Pigs exposed to chronic intrauterine hyperthermia (gHS) experience greater fat deposition during life and yield carcasses with greater fat:lean content at slaughter compared to pigs gestated under thermoneutral conditions (gTN). The objectives of this study were to 1) determine whether gHS impacts the lactational performance of affected gilts (F1 generation), and 2) determine whether these effects of gHS are also evident in the next generation (F2 generation). Twenty-four gilts were bred and exposed to thermoneutral or heat stressed conditions for the entirety of gestation, and F1 female offspring were retained. At puberty, gHS and gTN gilts were bred to farrow in either spring (March / April) or summer (July / August). Colostrum and milk samples were collected at farrowing and on d 7, 14, and 21 of lactation. At weaning, four offspring (two male, two female) were retained and grown to market weight in mixed-pens under identical management conditions. Carcass characteristics were analyzed at slaughter. Milk nutrient analysis indicated that gHS gilts produced less lactose, and tended to produce greater protein, than did gTN gilts. There was no difference in the growth rate of F2 offspring, but pigs born of gHS dams did have a tendency for greater backfat thickness. The patterns of altered milk nutrient content observed in F1 gilts reflects a metabolic profile consistent with previous gHS research, and the greater backfat of F2 pigs at slaughter indicates the adipose-promoting effects of gHS may be diluted, but still evident, in the second generation. / Master of Science

Prolonged exposure to high ambient temperature without cooling causes heat stress (HS) resulting in altered growth, body composition and metabolic dysfunction in pigs. Grape seed extract (GSE) has been shown to reduce inflammation, and improve glucose transport and metabolism. Thus, GSE may be an effective supplement to combat the consequences of heat stress; however this possibility has not been evaluated in a large animal model. The objective of the current study was to examine the effect of GSE supplementation on pig performance and body composition during HS. Twenty-four female pigs (62.3± 8 kg BW) were randomly assigned to a 2X2 factorial experiment; thermal neutral (TN; 21-22°C) or heat stress conditions (HS; 33-34°C) for 7 days and fed either a control or a GSE supplemented diet (12mg/kg body weight). Body temperature (TB), respiration rate (RR) and feed intake (FI) were measured daily. Body composition was measured by dual-energy X-ray absorptiometry (DXA). Respiration rate and TB increased in the HS control group compared to the TN control group (p<0.05), however GSE did not alter these parameters compared to control for the duration of the 7 day period. HS decreased FI (P < 0.05). Fasting blood glucose concentrations were approximately 1.5-fold greater in the control diet compared to their GSE supplemented counterpart (p=0.067) on day 6 of the HS period, but did not differ between groups at the end of day 7 of HS. Body composition analysis indicated bone mineral density, bone mineral content, and percent change of fat remain unchanged between treatment groups. Percent change in weight was significantly reduced in HS. Lean tissue accretion was 45% greater in TN compared to HS groups (p<0.05). Endotoxin concentrations were approximately 2-fold lower in the HS-GSE group compared to the control (P=0.083). Grape seed extract supplementation does not appear to alter pig growth performance or body composition, but does appear to delay the onset of reduced feed intake by 1 day, reduce intestinal permeability, and improve insulin sensitivity during additional stress. / Master of Science in Life Sciences

A set of 37 strains including 13 serotypes of Listeria monocytogenes (Lm) were analyzed for heat tolerance at 60°C for 10 min and further categorized into three groups; low (strains with <2 log survival), medium (2-4 log survival), and high (4-6 log survival) heat tolerant. When Lm strains representing each group were subjected to sub-lethal heatstress at 48°C prior to 60°C, the survivals of all strains were increased by at least 5 log CFU/ml when compared to controls. Sub-lethal heat-stress at 48°C for 30-60 min increased the heat-stress resistance of Lm strains by doubling D60°C values from 1.9-4.3 to 5.0-10.4 min. When Lm cells were cooled after sublethal heat-stress at 48°C prior to 60°C treatment, such acquired heat-stress adaptation was unstable at 22°C but was found to be highly stable for up to 24 h at 4°C. These results will have potential implications in food safety risk analysis for Lm.

No description available.

Weather affects agriculture more than any other variable. For centuries, growers had to depend upon small bits and pieces of local climatological data collected and passed down in almanacs. Over the last 100 years, however, scientists have developed complex Numerical Weather Prediction (NWP) models that are able to forecast weather with increasing accuracy. The objective of this work was to use a probabilistic NWP model (the European Centre for Medium-Range Weather Forecasts (ECMWF) Ensemble Prediction System (EPS)) as a component to couple with agricultural decision-making tools and models. First, customized ECMWF EPS forecasts were used as an irrigation scheduling aid for a field trial. Next, the CROPGRO Cotton Model was used to simulate the field experiment as well as an additional irrigation scheduling strategy. Finally, a cotton canopy temperature model was developed and coupled with customized ECMWF EPS forecasts to generate hourly canopy temperature forecasts. These forecasts were used to create a heat stress warning system. Results from the field trial indicate that using precipitation forecasts to schedule irrigation could provide a convenient alternative relative to a standard method. Results from the simulated field trial suggest using precipitation forecasts issued on the day of irrigation could be more efficient than using forecasts issued one to two days prior. Last, results from the heat stress project indicate forecasts were skillful to 10 days, allowing enough time for growers to protect crops if needed. In light of the above, implications for the agricultural community could be significant. Coupled atmospheric-agricultural models have the ability to put weather forecasts in terms producers can understand and can quickly use to make strategic on-farm decisions, therefore, possessing the potential to make a large positive global impact.

Four studies were conducted to evaluate the effects of supplemental cooling and niacin on heat stress (HS) responses in vivo and in vitro in lactating dairy cows. For experiment one, lactating dairy cows were fed four levels of dietary niacin, NIASHURE® (0,4,8,12 g/d) for 21 d. Heat stress decreased niacin levels in whole blood, red blood cells and plasma as compared to thermoneutral. Water intake, plasma and milk niacin concentrations increased linearly with increasing dietary niacin in HS cattle. In thermoneutral, but not HS cows, niacin increased skin temperature compared to controls suggesting niacin increased skin blood flow and sensible heat loss. In experiment 2, lactating cows were used to evaluate the impact of feed-line soaking (FLS) combined with niacin supplementation. In evaporative cooled barns, FLS reduced body temperatures; however the addition of niacin did not improve heat status of these cows. For experiment 3, 200 lactating dairy cows were used to determine the effects of conductively cooled bedding (CC) compared to feed-line soaking with fans (FLSF). Conductively cooled bedding can reduce skin and vaginal temperatures in cows after nighttime rest. However, FLSF were more effective in decreasing body temperature, as cows had lower heat parameter indices, higher milk yield and longer rest time. For experiment 4, three cell types were used to evaluate niacin in vitro. Niacin induced heat shock proteins (HSP) that protected cells during HS in transformed bovine mammary epithelial cells but not in primary bovine mammary epithelial cells (BMEC) or bovine endometrial cells (BEND). Effect of niacin on HSP may depend on enzymes involved in DNA-binding activity of heat shock factor 1. These results suggest that niacin may be involved in whole body metabolism during heat stress and is cell dependent. We did not find dietary niacin to be commercially efficacious in treating HS in cows. Further research is warranted to improve efficacy of CC and FLSF under high temperature humidity index conditions.

Heat stress-induced hyperthermia and exercise-induced hypohydration are associated with marked alterations in limb and systemic haemodynamics in humans. However, the mechanisms underlying these alterations their effects on muscle blood flow are not well understood. The present thesis examined whether whole body and local heat stresses increased limb skin and muscle blood flow (Study 1) and whether hypohydration and hyperthermia compromised leg muscle, skin and systemic haemodynamics (Study 2). The effects of heat stress and combined hypohydration and hyperthermia were examined at rest and during mild small muscle mass exercise in humans. The results from Study 1 suggested that heat stress was accompanied by vasodilation in both skeletal muscle and skin vasculatures. Therefore in line with concomitant elevations in blood flow, skeletal muscle and skin vasodilation contribute to increases in leg blood flow and vascular conductance with whole body heat stress. Furthermore, increases in leg muscle and skin blood flow with isolated elevations in leg tissue temperature accounted for at least one half of the total increase in leg blood flow with whole body heat stress. Enhanced leg blood flow owed to a net vasodilation as explained by an elevation in vasodilator activity that exceeded increases in vasoconstrictor activity. This phenomenon was closely related to increases in muscle temperature and intravascular adenosine triphosphate (ATP). The results from Study 2 demonstrated that mild and moderate hypohydration and hyperthermia do not compromise leg muscle and skin blood flow or cardiac output at rest or during mild exercise in humans. Furthermore, acute rehydration did not alter leg muscle and skin blood flow or cardiac output compared to hypohydration and hyperthermia despite large alterations in blood volume and haematological variables and the restoration of core temperature. Taken together, the findings of this thesis indicate that: 1) heat stress induces vasodilation in both skeletal muscle and cutaneous vasculature, 2) elevations in muscle temperature and intravascular ATP play a role in heat stress- and exercise-induced hyperaemia, and 3) moderate hypohydrationinduced hypovolemia and haemoconcentration and rehydration-induced hypervolaemia and haemodilution do not alter leg blood flow or cardiac output at rest and during low intensity exercise in humans when a large cardiovascular reserve is available.

No description available.

Doctor of Philosophy / Department of Agronomy / Allan K. Fritz / Heat and drought stress are two of the most significant abiotic stresses limiting wheat production in the Great Plains and worldwide. Introgression of novel tolerance genes from wild relatives is a strategy which presents promise. This study examined both heat and drought tolerance from the tetraploid species Aegilops geniculata (U[superscript g]U[superscript g]M[superscript g]M[superscript g]). Additional screening for heat tolerance was conducted with the US genome species Aegilops peregrina (Hack) and Aegilops kotschyi (Boiss). A comprehensive screening system for drought tolerance was also constructed to evaluate wheat and its wild relatives. Previous reports suggested that Ae. geniculata accession TA2899 was moderately tolerant to heat stress. It had also previously been used to develop a full set of wheat-Ae. geniculata chromosome addition lines in a Chinese Spring background. To identify the chromosome(s) carrying the heat tolerance, all addition lines, as well as wheat check genotypes, were screened for post-anthesis heat tolerance in two growth chamber experiments. No chromosome addition lines were significantly different (p<0.05) from Chinese Spring, and none were found to have superior performance to the positive check cultivars. Forty-five accessions of Ae. peregrina and its close relative, Ae. kotschyi were screened in a post-anthesis heat experiment. A follow-up experiment compared the genotypes in a split-plot temperature treatment with heat and optimal growth chambers. Many accessions were similar to the control genotypes for grain fill duration, and some exceeded the wheat controls for relative chlorophyll index values on Day 12 and Day 16. TA1889 and TA1904, both Ae. peregrina accessions originating from Israel, had a higher grain fill duration across experiments than the best wheat control, and warrant further investigation. Previous reports suggested drought tolerance in Ae. geniculata. After preliminary screenings, six genotypes were selected for advanced screening and compared with three wheat cultivars. The advanced greenhouse screening system was conducted in 152cm tall PVC growth tubes. The experiment measured multiple plant responses, and had a datalogging system automatically collecting water content and matric potential of the growth media. Multiple accessions warranted further investigation, and showed potentially different modes of drought tolerance, with varying levels of stomatal resistance, biomass, and osmotic adjustment.

A degeneração testicular é a mais frequente afecção reprodutiva em machos e leva a queda da qualidade espermática e, consequentemente, da fertilidade. Uma das principais causas é o estresse térmico, sendo caracterizada pelo aumento na produção de espécies reativas ao oxigênio, assim, substâncias antioxidantes podem reduzir os impactos negativos ao sêmen desses animais. A melatonina tem alto fator antioxidante, além de atuar na proteção ao DNA espermático e na regulação da apoptose. O presente estudo teve por objetivo avaliar os efeitos do tratamento exógeno com melatonina de longa ação sobre a recuperação do quadro de degeneração testicular em touros da raça Nelore. Para tal, foram realizados dois experimentos. O experimento 1 foi realizado para definir a dose exógena de melatonina (diluída em veículo oleoso e administrada por via intramuscular) que provocaria aumento por tempo prolongado na concentração sérica da mesma em bovinos. Foram utilizadas nove vacas ovariectomizadas distribuídas em três grupos: Controle (somente veículo oleoso); Melatonina 18 mg/50 kg de peso vivo; e Melatonina 27 mg/50 kg de peso vivo. Foram colhidas amostras de sangue no dia da aplicação e 4, 8, 16 e 24 dias após. A concentração de melatonina foi dosada pela técnica de ELISA. Os dados foram analisados utilizando o software Statistical Analysis System (SAS), pela ANOVA, adicionando-se o fator medidas repetidas no tempo. As probabilidades de interações ao longo do tempo foram determinadas pelo comando RANDOM (PROC GLIMMIX do SAS), com nível de significância de 5%. A aplicação de melatonina intramuscular diluída em veículo oleoso, na concentração de 18 mg/50 kg de peso vivo, provocou aumento estável por oito dias na concentração sérica de melatonina em bovinos. No experimento 2 foi avaliado o tratamento com melatonina sobre a degeneração testicular em touros, utilizando a dose estabelecida no experimento 1. A degeneração testicular foi induzida pela colocação de bolsas insuladoras testiculares por 96 horas. Foram utilizados 22 touros da raça Nelore distribuídos em 4 grupos: CON - touros não induzidos à degeneração testicular e não tratados (n=5); DT - touros induzidos à degeneração testicular e não tratados (n=6); ME - touros não induzidos à degeneração testicular e tratados com melatonina exógena (n=5); e DTME - touros induzidos à degeneração testicular e tratados com melatonina exógena (n=6). Foram realizadas colheitas de sêmen e sangue semanalmente, iniciando-se duas semanas antes da colocação das bolsas testiculares; no dia da retirada; e por mais 11 semanas após. Foram analisadas as características clínicas, tais como perímetro escrotal, consistência testicular, homogeneidade testicular (presença de pontos hipercóicos) e hemodinâmica do parênquima e plexo pampiniforme e índice de resistência vascular. As características seminais avaliadas foram volume, concentração, motilidade e vigor subjetivos, análise computadorizada dos espermatozoides, membranas plasmática, acrossomal e mitocondrial, morfologia espermática, peroxidação lipídica e bioquímica do sêmen. O plasma sanguíneo foi utilizado para avaliar a peroxidação lipídica e componentes bioquímicos (proteína total, albumina, GGT, AST, ALT, creatina quinase, triglicérides, colesterol, HDL, BHB e NEFA). Os dados foram analisados utilizando o software SAS, pela ANOVA, adicionando-se o fator medidas repetidas no tempo. As probabilidades de interações ao longo do tempo foram determinadas pelo comando RANDOM (PROC GLIMMIX do SAS), com nível de significância de 5%. A insulação provocou queda na consistência testicular, motilidade, integridade das membranas plasmática e acrossomal e no potencial de membrana mitocondrial, bem como aumentou os defeitos espermáticos e a peroxidação lipídica. O tratamento com melatonina não mostrou influência sobre as características clínicas; contudo, apresentou melhora no vigor (p=0.05), na motilidade total (p=0.05) e no potencial mitocondrial (p=0.003) 15 dias após a aplicação da melatonina. Além disso, a melatonina diminuiu os valores de HDL, colesterol e BHB. O tratamento da degeneração testicular em touros (28 dias após a insulação) utilizando melatonina exógena em veículo de liberação lenta, na dose de 18 mg/kg, é eficiente em melhorar características de vigor, motilidade e potencial mitocondrial espermático. / Testicular degeneration is the most frequent reproductive affection in males and leads to a decrease in sperm quality and, consequently, fertility. One of the main causes is heat stress, being characterized by the increase in the production of reactive oxygen species, thus, antioxidant substances can reduce the negative impacts to the semen of these animals. Melatonin has a high antioxidant factor, besides acting in the protection of sperm DNA and in the regulation of apoptosis. The present study aimed to evaluate the effects of exogenous treatment with long acting melatonin on the recovery of testicular degeneration in Nellore bulls. Therefore, two experiments were conducted. Experiment 1 was performed to define the exogenous dose of melatonin (diluted in oily vehicle and administered intramuscularly) which would cause a prolonged increase in serum concentration of melatonin in cattle. Nine ovariectomized cows were divided into three groups: Control (only oily vehicle); Melatonin 18 mg/50 kg of body weight; and Melatonin 27 mg/50 kg of body weight. Blood samples were collected on the day of application and at 4, 8, 16 and 24 days after administration. The melatonin concentration was measured by ELISA. The data were analyzed using the Statistical Analysis System (SAS) software, by ANOVA, adding the factor repeated measures in time. The probabilities of interactions over time were determined by the RANDOM command (PROC GLIMMIX from SAS), with a significance level of 5%. The application of intramuscular melatonin, diluted in oily vehicle at the concentration of 18 mg/50 kg of live weight, caused stable increase for eight days in the serum concentration of melatonin in cattle. In experiment 2 was evaluated melatonin treatment on testicular degeneration in bulls, using that dose assessed in the experiment 1. Testicular degeneration was induced by the placement of testicular insulation bags for 96 hours. Twenty two Nelore bulls were distributed in 4 groups: CON - bulls not induced to testicular degeneration and untreated (n = 5); DT - bulls induced to testicular degeneration and untreated (n = 6); ME - bulls not induced to testicular degeneration and treated with exogenous melatonin (n = 5); and DTME - bulls induced to testicular degeneration and treated with exogenous melatonin (n = 6). Semen and blood samples were collected weekly, starting two weeks before the placement of testicular bags; on the day of removal; and for another 11 weeks thereafter. Clinical characteristics such as scrotal perimeter, testicular consistency, testicular homogeneity (presence of hypercoic points) and parenchyma and pampiniform plexus hemodynamics and the vascular resistance index were analyzed. The seminal characteristics evaluated were subjective volume, concentration, motility and vigor, computerized analysis of spermatozoa, plasma, acrosomal and mitochondrial membranes, sperm morphology, lipid peroxidation and biochemistry of semen. Blood plasma was used to evaluate lipid peroxidation and biochemical components (total protein, albumin, GGT, AST, ALT, creatine kinase (CK), triglycerides, cholesterol, HDL, BHB and NEFA). Data were analyzed using the SAS software by ANOVA, adding the factor repeated measures in time. The probabilities of interactions over time were determined by the RANDOM command (PROC GLIMMIX from SAS), with a significance level of 5%. Insulation caused reduction on testicular consistence, motility, integrity of plasma membranes, integrity of acrosome, mitochondrial potential, as well as increased sperm defects and lipid peroxidation. Treatment with melatonin showed no influence on clinical characteristics, however, showed improvement in vigor (p = 0.05), total motility (p = 0.05) and mitochondrial potential (p = 0.003) 15 days after melatonin application. Besides that, melatonin decreased HDL, cholesterol and BHB values. The treatment of testicular degeneration in bulls (28 days after insulation) using exogenous melatonin in a slow-release vehicle, at a dose of 18 mg/kg, is efficient in improving sperm characteristics of vigor, motility and mitochondrial potential.