories including preweaned pigs, nursery pigs, grow-finish pigs, market pigs, nonpregnant and gestating sows, lactating sows, and mature boars. Sixty-two swine farm managers completed an electronic Qualtrics survey, presented in both English and Spanish, which included questions on perceived HS thresholds, ventilation setpoints, mitigation practices, and environmental management support tools. Respondents rated their agreement with HS impacts on productivity, health, and welfare using a Likert scale, and Pearson's correlations were used to establish relationships between responses. A majority of respondents agreed or strongly agreed that HS negatively affects pig productivity (87.1%), health (83.9%), and welfare (85.5%). However, perceived HS thresholds were variable across pig categories including preweaning pigs (31.22 ± 3.59 °C), nursery pigs (31.46 ± 3.79 °C), grow-finish pigs (28.16 ± 4.27 °C), market pigs (26.22 ± 5.56 °C), nonpregnant sows (27.77 ± 3.81 °C), gestating sows (26.99 ± 3.34 °C), lactating sows (26.71 ± 3.08 °C) and mature boars (26.61 ± 3.99 °C). The standard deviations for reported thresholds ranged from ±3.08 to ±5.56 °C, underscoring the variability in perceptions among respondents. This variability extended to ventilation temperature setpoints with high ventilation temperature setpoints of 24.34 ± 3.75 °C and 25.41 ± 2.80 °C, and low ventilation temperature setpoints of 17.32 ± 3.10 °C and 18.86 ± 2.96 °C for gestation barns and farrowing barns, respectively. Finally, a majority of producers (64.5%) agreed or strongly agreed that a decision support tool for improved HS management would be beneficial to their operation. Producer responses emphasize the need for clearer guidelines and more consistent application of HS management practices to optimize swine health, productivity, and welfare across different production stages.

  PublisherOA PDFDOI

• Early gestation heat stress influences fetal biomarkers indicative of maternal cortisol transfer in pigs

  Scientific Reports · 2025-07-23 · 3 citations

  articleOpen access

  In utero heat stress (IUHS) alters hypothalamic-pituitary-adrenal (HPA) axis development in pigs; however, the mechanisms mediating this effect remain unclear. This study aimed to evaluate cortisol transfer dynamics from the heat-stressed (HS) dam to the IUHS conceptus during early gestation. We hypothesized that gestational HS would modify maternal cortisol secretion and increase conceptus cortisol exposure. Twenty-three gilts were exposed to thermoneutral (TN; n = 11) or HS (n = 12) conditions from gestation d 6 to 33. Maternal vaginal temperature, respiration rate, skin temperatures, and salivary cortisol concentrations were monitored. On d 33, dams were harvested to assess fetal and reproductive tract morphology and collect fetal and placental samples for glucocorticoid and 11β-HSD2 analyses. Heat-stressed gilts exhibited increased (P ≤ 0.01) vaginal temperature, respiration rate, and skin temperatures, but salivary cortisol was similar (P = 0.13). Total and viable fetuses per corpus luteum were reduced (P ≤ 0.05) in HS dams. Fetal tissue cortisone: cortisol tended to be reduced (P = 0.06) and was reduced in IUHS fetus amniotic fluid (P = 0.03). Amniotic fluid cortisone tended to decrease (P = 0.07), while cortisol tended to increase (P = 0.08) in IUHS fetuses. These data suggest IUHS increases fetal glucocorticoid exposure.

  PublisherOA PDFDOI

• 64 Perceptions of U.S. swine producers on the impact of heat stress on herd health, productivity, and welfare

  Journal of Animal Science · 2025-05-01

  articleOpen accessSenior author

  Abstract Heat stress (HS) is widely recognized by researchers and veterinarians as a major issue impacting swine health, productivity, and welfare, but there is limited understanding of how HS is perceived and managed at the farm level. Therefore, the study objective was to assess U.S. swine farm managers’ perceptions of HS impacts, thresholds, and management for various pig categories. Sixty-two swine farm managers completed an electronic Qualtrics survey, presented in both English and Spanish, which included questions on perceived HS thresholds, ventilation setpoints, mitigation practices, and environmental management support tools. Respondents rated their agreement with HS impacts on productivity, health, and welfare using a Likert scale, and Pearson’s correlations were used to establish relationships between responses. A majority of respondents agreed or strongly agreed that HS negatively affects pig productivity (87.1%), health (83.9%), and welfare (85.5%). However, perceived HS thresholds were variable across pig categories including pre-weaning pigs (31.22 ± 3.59°C), nursery pigs (31.46 ± 3.79°C), grow-finish pigs (28.16 ± 4.27°C), market pigs (26.22 ± 5.56°C), non-pregnant sows (27.77 ± 3.81°C), gestating sows (26.99 ± 3.34°C), and mature boars (26.61 ± 3.99°C). The standard deviations for reported thresholds ranged from ±3.34°C to ±5.56°C, underscoring the variability in perceptions among respondents. This variability extended to ventilation temperature setpoints with high ventilation temperature setpoints of 24.34 ± 3.75°C and 25.41 ± 2.80°C, and low ventilation temperature setpoints of 17.32 ± 3.10°C and 18.86 ± 2.96°C for gestation barns and farrowing barns, respectively. Finally, a majority of producers (64.52%) agreed or strongly agreed that a decision support tool for improved HS management would be beneficial to their operation. Producer responses emphasize the need for clearer guidelines and more consistent application of HS management practices to optimize swine health, welfare, and productivity across different production stages.

  PublisherOA PDFDOI

• Commercial boar development and management: a review of strategies

  Translational Animal Science · 2025-01-01 · 1 citations

  reviewOpen access

  While boars constitute a relatively small portion (less than 0.005%) of the total swine herd, they have significant genetic influence on the swine population. An individual boar has the potential to sire thousands of offspring every year, yet when it comes to science-based recommendations for boar development from weaning to puberty, there is little in the way of recommendations. Similarly, the management and nutritional recommendations of today's boar population are based on studies that may not be relevant to current genetics or based on recommendations for gilts and sows. Historically with rapid genetic turnover in boar studs there has been little pressure to produce research in this area. However, with boar studs reporting increasing incidence of lameness and health related removals, rising developmental costs, and a need to maintain herd fertility it has created opportunities to increase the scientific understanding of boar development and management. In this literature review, we aim to overview development and management of commercial boars in the United States and highlight what is understood in the way of science-based research.

  PublisherOA PDFDOI

• PSIV-10 Economic analysis of gilts bred with or without heat-not-serve and the impact on gilts longevity to parity three

  Journal of Animal Science · 2025-05-01

  articleOpen access

  Abstract The objective of this study was to determine a heat-no-service (HNS) impact on total born piglets to parity three and the economic implication on the production system. Sixteen thousand six hundred and forty-three gilts were utilized from a commercial production system. Gilts were sorted by having exhibited signs of estrus or not before breeding and the season first service occurred, with farm used as a random effect. Data were analyzed using PROC GLM to form a regression tested for linear, quadratic, cubic, and quartic effects of service age. A linear effect was observed between service age and estrus (P&amp;lt; 0.001) on total born from first service to parity three. Gilts that exhibited an estrus and were bred on the second estrus or later were observed to have greater total number born (38 pigs vs 32 pigs) to parity three compared to gilts bred on their first estrus. The model predicted the difference in total born through three parities is approximately 6 when gilts are breed on the second estrus or later. An economic model was also developed from the regression to determine marginal potential profit for gilts from entering the facility in the gilt development unit to the end of parity three. This model was compared against the actual data to compare predicted to actual data differences. Also, gilts bred on the second or later estrus had a greater percentage of animals with positive profit for the model (81%) and actual (77%) data compared to the gilts bred on the first estrus model (56%) and actual (72%). Profit through parity 3 was predicted to be $31 greater compared to actual $41 greater profit for gilts with a HNS vs gilts bred on their first heat. The differences in profit for gilts bred on the second or later estrus is related to less production days in the gilt farm to reach parity three and increased number of piglets to parity three and greater retention rates. Further research is needed with large production data sets to develop production and economic models for producers and management to aid in solving on farm issues and increase production efficiencies.

  PublisherOA PDFDOI

• Fetal sex effects on maternal health can now be tested via randomization: A first-in-class illustration in cows on glucoregulatory outcomes

  Theriogenology · 2024

  • Computer Science
  • Artificial Intelligence
  • Obstetrics
  PublisherOA PDFDOI

• 222 Effect of electronically controlled floor cooling pad on thermoregulatory performance of Duroc boars during the summer heat stress period

  Journal of Animal Science · 2024-05-01 · 1 citations

  articleOpen accessSenior author

  Abstract The objective of the study was to evaluate the effects of using electronically controlled floor cooling pad (ECP) to reduce physiological heat stress response during the summer season in a boar stud in Scottsville, Kentucky. Boars (n = 60; 526 ± 188 d of age) were placed in two rows of pens (2.06 x 0.66 m) of a 350 head tunnel ventilated boar barn and were randomly assigned to either CONTROL (n = 30; no ECP) or ECP treatments (n = 30). The ECP had 4.25 L cold water flushed through a group of 5 pads connected to each other, when temperature sensors reached 27°C or every 4 min for sensors placed on 5th pad and 24°C or every 4 min for sensors placed on 1st pad. Boars experienced a natural summer heat stress environment (daily temperature, humidity and dew point: mean = 24.03°C, 87.9%, 21.7°C, hourly mean high = 28.9°C, 83.4%, 25.8°C) for a period of 30 d from July 15, 2023 to August 14, 2023 wherein the cooling pad remained on and were flushing based on the set points mentioned above. Daily physiological measurements included respiration rate (RR), rectal temp (RT) and feed refusal (FR) collected during the hottest part of the day (1300 to1600 h) via counting chest or belly rises, using rectal thermometer and visual estimation, respectively. A mixed model in SAS (v.9.4) including the fixed effects of ECP, week, day, boar ID and their interactions with day in the week included as a random effect was used for the statistical analysis. Both RR and RT were decreased by ECP (P &amp;lt; 0.001), week (P = 0.027 and P = 0.005, respectively) and treatment by week interactions (P &amp;lt; 0.001). The overall RR and RT for boars on ECP (Mean = 15.2 breaths/minute, 38°C) were more stable compared with Control (Mean = 43.4 breaths/minute, 38.4°C). Increased RR (Mean = 55.7 breaths/min; daily high = 164 breaths/minute) and RT (Mean = 38.7°C; daily high = 40°C) were noted in wk 30 and 33 for CONTROL group while ECP group remained stable. The wk 30 and 33 RR and RT are caused by increased environmental temperatures and humidity (hourly mean high: temperature = 28.9°C, humidity = 84.9%, dewpoint = 21°C). FR increased as barn temperatures increased and treatment by week interactions were significant (P &amp;lt; 0.001), with a tendency for ECP to be overall less than CONTROL at P = 0.064. CONTROL boars had greater FR than ECP boars for wk 31 (P &amp;lt; 0.001), 32 (P = 0.001) and tendency for wk 33 (P = 0.098). These results indicate that the ECP effectively reduced the RR, RT and FR across the weeks with greater effects seen during the hottest weeks in the 30-d trial.

  PublisherOA PDFDOI

• PSI-2 Daily thermoregulatory performance patterns of Duroc boars with or without electronically controlled floor cooling pads during the peak summer heat stress period

  Journal of Animal Science · 2024-05-01 · 1 citations

  articleOpen access

  Abstract The objective of the study was to evaluate the daily thermoregulatory pattern of Duroc boars with and without electronically controlled floor cooling pads (ECP) during the summer season in a boar stud at Scottsville, Kentucky. Thirty boars were placed in two rows of pens (2.06 x 0.66 m) of a 350 head tunnel ventilated barn and were randomly assigned to either CONTROL (n = 15; no ECP) or PAD (n = 15; 4.25 L cold water flushed when sensors reached 27°C or every 4 min, whichever occurred first, through a group of 5 pads connected to each other) treatments. Boars experienced natural seasonal heat stress (daily mean temperature = 25.7°C; hourly high temperature = 28.8°C, corresponding relative humidity = 85.4%, corresponding dew point = 26°C) during the period of 4 d wherein the ECP remained on, and flushing based on the setpoints mentioned above. Rectal temperature (RT) and respiration rate (RR) were taken at 600, 830, 1100 1330, 1600, 1830 and 2100 h daily for all 4 d. Two statistical analyses were conducted. The first was a mixed model including the fixed effects of ECP, day, time of measurement and their interactions with boar included as a random effect. Secondly, mixed model periodic regressions were fitted to the RR and RT data. Both RT and RR were impacted by ECP, day, time, and all two and three factor interactions (P &amp;lt; 0.001). The final periodic regression model for RR included the random effect of boar, main effect of ECP, interaction of ECP and day, single phase sine/cosine and 2-phase cosine variables, the interaction with the single 2 and 3 phase sine/cosine variables with day (P &amp;lt; 0.001). The periodic regression results indicate that the response of the ECP to reduce RR were consistent relative to the time of the day (mean of 57.5 breaths/min versus 18.9 breaths/min, P &amp;lt; 0.001) but the overall response in RR relative to time of day was variable for the four days. The final model for RT using periodic regression included the random effect of boar, ECP, single-phase sine and cosine and three-phase sine variables (P &amp;lt; 0.001) and interaction of single-phase sine by ECP (P = 0.001) and interaction of the three-phase sine with day. The interaction of the ECP by single phase sine interaction was due to an increase in temperature from 600 to 1330 for control boars (0.21°C) versus no change for boars on the ECP. The ECP reduced RT at all measurement times, a lesser extent from 600 to 1100 (0.31°C to 0.37°C) and greater extent from 1330 (0.59°C) and 1600 h (0.63°C) and 2100 (0.67°C). The impact of the ECP to reduce RR and RT varied from day to day with greater effects on the days with higher barn temperatures.

  PublisherOA PDFDOI

Frequent coauthors

• A. P. Schinckel

  Purdue University System

  24 shared

• Theresa Casey

  Purdue University West Lafayette

  23 shared

• B. T. Richert

  Purdue University West Lafayette

  21 shared

• Kayla M Mills

  Agricultural Research Service

  18 shared

• Drew Lugar

  Illinois State University

  14 shared

• Aridany Suárez-Trujillo

  Berry College

  12 shared

• F. A. Cabezón

  11 shared

• Jay S Johnson

  Agricultural Research Service

  11 shared

Awards & honors

• several awards for her undergraduate and graduate teaching a…