Exposure to thermal stress can negatively impact an animals' overall welfare, resulting in decreased body condition, lower reproductive success, and in severe cases, mortality. The swine industry has prioritized efficient production and as a result has gained rapid improvements in lean growth and increase litter sizes. Unfortunately, modern swine are unable to cope with the negative effects of heat stress. Thus, it is crucial to understand the preferred temperature of swine to create recommendations on when to initiate mitigation strategies to combat the negative effects of thermal stress. However, several different factors contribute to an animals' thermal comfort and thermal preference will differ based on age, reproductive stage, social context, early life thermal stress, and behavior. Thus, making it exceptionally difficult to classify an animal's thermal comfort zone. These studies aim to highlight how those factors influence thermal comfort in pigs and help guide recommendation polices for housing pigs in their preferred temperatures.<br>

In recent years, U.S. swine producers have received pressure from consumers to reduce antibiotic usage. With the increased consumer pressure, pork producers have sought out other technologies, including feed additives, to reduce antibiotic usage in commercial pork production. Therefore, the objective of Chapter 2 was to determine whether supplementing L-glutamine at cost-effective levels can replace dietary antibiotics to improve pig welfare and productivity following weaning and transport. Based on previous research, we hypothesized that withholding dietary antibiotics would negatively affect pigs while diet supplementation with 0.20% L-glutamine (GLN) would have similar effects on pig performance and health as antibiotics. Mixed sex pigs (N = 480; 5.62 ± 0.06 kg BW) were weaned (18.4 ± 0.2d of age) and transported for 12 h in central Indiana, for two replicates, during the summer of 2016 and the spring of 2017. Pigs were blocked by BW and allotted to 1 of 3 dietary treatments [n = 10 pens/dietary treatment/replicate (8 pigs/pen)]; antibiotics [A; chlortetracycline (441 ppm) + tiamulin (38.6 ppm)], no antibiotics (NA), or GLN fed for14 d. On d 15 to 34, pigs were provided common antibiotic free diets in two phases. Data were analyzed using PROC MIXED in SAS 9.4. Day 14 BW and d 0 to 14 ADG weregreater (P = 0.01) for A (5.6% and 18.5%, respectively) and GLN pigs (3.8% and 11.4%, respectively) compared to NA pigs, with no differences between A and GLN pigs. Day 0 to 14 ADFI increased for A (P < 0.04; 9.3%) compared to NA pigs; however, no differences were detectedcomparing GLN to A and NA pigs. Once dietary treatments ceased, no differences (P > 0.05) in growth performance amongdietary treatments were detected. On d 13, plasma tumor necrosis factor alpha (TNF-α) was reduced (P = 0.02) in A (36.7 ± 6.9 pg/ml) and GLN pigs (40.9 ± 6.9 pg/ml) versus NA pigs (63.2 ± 6.9 pg/ml). Aggressive behavior tended to be reduced overall (P = 0.09; 26.4%) in GLN compared to A pigs, but no differences were observed between A andGLN versus NA pigs. Huddling, active, and eating/drinking behaviors were increased overall (P < 0.02; 179, 37, and 29%, respectively) in the spring replicate compared to the summer replicate. A subset of pigs from Chapter 2 were utilized, in Chapter 3, toevaluate the dietary treatment effects on intestinal morphology and gene expression. On d 33, mast cells/mm2were increased (P= 0.05) in GLN and NA pigs vs. A pigs (22.2% and 19.7%, respectively). On d 33, villus height:crypt depth tended to be increased(P= 0.07; 7.0%) in GLN and A pigs vs. NA pigs.On d 33, glucagon-like peptide 2 (GLP-2)mRNA abundance was decreased (P= 0.01; 50.3%) in GLN and NA pigs vs. A pigs.Crypt depth was increased (P= 0.01; 16.2%) and villus height:crypt depthratiowas reduced (P= 0.01; 9.6%)during the spring replicate compared to the summer replicate on d 33. On d 13, TNF-α and occludin mRNA abundance wereincreased (P≤0.04; 45.9%and 106.5%, respectively)andzonula occludens-1(ZO-1)mRNA abundance tended to be increased (P= 0.10; 19.2%) in the spring replicate compared to the summer replicate. Previous research and the results of Chapter 2 indicates that supplementing nursery diets with 0.20% GLN provides similar growth and health benefits as dietary antibiotics, but it is unknown whether greater inclusion levels will provide additional benefits. Therefore, the objectiveof Chapter 4 was to evaluate the impact of replacing dietary antibiotics with increasing levels ofGLNon growth performance, health status, and production costs in pigs following weaning and transport. We hypothesized that diet supplementation with 0.20% to 1.00% GLNwould incrementally improvepig health and productivity compared to dietary antibiotics. Mixed sex pigs (N = 308; 5.64 ± 0.06 kg BW) were weaned (19.1 ± 0.2 d of age) and transported in central Indiana during the autumn of 2017. Pigs were blocked by BW and allotted to 1 of 7 dietary treatments (n = 8 pens/dietary treatment); A[chlortetracycline (441 ppm)+ tiamulin (38.6 ppm)], NA, 0.20% GLN, 0.40% GLN, 0.60% GLN, 0.80% GLN, or 1.00% GLNfed for 14 d. On d 15 to 35, pigs were provided NA diets in two phases. Data were analyzed using PROC MIXED in SAS 9.4. Overall, ADG (P= 0.04; 6.4%) and ADFI (P= 0.04; 6.9%) were reduced in NA pigs vs. 0.40% GLN or A pigs. Increasing GLN in the diet tended to increase (linear;P= 0.10) ADG. Overall, increasing GLN in the diet tended to increase (linear; P= 0.08) d 35 BW. Day 35 BW was greater (P= 0.01) in 0.80%GLN and A pigs compared to NA, 0.20% GLN, and 0.60% GLN pigs, but no BW differences were detected between 0.80% GLN and A and 0.40% GLN and 1.00% GLN pigs. In addition, d 35 BW was greater (P= 0.01) for 0.40% GLN and 1.00% GLN compared to 0.20% GLN. Overall income over feed and therapeutic injectable antibiotics cost for enteric and unthrifty challenges was greater (P= 0.02) in 0.80% GLN pigs compared to NA, 0.20% GLN, and 0.60% GLN pigs, but no income over feed and therapeutic injectable antibiotics cost for enteric and unthrifty challenges differences were detected between 0.80% GLN pigs and 0.40% GLN, 1.00% GLN, and A pigs. Health challenges in swine herds negatively impact swine growth rate and performance. Therefore,utilizing the pigs from Chapter 2, the study objective for Chapter 5 was to quantifythe impact of differences in rearing conditions through post hoc analysis on growth performance, tissue accretion rates, and production economics in pigs during different replicates(summer or spring). We hypothesized that pigs reared under health challenged conditions would have decreased growth performance and tissue accretion rates resulting in increased production costs compared to pigs reared with less health challenges. Data were analyzed using PROC MIXED and PROC NLMIXED in SAS 9.4. Therapeutic injectable antibiotics cost was reduced(P= 0.01; 246.7%) in the spring replicate compared to the summer replicate. Income over feed and therapeutic injectable antibiotics cost was greater (P= 0.01; 23.1%; $16.62/pig) in the spring replicate compared to the summer replicate.Predicted ADG was greater (P≤ 0.05) in spring replicate barrows compared to thesummer replicate barrows during the ranges of 22 to 38 and 119 to 177 days of age, respectively. Spring replicate gilts had greater ADG (P≤ 0.05) compared to summer replicate gilts during the ranges of 22 to 47 and 112 to 177 days of age, respectively. The maximum predicted empty body protein accretion rate for the summer replicate gilts and the spring replicate gilts is 145 and 156 g/d, respectively. In conclusion, GLN supplementation improved pig performance and health after weaning and transport similarly to A across studies and GLN shows promise as an antibiotic alternativewith 0.40% GLN appearing to be the optimal level. Health challenges in pigs can have profound negative impacts on tissue accretion ratesand key economic drivers for pork producers such as poorer feed efficiency and reduced hot carcass weight. The adverse health effects resulting in reduced growth performance, increased production costs($16.62/pig), and negatively impact producer profitability.<p> </p>

Heat stress (HS) is one of the consequential important problems facing the swine industry. The negative effects of HS include reduced growth performance, reproductive efficiency, and carcass quality as well as increased morbidity and mortality. Although, the swine industry has developed several abatement strategies (i.e., fans, cooling pads, sprinklers, etc.), these approaches may be ineffective in the future as global temperatures continue to rise and the frequency of more severe heat waves increases in regions where animal agriculture is prevalent. These extreme heat events put pigs (especially those approaching market weight) at risk for acute hyperthermia that can lead to death unless body temperature is rapidly returned to euthermia and thermoregulatory function is restored.Therefore, evaluating mitigation strategies to promote recovery from acute hyperthermia is of utmost importance for improving pigs’ health and well-being and ensuring profitability and food security. In four experiments, the existence of microclimates in grow-finish barns during late summer was ascertained and a rapid cooling technique using cold water dousing and feed removal to promote recovery from acute hyperthermia in pigs was evaluated. In the first study, it was determined that microclimates exist in grow-finish barns and that pigs raised in pens that were not located directly below air inlets and ventilation fans had greater body temperature and reduced feed efficiency despite similarities in the in-barn ambient temperature and relative humidity. These data exemplifythe importance of adequate ventilation systems in swine barns and the impact of microclimates on pigs’ health and productivity during warm summer months. In the second study, grow-finish pigs that did not have feed access were exposed to acute HS and then rapidly or gradually cooled. Following the acute HS and recovery phase, all pigs were maintained under thermoneutral conditions and then euthanized over three days to determine the temporal effects of the cooling treatment on body temperature and intestinal integrity. The results showed that rapid cooling following acute hyperthermia in pigswas effective in returning body temperature to euthermia more rapidly compared to gradual cooling and rapid cooling prevented further intestinal damage. Based on these results, it was hypothesized that feed removal may have played a role in the effectiveness of rapid cooling. Therefore, a third experiment was conducted in which grow-finish pigs with or without access to feed were exposed to an acute HS challenge and then rapidly cooled. This study concluded that feed access was a determinant factor in the cooling outcome, as the gastrointestinal temperature returned to euthermia during the rapid cooling period more rapidly when feed was removed. Finally, a fourth study was conducted to evaluate the effects of feed removal in the absence of rapid cooling on the systemic inflammatory response and short-term growth performance of grow-finish pigs. However, it was determined that feed removal alone did not reduce the inflammatory response as expected. Overall, these studies demonstrate the risk forgrow-finish pigs during summer heat events and the potential use of rapid cooling in combination with feed removal for promoting recovery from acute hyperthermia in pigs.

This study was undertaken to compare the MIC (minimum inhibitory concentration) and MPC (mutant prevention concentration) values for oxytetracycline and florfenicol against strains of Pasteurella multocida isolated from cattle and pigs, and for enrofloxacin against strains of Salmonella Typhimurium isolated from horses. Isolates of P. multocida from cattle and pigs, and S. Typhimurium from horses were obtained from specimens or isolates from contributing laboratories. All the equine isolates and 50% of the cattle and pig isolates were from clinically sick animals. All isolates were tested in duplicate with both the MIC and the MPC methods. The MIC method used was the standardized microdilution method performed in microtitre plates. The MPC method used was according to the method described by Blondeau. This method was modified, to make use of smaller plates and lower volumes of antimicrobials, but retaining a final bacterial concentration of 109 colony-forming units per ml. The antimicrobials were dissolved as described in the certificates of analyses. Enrofloxacin and oxytetracycline were dissolved in water, and florfenicol was dissolved in alcohol. For the MPC method, an additional control was added to one quadrant of a four-quadrant 90mm plate/petri dish. The antimicrobials were tested as individual antimicrobials and not as combinations. Both the MIC and MPC methods included ATCC (American Type Culture Collection) strains as control organisms and were evaluated according to the guidelines of the CLSI (Clinical and Laboratory Standards Institute). The MIC50 values for enrofloxacin against Salmonella Typhimurium isolates from horses was 0.25 ìg/ml and the MPC50 values 0.5 ìg/ml. A comparative reference range was not available as enrofloxacin is not registered in South Africa for use in horses, and is used extra-labelly. The results for florfenicol against P. multocida yielded an MIC50 value of 0.5 ìg/ml and an MPC50 value of <2 ìg/ml. The close relationship of these two concentrations is an indication of the effectiveness of florfenicol when used against P. multocida. The PD/PK data with a value of 141.78 for AUC/MIC provided additional support for the efficacy of florfenicol against P. multocida. The PD/PK value of >125, is an effective parameter for treatment of Gram-negative bacteria. The corresponding results for oxytetracycline were above the MIC value but fell within the mutant selection window. The results point to the fact that the use of oxytetracycline against P. multocida may not be effective in preventing the appearance of first step mutant strains when used at current recommended dosages. The PK/PD data, using AUC/MIC, yielded a value of 56. Some of the isolates (55.17%) had an MPC value of 16 ìg/ml. Whereas the MIC method is used routinely in diagnostic laboratories, the MPC method can be employed to generate data that can be applied where antimicrobial treatment of certain bacteria is problematic and standard treatment may lead to the development of resistance. Data obtained from such studies will enable manufacturers of antimicrobial drugs to adapt antimicrobial therapy where practical and feasible to prevent the development of first step mutants. / Dissertation (MSc)--University of Pretoria, 2012. / Veterinary Tropical Diseases / unrestricted

Porcine Reproductive and Respiratory Syndrome (PRRS) is a controlled disease in South Africa. This disease is caused by an Arterivirus and occurs commonly in Europe (European serotype) and in the United States of America (American serotype); therefore PRRS is not a trade sensitive disease. However, the disease has severe economic implications for the producer and the local pork industry and the decision was made by the Department of Agriculture, Fisheries and Forestry in association with the South African Pork Producers’ Organization (SAPPO) to eradicate the disease when the first outbreak occurred in 2004 in the Western Cape. Severe disease leading to acute mortalities and almost 100% mortality and morbidity rate in a few pig units in the Jacobsdal area (Kuilsrivier district) in the Cape Town peninsula, alarmed local veterinary consultants during the autumn of 2004. A first diagnosis of Salmonella choleraesuis was confirmed at the Provincial Veterinary Laboratory in Stellenbosch. Antibiotic treatment did not resolve the clinical picture. Sows still aborted and died and young pigs still died from acute respiratory distress. The syndrome was similar to “blue ear disease” because of severe cyanosis visible on the extremities of affected pigs. The first suspected diagnosis of Porcine Reproductive and Respiratory Syndrome virus (PRRSV) was made on post mortem examination on 10 June 2004 and was confirmed on 17 June 2004 with positive ELISA (Idexx Herdchek PRRSV Ab test kit 2XR) results. A stamping out procedure immediately followed through slaughtering of all affected pigs showing clinical signs of PRRSV infection. Pigs in close proximity with possible contact and infection risk were also slaughtered. The movement of pigs was only allowed under Red Cross permit and all pig auctions were stopped. A local and countrywide serological survey was implemented immediately. The results of this survey luckily showed that the outbreak was limited to a few districts in the Western Cape. The probable source of infection is suspected to be uncooked swill originating from the Cape Town Harbour or the Cape Town International Airport, which was fed to pigs. The PRRSV responsible for the outbreak was confirmed on 5 July 2004 as the American serotype by RT-PCR test done at Lelystad, Netherlands. The National Department of Agriculture (NDA)* agreed to compensate pig owners for slaughtered pigs. This decision was further made possible by funding from SAPPO to protect the rest of the commercial pig herd in South Africa to ensure food safety and security. A total of 32 pig units were affected by PRRS of which only one was a commercial unit. All affected pigs were slaughtered by the end of August 2004. Units were cleaned and disinfected by the staffs of the Boland and Swartland State veterinary departments with approved disinfectants which is effective against PRRSV. Cleaned units had to stay empty of pigs for at least 8 weeks after disinfection was completed. Restocking was only allowed from known PRRS-free pig suppliers and regular monitoring was implemented of all previously infected sites and units in high risk areas. On-going serological monitoring revealed no more positive cases since May 2005. It seems that the stamping out procedure and a temporary ban on movement and auctions of live pigs played a primary role in eradication of the PRRSV outbreak in South Africa in 2004. * The name of the NDA has been changed to the National Department of Agriculture, Forestry and Fisheries (DAFF) in 2009, but because the NDA was the applicable name when the PRRS outbreak occurred, NDA will be used in this document. / Dissertation (MMedVet)--University of Pretoria, 2010. / Production Animal Studies / unrestricted

The purpose of this study was to examine the effects of changes in magnitude of negative reinforcement on multiple schedules with the guinea pigs. In both schedule components, the first response (lever press) after an average of 10 seconds was reinforced. In the constant component of this schedule the reinforcement magnitude (time-off from electric foot shock) was always 15 seconds; whereas, in the manipulated component the magnitude changed in the following sequence: 15, 7.5, 15, 30, and 15 seconds. All subjects showed a gradual decrease in response rate across baseline conditions. When behavioral effects were evaluated relative to this changing baseline, five of six subjects demonstrated that as the reinforcement magnitude decreased in one component, the response rates in both components decreased (negative induction). Likewise, when reinforcement magnitude increased in one component, all subjects showed behavioral induction. Specifically, three subjects showed increases in response rate in both components (positive induction), while two subjects showed decreases in response rate in v both components (negative induction). This research extends the generality of the behavioral induction phenomena on multiple schedules to in elude negative reinforcement with the guinea pig as a function of changes in reinforcement magnitude

Seminal plasma (SP) is the microenvironment of spermatozoa whose composition reflects semen quality and constitutes an excellent source for detecting non-invasive biomarkers. This study characterizes good vs. poor quality semen using seminal extracellular vesicles coupled proteins and miRNA. Fresh boar semen samples were screened, centrifuged, and SP supernatants were collected for near-infrared spectroscopy (NIRS) analysis. EVs were extracted from SP (SP-EVs), characterized, and those of extremely poor or good sperm quality groups were subjected to proteomics and small RNA sequencing. Significant differences were set for P

This study was done by administering household surveys to 50% of the families in the three communities. Families were selected through stratified random sampling. This allowed us to determine how much families are exploiting species that have a significant level of production as well as whether they use them for a commercial activity or subsistence. With regard to cows, 60.40 ± 4.72% of families use them. Each family has an average of 1.68 ± 0.21 cows. Productive cows make up 36.9% of the above percentage, which is a majority. The measured rate of production was 6.48 ± 0.25 L/cow/day. Overall, 40.16 ± 3.17% of production was used for household consumption while the rest was sold. These parameters as well as the sale of live animals helped San Nicolas have an annual income of 735 US dollars, which shows that this community relies more on commercial activity. On the other hand, San Clemente and San Francisco had annual incomes of 367 and 279 US dollars respectively. This shows that these communities focus more on familial subsistence. Of the major species, sheep are the least exploited with 54.80 ± 8.74% of families using them. The first lambing occurs at 17.79 ± 0.48 months. Newborns are weaned at 5.57 ± 0.11 months by only 27.27 ± 4.47% of families. Of the weaned newborns, 60.69 ± 5.13% are kept and the rest are sold. Every 10.46 ± 0.47 months, 77.96% of the wool produced is sold. Generally, the sheep are sol d at 22.84 ± 1.75 months of age. This generates an average annual income of 40.85 ± 19.26 US dollars, which indicates that this activity is focused on familial subsistence. Swine production is the most common form of animal production. Pigs are exploited by 81.86 ± 7.17% of families with each family having an average of 2.11 ± 0.16 animals. A sow’s first delivery occurs at 16.48 ± 0.48 months and their productive life comes after reproducing 1.98 ± 0.15 times. Each litter has 5.72 ± 0.19 offspring with a post-weaning mortality rate of 28.99 ± 4.82%. Offspring are weaned at 2.90 ± 0.12 months. Overall, 65.13% of the weaned offspring are kept and the rest are sold. Annual revenue from pig production is 63.2 ± 22.46 US dollars which indicates it is used for familial subsistence, acting as a safeguard against economic emergencies at times. Of the minor species, the guinea pig is the most exploited. It is used by 86.11 ± 3.65% of families with each family having an average of 12.04 ± 1.31 guinea pigs. The mothers have an average of 2.44 ± 0.06 offspring per litter with a weaning rate of 75.81 ± 4.33%. Overall, 86.91% of production is used for family consumption and the rest is sold. The annual income generated by this activity is 6.24 ± 0.51 US dollars which indicates that this is an activity dedicated to providing food for the family. Rabbits are used by 49.42 ± 5.23% of families, each having an average of 4.03 ± 0.64 animals. There is an average of 6.57 ± 0.29 newborns per litter with a weaning rate of 41.16 ± 5.20%. Overall, 80.18 ± 4.16% of production is used for family consumption. This activity is similar to guinea pig production seeing as the annual income it generates is only 12.80 ± 1.10 US dollars. Chickens are exploited by 77.33 ± 4.39% of families with each family having an average of 5.88 ± 0.60 animals. Broiler chickens make up 48.22% of the poultry population with the rest being made up of native and field hens. Overall, 68.96% of broiler chickens are used for family consumption while 89.31 ± 3.27% of hens are used for family consumption. The annual income from this activity is 40.13 ± 19.24 US dollars. This makes it appear to have a slight tendency toward commercial use. We conclude that the three communities have different levels of animal exploitation. San Nicolas was the most successful of the three, partially using their livestock production for commercial purposes. San Clemente used part of theirs for commercial purposes as well, but on a lower scale. San Francisco, on the other hand, focuses their livestock production solely on familial subsistence. We recommend that a study be conducted regarding all points involved in the feasibility of production projects in these communities, especially in regard to the organization in each community. This will help improve production levels and make way for a change from a subsistence based economy to a more commercially based economy, ultimately improving the social and nutritional levels of these families.

Policy makers have long recognized the importance of considering past experience, history, and the use of Analogical reasoning when making policy decisions. When elite political actors face foreign policy crises, they often use their past experience, refer to history, and use Analogical reasoning to help them frame their decisions. In the case of the ill-fated invasion of Cuba at the Bay of Pigs, the use of Analogical reasoning revolving around past covert successes may have created an environment for faulty foreign policy decision-making. Former members of the Office of Strategic Services (OSS) filled the ranks of the Central Intelligence Agency (CIA) and held key positions within the Eisenhower and Kennedy administrations. OSS success with guerrilla warfare, sabotage, and intelligence gathering during World War II, coupled with early CIA covert successes (specifically in Guatemala), may have led President Kennedy to make the wrong policy decisions with regard to dealing with Fidel Castro and Cuba. This research explores the use of Analogical reasoning during the decision-making process by way of process-tracing. Process-tracing attempts to identify the intervening processes between an independent variable (or variables) and the outcome of the dependent variable. We look at six critical junctures and compare how Groupthink, the Bureaucratic Politics Model, and Analogical reasoning approaches help explain any causal mechanisms. The findings suggest that Analogical reasoning may have played a more significant role in President Kennedy's final decision to invade Cuba than previously thought. The findings further suggest that by using the Analogical reasoning approach, our understanding of President Kennedy's foreign policy in Cuba is enhanced when compared to the Groupthink and Bureaucratic Politics Model approaches emphasized in past research.

<p> As the effects of climate change become more evident, the development of effective strategies for improving livestock climatic adaptation and the long-term sustainability of animal food production have become key priorities around the world, including in the US. Together with nutrition, infrastructure, and management practices, genetically improving animals is an effective and lasting alternative to simultaneously improve productive efficiency and climatic adaptation of animals. Genetic improvement requires basic understanding of the genomic architecture of the indicator traits of interest and the availability of large-scale datasets. Understanding the role of evolution and selection (both natural and artificial) on shaping animal genomes is of paramount importance for the optimization of breeding programs and conservation of genetic resources. In addition, properly quantifying environmental stress and individual animal responses to thermal stress are still important challenges in breeding programs. Thus, the identification of optimal statistical methods and traits that better capture key biological mechanisms involved in the heat stress response has the potential to enable more accurate selection for thermal tolerant individuals. Therefore, this thesis aimed to investigate complementary topics related to thermal tolerance in livestock species based on genomic information. A total of 946 genotypes from 34 cattle breeds, as well as Datong yak (<em>Bos grunniens</em>) and Bali (<em>Bos javanicus</em>) populations, adapted to divergent climatic conditions, were used to investigate the genetic diversity and unravel genomic regions potentially under selection for thermal tolerance, with a focus on Chinese local cattle breeds and yak. Different signature of selection analyses and a comprehensive description of genetic diversity in 32 worldwide cattle and Datong yak populations was presented. Moderate genetic diversity was observed within each Chinese cattle population. However, these results highlighted the need to adopt strategies to avoid further reduction in the genetic diversity of these populations. Several candidate genes were identified as potentially under selection for thermal tolerance, and important biological pathways, molecular functions, and cellular components were identified, which contribute to our understanding of the genetic background of thermal tolerance in <em>Bos</em> species. Secondly, 8,992 genotyped individuals were used to provide a comprehensive description of genotype-by-environment interaction effects, defining optimal environmental variables based on public weather station data, and critical periods to evaluate heat tolerance for various reproduction, growth, and body composition traits in US Large White pigs. The period of 30 days before the measurement date was suggested to analyze genotype-by-environment interaction for off-test weight, muscle depth, and backfat thickness. While for number of piglets weaned and weaning weight, the suggested period ranged from the last trimester of gestation until weaning. This same population was used to access the genomic predictive ability of heat tolerance based on routinely-measured traits and explore candidate regions involved in the biological mechanisms that underlie heat stress response in pigs. Genotype-by-environment interaction was identified for most of the traits evaluated, and moderate (>0.36 ± 0.05) breeding values prediction accuracy were achieved using genomic information. Lastly, various behavioral, anatomical, and physiological indicators of heat stress were measured in a population of 1,645 multiparous Large White x Landrace lactating sows. This dataset was used to identify the best statistical models and estimate genomic-based genetic parameters for 23 indicators of heat stress, including automatically-measured vaginal temperature, skin surface temperatures, respiration efficiency, respiration rate, panting score, body condition scores, hair density, body size, and ear measurements. All the traits evaluated are heritable, with heritability estimates ranging from 0.04 ± 0.01 to 0.40 ± 0.09. The genetic correlations among these traits ranged from -0.49 (between repeated records of vaginal temperature measured at 0800 hours and caliper body condition score) to 1.0 (between repeated records of vaginal temperature measured at 0800 hours and single record of vaginal temperature measured at 0800 hours; and between repeated records of vaginal temperature measured at 1200 hours and single record of vaginal temperature measured at 1200 hours). These findings indicate that genetic progress for thermotolerance in pigs can be achieved through direct indicators of heat stress in selection schemes. However, special attention is needed due to complex relationship between these traits as evidenced by their genetic correlations. In conclusion, this thesis provides important information to be used when designing breeding strategies for improving thermal tolerance in cattle and pigs, important genomic regions and metabolic pathways that are important for understanding the biological mechanism regulating thermal tolerance, as well as future directions for investigations in the area of livestock climatic adaptation.</p>