No description available.

No description available.

No description available.

<p>Two experimentswere  conducted  using  pigs  at different  life stages to  determine  the  effects  of dietary  tryptophan  and  water  delivered  oregano  essential  oil  on growth performance, rectal temperature, water use,intestinal integrity and gene expression of biomarkers in the face heat or transport stress. In the first experiment, 192 grow-finish pigs were used to investigate the effects of  water  supplementation  of  oregano  essential  oil  (OEO)  on  growth  performance,  water  intake, rectal temperature, intestinal integrity, and expression of genetic biomarkers during an acute heat challenge. Pigs were randomly allotted to 2 X 2 factorial arrangement of treatments with pigs being heat  stressed  or  not  and  being  supplemented  with  OEO  or  not with 8  replicate  pens  of  each treatment  with  6  pigs/pen  (4  barrows,  2  gilts  per  pen).  Water  treatments  were administered immediately, with  dosing at  47 μL/L of OEO. One-half  of  the  pigs  on  each  water  treatment remained under thermoneutral conditions (TN; 21.1C), while the other half was subjected to a 3 d diurnal, acute heat stress (HS) with 12 hours at 33.3 oC (7AM-7PM) and 12 hours at 26.7oC (7PM-7AM). Three days post-HS, temperatures were reduced back to TN for the rest of the study, and pigs remained on their water treatments. Rectal temperatures were collected in the morning and evening  of  the  heat  stress  period  on  one  barrow  and  one  gilt  in  each  pen. Jejunal  tissue was collected for subsequent histological examination and determination of gene expression. All data were  analyzed  using  the  GLM  procedure  of  SAS  (ver.  9.4).  Pigs  subjected  to  heat  stress  had reduced ADG (P < 0.003) and G:F (P < 0.008) during the 3d heat stress compared to pigs reared under thermoneutral conditions. However, post-heatstress, heat stressed pigs had compensatory gain resulting in increased ADG (P < 0.001) and G:F (P < 0.001) compared to thermoneutral reared pigs.   Overall,  there  was an  interaction  (P  <  0.006)  observed  between  water  and  heat  treatment with  OEO  increasing  ADG  in  thermoneutral  pigs  but  not  in  heat  stressed  pigs.  Similarly, interactions  between  water  and  heat  treatment  were  observed  for  ADFI  during  heat  stress  (P  < 0.004),  post  heat  stress  (P  <  0.01),  and  overall  (P  <  0.004)  from  increasing  OEO  intake  in thermoneutral pigs but not in heat stressed pigs. Rectal temperatures were higher (P < 0.001) for heat stressed pigs at the end of d 1 and 2 of the acute heat challenge compared to TN housed pigs. Pigs exposed to HS also used more water than pigs housed in a thermoneutral environment (P < 0.002). There were no differences between villi height, crypt depth or VH:CD between treatment groups  (P  >0.05).  There  was  also  no  difference  in  TP53  and  CDKNA1  gene  expression  among treatments (P > 0.10). In the second experiment, 36 barrows were used in an 18d experiment to investigate the effects of pre-weaning tryptophan supplementation on performance and intestinal integrity following  weaning  with  or  without  transport  stress  at  weaning.  Pigs  were  randomly allotted to 2 X 2 factorial arrangement of treatments of pre-weaning tryptophan supplementation or not and weaning transport or not. Pigs on the tryptophan treatment received 0.35, 0.45, and 0.55 g Trp/d in 5 day intervals, beginning 15 d prior to weaning.Tryptophan was dissolved in chocolate milk and administered by oral gavage with control pigs receiving milk only. At weaning, 4 pigs from each pre-weaning treatmentwere euthanized for collection of jejunal tissue.  Of the remaining pigs, half the pigs oneach treatment were transported for 12 h, and half were moved into individual pens  with  no  transport.  Following  transport,  all  pigs  were  individually  housed  and  provided  ad libitum  access  towater  andfeed  from  a  common  diet.  On  d  3  post-weaning,  all  pigswere euthanized for collection of jejunal tissue. Jejunal tissue was used for histological examination and for determination of gene expression. All data were analyzed using the GLM procedure of SAS (9.4).  No  effects  of  Trp  supplementation  were  observed  on  pre-weaning  (P  >  0.10)  growth. Pig BW and ADFI were unaffected (P > 0.10) by Trp supplementation and transport at weaning. Post-weaning, there was a tendency (P < 0.06) for an effect of transport on ADG as transported pigs lost weight in the 3 d post-weaning period while non-transported pigs gained slightly. Gain:Feed post-weaning  was  lower  (P  <  0.04)  for  transported  pigs  compared  to  non-transported  pigs.  No differences  were  observed  for villus base  and  mid  width,  villus  height,  crypt  depth  or  villus height:crypt   depth.   There   was   a   tendency   for   an   interaction   of   transportation   and   Trp supplementation  (P  <  0.06)  on  villi  base  width  driven  by  an  increased  villus  width  in  non-transported pigs given supplemental Trp but a decrease in villus width in transported pigs given supplemental Trp.These results conclude that these alleviating agents had minimal effects when pigs  were  stressed, however TN grow-finish pigs  benefitted  from  OEO  water  supplementation among growth performance.</p>

Animal welfare is a major concern among livestock producers in the U.S. Heat stress, particularly, compromises animal welfare and productivity, causing >$2B annual economic loss to producers. The presence of toxic alkaloids within tall fescue (Schedonorus phoenix syn Lolium arundinaceum, syn Festuca arundinacea) plants induces a complex of disorders collectively known as fescue toxicosis. Summer slump, a reduction in animal performance due to heat stress, is common and evident of the symptoms. Various techniques for assessing animal physiological and behavioral responses to heat stress were explored in this dissertation, with particular emphasis on fescue toxicosis and its mitigation strategies. In the first study, the physiological and behavioral responses of heifers was evaluated when grazing either toxic tall fescue with wildtype endophyte (WE) or tall fescue with a novel endophyte (NE). Heifers (n = 24) were assigned to either WE or NE pastures for a 56-d grazing study during the summers of 2020 and 2021. Heifer average daily gain (ADG), intravaginal temperature, and degree of hair shedding were recorded during the grazing period. Blood samples were collected through coccygeal venipuncture and hair was collected from the left rump for cortisol analysis. Ear, tail, and hoof temperatures were collected for each heifer using an infrared thermal imaging camera. In 2020, heifers that grazed NE tall fescue had greater (P = 0.0160) ADG over the season (0.22 vs. 0.12 kg day-1). Hair retention score was greater (P = 0.0029) for heifers that grazed WE tall fescue compared to heifers that grazed NE tall fescue across both years. Heifers that grazed WE tall fescue had decreased ear skin temperature (P = 0.0001), tail skin temperature (P = 0.0058), and hoof surface temperature (P = 0.0075) compared to heifers that grazed NE. Heifers that grazed WE had 0.3-0.9 ºC hotter intravaginal temperatures than heifers that grazed NE, especially during daytime. Hair cortisol levels of heifers that grazed WE tall fescue were greater (P < 0.0001) compared to hair cortisol levels of heifers that grazed NE tall fescue. From 1200h-1700h each day, heifers that grazed WE tall fescue spent 1.5 more (P = 0.0003) hours standing and 0.9 fewer (P = 0.0402) hours lying down compared to heifers that grazed NE tall fescue. These results suggest that heat stress and other physiological changes in heifers grazing WE tall fescue could be mitigated by renovating pastures with NE tall fescue that does not impose any negative effects on grazing animals. The second study explored the potential benefits of consuming condensed tannins as a means of negating the effects of toxic alkaloids in tall fescue. Twelve fall-born steers were assigned to one of the two diet supplement treatments - sericea lespedeza pellets (LES) or sericea lespedeza pellets mixed with polyethylene glycol (LES+PEG) for 12 weeks during the summers of 2020 and 2021. The LES+PEG treatment served as a positive control since polyethylene glycol binds tannins, rendering them inactive in the gastrointestinal system. Animal body weight (BW), hair retention score (HRS), rectal temperature, and thermographic images were collected every 4 weeks. Hair and blood samples were also collected for cortisol analysis. Fecal and urine samples were collected and analyzed for total ergot alkaloid (TEA) concentration. Steers on LES had greater (P = 0.0033) ADG compared to steers on LES+PEG in 2021, but not in 2020 (P = 0.8707). In 2021, HRS was greater (P < 0.05) for steers fed LES+PEG compared to steers fed LES. In 2020, ear skin temperature (P < 0.0001) and hoof surface temperature (P = 0.0382) was greater in steers on LES compared to steers on LES+PEG. Rectal temperatures were lower (P = 0.02905) for steers fed LES compared to steers fed LES+PEG in 2021. Plasma cortisol levels did not differ (P ≥ 0.1566) between LES and LES+PEG treatments for both years. In 2020, hair cortisol levels did not differ (P = 0.8295) between treatments while in 2021, the hair cortisol level of steers on LES+PEG was greater (P = 0.0221) compared to hair cortisol levels of steers on LES. This study indicated some changes in animal physiology in response to dietary supplements containing condensed tannins, but results were inconsistent and further studies are needed to better understand the potential benefits of tannins in reducing the effects of toxic alkaloids consumption. In the third study, behavioral and physiological responses of ewes that grazed either mid-stage hardwood silvopastures or open pasture (OP) were compared. The study site consists of 0.27-ha of black walnut (Juglans nigra; BSP) and honeylocust (Gleditsia triacanthos; HSP) silvopastures and open pasture treatments, each replicated three times. During the summers of 2020 and 2021, thirty-six Katahdin ewes were assigned to one of the treatments for a 6-week summer grazing trial. Ewe weights were recorded for two consecutive days at the beginning and end of the study and intravaginal temperatures were recorded for two consecutive days at every 3-week intervals. Trail cameras captured animal behavior. Blood was collected via jugular venipuncture. Hair grown during the trial was collected from the loin region. Blood and hair cortisol concentrations were determined by ELISA. Ewe ADG was greater in HSP compared to OP (P = 0.0456) but did not differ with BSP (P = 0.4686) across both years. Ewes on OP had hotter (P ≤ 0.0343) intravaginal temperatures than ewes on both silvopasture treatments between 1100h-1700h. Plasma cortisol level was lower in ewes on BSP compared to ewes on OP (P = 0.0400) but did not differ with ewes on HSP (P = 0.6954) across both years. Ewes that grazed OP had greater hair cortisol levels compared to ewes on silvopasture treatments both in 2020 and 2021 (P < 0.0001). In 2020, ewes on BSP spent about 20% more time grazing than ewes on OP (P = 0.0054) while in 2021 ewes on BSP spent about 36% more time grazing than ewes on HSP (P = 0.0014). Ewes on OP spent 400% more time standing than ewes on BSP (P < 0.0001) and 750% more time standing than ewes on HSP (P < 0.0001). Ewe on OP spent 20% less time lying down compared to ewes on BSP (P < 0.0001) and 33% less time lying down compared to ewes on HSP (P < 0.0001). Hair cortisol measures and intravaginal temperature sensors can be utilized as reliable and relatively non-invasive techniques for measuring heat stress response in livestock managed in extensive grazing systems. / Doctor of Philosophy / Heat stress compromises animal welfare and productivity, causing > $2B annual economic loss to producers in the U.S. In the southeastern U.S, heat stress in livestock is largely due both to an environmental condition and to the effect of fescue toxicosis caused by toxic alkaloids. Various management strategies to mitigate the effect of heat stress in livestock due to environmental conditions or due to the effect of tall fescue toxicosis are explored in this dissertation. In the first study, behavioral and physiological responses of heifers that grazed either toxic (WE) or novel (NE) endophyte-infected tall fescue was compared. Heifers that grazed WE tall fescue had lower gains, rough hair coat, higher hair cortisol level (stress measure), cooler extremity temperature, and hotter intravaginal temperature compared to heifers that grazed NE tall fescue. These results suggest that heat stress and other physiological changes in heifers grazing WE tall fescue could be mitigated by renovating pastures with NE tall fescue, a forage cultivar that does not impose any negative physiological effects on grazing animals. In the second study, we tested the effect of condensed tannins in reducing the severity of fescue toxicosis in steers. We fed sericea lespedeza pellets to steers in a study to test this effect. All steers were fed sericea pellets, but pellets for half (6) of the steers were treated with polyethylene glycol, which inactivates the condensed tannins in the sericea lespedeza. In our study, we found that the steers fed the sericea lespedeza had higher temperatures at their extremities (ears and tail), but lower rectal temperatures than the control steers. Interestingly, the steers fed the sericea lespedeza pellets also had slicker hair coats and lower levels of hair cortisol (indicating reduced stress) in the second year compared to the control steers. This study showed some potential of condensed tannins in reducing the effects of fescue toxicosis, but needs further study to better understand the potential benefits of tannins in reducing the post-ingestive effects of fescue toxicosis. In the third study, we compared behavioral and physiological (temperature, hair, and blood cortisol) responses of ewes that grazed either mid-stage hardwood silvopastures or open pastures (OP). Ewes on OP showed signs of heat stress with higher hair cortisol levels and hotter intravaginal temperatures during the daytime compared to ewes on silvopasture treatments. Ewes on OP spent 400% more time standing compared to ewes on BSP and 750% more time standing than ewes on HSP. Ewe on OP spent 20% less time lying down compared to ewes on BSP and 33% less time lying down compared to ewes on HSP. Ewes on silvopasture treatments spent 70% less time drinking water compared to ewes on OP. Trees within the silvopasture systems can alter the micro climatic condition thus creating a suitable environment for livestock. This can ultimately reduce stress and improve overall behavioral and physiological responses of livestock in silvopastures compared to open pastures.

Creeping bentgrass (Agrostis stolonifera L.) is a major low-cut cool-season turfgrass used worldwide. The objectives of this research were to: 1) to gain insight into the diurnal fluctuation of N metabolism and effects of cytokinin (CK) and nitrate; 2) to characterize the impacts of N and CK on creeping bentgrass under heat stress; 3) to investigate the simultaneous effects of CK and N on the antioxidant responses of heat stressed creeping bentgrass; and 4) to examine the expression pattern of the major heat shock proteins (HSPs) in creeping bentgrass during different heat stress periods, and then to study the influence of N on the expression pattern of HSPs. The transcript abundance of nitrate reductase (NR), nitrite reductase (NIR), plastidic glutamine synthetase (GS2), ferredoxin-dependent glutamate synthase (Fd-GOGAT), and glutamate dehydrogenase (GDH) and N metabolites in shoots were monitored during the day/night cycle (14/8 h). All the measured parameters exhibited clear diurnal changes, except GS2 expression and total protein. Both NR expression and nitrate content in shoots showed a peak after 8.5 h in dark, indicating a coordinated oscillation. Nitrate nutrition increased diurnal variation of nitrate content compared to control and CKHowever, CK shifted the diurnal in vivo NR activity pattern during this period. Grass grown at high N had better turf quality (TQ), higher Fv/Fm, normalized difference vegetation index (NDVI), and chlorophyll concentration at both 15 d and 28 d of heat stress than at low N, except for TQ at 15 d. Shoot NO3-, NH4+, and amino acids increased due to the high N treatment, but not water soluble proteins. High N also induced maximum shoot nitrate reductase activity (NRmax) at 1 d. CK increased NDVI at 15 d and Fv/Fm at 28 d. In addition, grass under 100 µM CK had greatest NRmax at both 1 d and 28 d. Under high N with 100 µM CK, root tZR and iPA were 160% and 97% higher than under low N without CK, respectively. Higher O2- production, H2O2 concentration, and higher malonydialdehyde (MDA) content in roots were observed in grass grown at high N. The activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), and guaiacol peroxidase (POD) in roots were enhanced by high N at 19, 22, and 24% levels, respectively, relative to low N. Twenty-eight days of heat stress resulted in either the development of new isoforms or enhanced isoform intensities of SOD, APX, and POD in roots compared to the grass responses prior to heat stress. However, no apparent differences were observed among treatments. No CK effects on these antioxidant parameters were found in this experiment. At week seven, grass at medium N had better TQ, NDVI, and Fv/Fm accompanied by lower shoot electrolyte leakage (ShEL) and higher root viability (RV), suggesting better heat resistance. All the investigated HSPs (HSP101, HSP90, HSP70, and sHSPs) were up-regulated by heat stress. Their expression patterns indicated cooperation between different HSPs and that their roles in creeping bentgrass thermotolerance were affected by N level. / Ph. D.

Many factors influence the efficiency of muscle growth including genetics, nutrition, and environment. The neonatal period is characterized as a time of rapid growth. Growth rate is reduced during neonatal nutrient restriction possibly due to altered satellite cell activity which can permanently alter growth potential. Therefore, optimal nutrition is important for maximizing the growth potential of the animal. Heat stress leads to changes in digestion and metabolism, thus alters nutrient availability to muscle. Heat stress is a prevalent problem in the agriculture industry resulting in great economic losses due to reduced growth, fertility, and increased morbidity. The use of functional feed additives is a potential strategy to mitigate these negative effects. The objective of this dissertation was to investigate nutritional strategies to improve growth in pigs during key malleable periods. Three nutritional studies were conducted to discern the optimal inclusion levels of calcium phosphate, energy, and protein in the diet to maximize neonatal muscle growth. Adequate dietary calcium phosphate was most efficient for satellite cell function which may be mediated by micro-RNA. Differentiation promoting miR-206 and correspondingly the fusion rate was highest in adequate calcium phosphate diets. Excess protein diets enhanced body and muscle growth, while deficient protein was detrimental to growth. Dietary protein treatments altered energy metabolism genes, and genes regulating protein degradation were upregulated in deficient protein diets. Dietary energy levels did not influence body weight, however feed efficiency improved with energy balance. Excess energy diets had the lowest fusion rates and the lowest differentiation promoting miR-1 expression. These data suggest that nutrient inclusion levels are important for satellite cell function and may mediate satellite cell activity through the expression of micro-RNAs. The final study sought to discern the ability of supplementation of an artificial high-intensity sweetener and capsicum oleoresin to mitigate the negative effects of heat stress on pig performance. Heat stress leads to increased body temperature and respiration and was detrimental to metabolic flexibility. Supplementation helped improve feed efficiency and maintain metabolic flexibility. These data indicate that supplementation may be an efficient strategy to mitigate heat stress. / Doctor of Philosophy / Muscle is an important tissue to consider when optimizing growing conditions in feed animals due to its function as a consumer good. Many factors influence the efficiency of muscle growth including genetics, nutrition, and environment. Fractional growth rates are highest during the neonatal period and animals require adequate nutrients to facilitate this growth. Nutrient restriction reduces growth rate and can lead to permanent changes the animals' body size and composition later in life. Therefore, optimal nutrition is important for maximizing the growth potential of the animal. While the nutrients in feed can be controlled to improve growth, other factors are more difficult to regulate. Heat stress is a prevalent problem in the agriculture industry resulting in great economic losses due to reduced growth, fertility, and increased morbidity. The use of functional feed additives is a potential strategy to alleviate these negative effects. The objective of this dissertation was to investigate nutritional strategies to improve growth in pigs during key malleable periods. Three nutritional studies were conducted to determine the optimal inclusion levels of calcium phosphate, energy, and protein in the diet to maximize neonatal muscle growth. Satellite cells are muscle-specific stem cells that help facilitate the growth of muscle. Altering the ability of satellite cells to proliferate and fuse impairs the ability of muscle to grow and repair. Adequate dietary calcium phosphate was most efficient for satellite cell function. Excess protein diets enhanced body and muscle growth, while deficient protein was detrimental to growth. Dietary protein treatments altered energy metabolism genes, and genes regulating protein degradation were upregulated in deficient protein diets. Dietary energy levels did not influence body weight, however, feed efficiency improved with energy balance. Satellite cells from excess energy diets had the lowest fusion rates. These data suggest that nutrient inclusion levels are important for satellite cell function and growth. The final study sought to discern the ability of the supplementation of an artificial high-intensity sweetener and capsicum oleoresin to mitigate the negative effects of heat stress on pig performance. Heat stress leads to increased body temperature and respiration and was detrimental to metabolic flexibility. Supplementation helped improve feed efficiency and maintain metabolic flexibility. These data indicate that supplementation may be an efficient strategy to mitigate heat stress.

As climate change exacerbates heat stress during the summer season, it becomes increasingly critical to develop effective strategies to safeguard the productivity of tomato plants (Solanum Lycopersicon L.). This research delves into the tools and techniques aimed at enhancing the cultivation of summer tomatoes in the coastal region of Virginia. The study explores the optimization of transplant dates, the implementation of reflective mulches, and the application of kaolin clay particle films. Field trials spanning two seasons were carried out, comparing different planting dates in May, June, and July, as well as the use of reflective, black, and white plastic mulches, both with and without foliar kaolin sprays. The findings of this study underscore the impact of transplanting tomatoes in May, demonstrating a substantial increase in yields when compared to transplanting in June and July. Reflective mulches enhanced plant height and fruit production relative to the conventional black plastic mulch. The combination of kaolin clay sprays with standard black mulch, resulting in yield increases of over 35%, rivaling the outcomes achieved with reflective and white mulch treatments. The application of kaolin did not significantly affect leaf-level physiological processes. These results highlight the significant potential of strategic early planting and the adoption of emerging heat mitigation technologies, such as kaolin clay films, in sustaining and enhancing the productivity of summer tomatoes. This becomes particularly relevant as growing conditions continue to evolve due to rising temperatures and the increasing extremity of weather events resulting from climate change. / Master of Science in Life Sciences / With the challenge of hotter summers due to climate change, finding effective ways to grow tomatoes is more crucial than ever. In our two-season study in Virginia's coastal region, we experimented with various methods to improve tomato growth in these warmer conditions. What we discovered was quite promising. Planting tomatoes in early May resulted in significantly better yields than later planting times. Using reflective mulch was beneficial too; it helped the plants grow taller and produce more fruit compared to traditional black mulch. However, the most impressive result came from combining kaolin clay spray with black mulch. This approach led to a matching of the performance of black plastic plus the combination of kaolin clay against reflective and white mulches. It's interesting to note that the kaolin spray didn't alter the basic functioning of the plants at the leaf level. These findings are encouraging. They suggest that early planting and innovative approaches like kaolin clay sprays can effectively boost tomato production, even as we contend with rising temperatures and evolving climate patterns. Embracing these strategies could be key to successful tomato farming in an era of climate change

This study was conducted to explore the feasibility of using sleeves, along with both physiological and perceptual measurements, to assess the thermal comfort and heat strain in chemical protective clothing wear tests. The effect of body sites, i.e. the arms and the chest, and the effect of a Tyvek® coverall on skin temperature and sweat amount were investigated as well. Ten male subjects were selected from college students. Each subject was assigned to wear a garment of either T-shirt and pants or a changeable left-sleeved Tyvek® coverall with or without an experimental sleeve on the left arm. Three experimental sleeves were of the same style, but made of three different fabrics: Tyvek®, Pro/Shield I®, and Pro/Shield II®. Each subject wore an assigned garment and pedaled on a cycle ergometer in an environmentally-controlled room. Skin temperature, sweat amount, and subjective comfort evaluations were recorded and later analyzed by repeated-measures ANOVA. Results showed there is a feasibility in using a sleeve with a T-shirt/pants standard garment for assessing thermal comfort in chemical protective garment wear tests. The T-shirt/pants standard garment yielded more consistent and reliable results than did the Tyvek®-coverall standard garment. Under the same conditions, there were no significant differences in skin temperature and sweat amount among the left and right upper arms and the chest. The Tyvek® sleeve in this study impeded the transfer of heat by the greatest amount, followed by the Pro/Shield II® sleeve and the Pro/Shield I® sleeve, respectively. / Master of Science

Climate change will increase the intensity and duration of heat waves in Sweden. Vulnerable communities are especially affected by the effects of heat waves and since children rely on adults to provide comfort, children are particularly affected by heat wave impacts. The aim of this study was to characterize how preschool children and preschool activities were affected by heat exposure based on the perspectives of preschool educators. Six group interviews were conducted with twelve preschool educators in Linköping and Norrköping and the data was analyzed using reflexive thematic analysis. The results indicate that the lack of shaded areas in the preschool yards causes considerable negative impacts on the health of preschool children and obstructs suitable preschool activities. Future research should explore the possibilities of connecting urban planners with preschool educators in the planning phase of preschools in order to utilize their experiences on how to mitigate the effects of heat waves on preschools. / BRIGHT