Eight male unacclimatized subjects were selected for the present investigation. The subjects were all in excellent health and ranged in age between 25 and 35 years. Subjects performed one-dimensional horizontal compensatory tracking, the Critical Instability Tracking Task (CITT), in each of eight environmental conditions for an hour. Two levels of ambient temperature were used: 22°C (72°F) and 35°C (95°F). Two levels of relative humidity were used: 45% RH and 80% RH. The resulting Wet-bulb Globe Temperatures were 18°C (64°F) WBGT, 21°C (70°F) WBGT, 29°C (85°F) WBGT, and 34°C (93°F) WBGT. Two levels of tracking difficulty were used: easy ()λlow = 1.0 and λhigh = 2.0) and moderate (λlow = 1.0 and λhigh = 5.0). Prior research has demonstrated that both ambient temperature and tracking difficulty affected significantly tracking performance (root-mean-square error) and perceived workload (SWAT rating). However, in this study, humidity did not affect either measure significantly. This might be attributable to the upper bound of humidity (80% RH) used in this research. Therefore, research needs to be done above 80% RH to examine the effects of humidity in further detail. Results also indicated that the Subjective Workload Assessment Technique (SWAT) can be used as a good indicator of the actual changes in mental workload on tracking in heat. Finally, results showed that tracking performance decrement occurred at a lower temperature (29°C (85°F) WBGT) than did the perception of significant mental workload on tracking (which occurred at 34°C (93°F) W8GT). / Master of Science

A 2 x 2 x 4 factorial experiment utilizing 640 male Large White turkeys was conducted to determine the effects of neonatal/juvenile heat stress and tryptophan supplementation upon growth to 129 days of age, as well as meat quality and brain neurotransmitter levels. Treatments consisted of neonatal heat stress (36 continuous hours at 38 C) starting at 5 days of age, juvenile heat stress (8 hours a day at 38 C for 5 consecutive days) starting at 106 days of age, and tryptophan supplementation (0, .1, .2, and .3 % added to the diet) from 112 days of age to market (129 or 138 days of age). Feed consumption, weight gain, and mortality were l recorded and selected meat quality measurements and brain neurotransmitter levels were determined. Weight gain and feed consumption were significantly reduced by juvenile heat stress treatment while early stress, late stress (EL) treatment significantly increased mortality as compared to CC treatment during this period. Such findings revealed that neonatal heat stress did not reduce losses due to heat stress at market age. After live haul, (129 days of age), EC birds had significantly greater cooking loss as compared to birds of the other three treatments and CC birds had significantly larger thigh weights than EL treated birds. In birds analyzed at 138 days of age, CL treatment resulted in a significantly higher Hunter L-value (lightness) in pectoralis major tissue as compared to CC treatment, indicating a darkening of pectoralis musculature due to juvenile heat stress treatment. Tryptophan supplementation resulted in no significant differences in food intake, body weight, or body weight gain. Serotonin, 5 hydroxyindole acetic acid (5-HIAA), and norepinephrine levels increased linearly with dietary tryptophan supplementation in the four brain regions analyzed while linear increases in L-dihydroxyphenylalanine (L·DOPA) occurred in all regions analyzed except for the cerebellum due to Lâ tryptophan supplementation. Plasma levels of serotonin also increased in a positive dose-response fashion while tryptophan supplementation at all levels significantly reduced norepinephrine levels as compared to the basal diet. The addition of .1% tryptophan to the tinisher diet significantly increased carcass weight and thigh weights while no significant differences occurred in breast protein and ether extract, or in either pectoralis major and biceps femoris shear or Hunter color values due to supplemental tryptophan. / Master of Science

Call number: LD2668 .T4 1979 O43 / Master of Science

In experiment 1, fourteen cows were blocked for milk yields and balanced for days in lactation. Treatments were: (1) Air conditioning (AC), five cows; (2) Evaporative cooling (EC), four cows; and (3) Conventional shade (S), five cows. Sequential samples were taken for 8 h at 12 min intervals starting at 2200 and then at hourly intervals for 13 h. Serum was assayed for insulin, thyroxine (T4), triiodothyronine (T3) and cortisol using a double-antibody radioimmunoassay procedure. Free fatty acids (FFA) were determined in serum by an enzymatic method. In experiment 2, ten cows were blocked for milk yields and days in lactation. Treatments were: (1) Evaporative cooling (EC), five cows; and (2) conventional shade (S), five cows. Blood was drawn at 60 and 90 d of lactation. Blood sampling, hormone and FFA assays were carried out as in experiment 1. Sequential samples were taken for 8 h at 12 min intervals starting at 2300 and then at hourly intervals from 1030 to 1830. In experiment 1, insulin was depressed (P <.05) treatment effects for T3 in either experiment. There were significant treatment differences (P <.05) in respiration rates and body temperatures in experiment 1. Shade were higher than AC or EC cows. These studies demonstrated that summer heat stress depressed insulin and increased FFA with variable effects on T4 and cortisol but no effect on T3.

One hundred and twenty lactating Holstein cows in mid-lactation were offered diets varying in protein level and degradability at two locations during hot and moderate weather. Treatments were: (1) High protein (19%), high degradability (65%); (2) High protein (19%), medium degradability (40%); (3) Medium protein (15.5%), high degradability (65%); (4) Medium protein (15.5%), medium degradability (40%). Diets were individually fed during hot weather at the University of Arizona Dairy Farm and contained 38.4% alfalfa hay, 12.4% cottonseed hulls, 9.8% whole cottonseed, and 39.4% concentrate (dry matter). Diets were group fed during moderate weather at the Brigham Young University Dairy Farm, Provo, Ut, and contained 31.3% corn silage, 14% alfalfa haylage, 9.4% whole cottonseed and 45.3% concentrate (dry matter). Average daily ambient temperatures were 35.1°C for hot and 26.8°C for moderate weather locations. Fat-corrected milk (3.5%, 2 x milkings) and milk persistency were lower for treatment 1 than other treatments. For the respective treatments during hot weather means were: 23.4, 26.6, 28.5, 28.4 kg/d; 83.2, 91.2, 90.9, 90.3%; and for moderate weather means were: (3 x milkings): 34.7, 31.8, 32.2, 32.4 kg/d; 97.0, 93.4, 92.1, 90.3%. Dry matter intakes during hot weather were 21.5, 21.9, 23.3, and 23.1 kg/d. Respiration rate and rectal temperature during hot weather were: 90.1, 87.9, 90.9, 94.7 counts/min; 39.0, 39.3, 39.3, 39.5°C and for moderate weather: 61.2, 58.2, 55.5, 67.4 counts/min; 38.8, 38.6, 38.7, 38.8°C. Serum T₃,T₄ and cortisol were generally unaffected by treatment, but were depressed during hot weather. Serum glucose was not significantly affected by treatments at either environmental locations. Animals consumed more water with highly degradable protein diets at each location along with consuming more water during thermal stress. These data show that 3.5% fat-corrected milk and milk persistency are significantly affected (P <.01; P <.025) by rations high in protein of high degradability during heat stress.

Increased environmental heat causes early embryonic death before implantation. This study was designed to examine tissues of dams exposed to environmental temperatures of 36°C and to examine 72 hour old embryos from these dams. Results showed adult mice exposed to heat stress had significant changes in liver morphology with hepatocyte swelling and vacuolization of the cytoplasm, organelles in the hepatocytes were displaced next to the cell membrane. After 48 hours of recovery from heat stress, liver morphology appeared normal. Embryos from heat stressed dams had delayed development indicated by increased 2alpha helical cellular inclusions. Embryos responded differently to different fixation techniques indicated permeability changes in either the zona pellucida or cellular membranes. Litter size or pup survivability from heat stressed dams allowed to recover indicated changes seen at this point were reversible

The basis of this investigation is to characterize growth property differences in normal versus virally transformed cells. Using a temperature-sensitive mutant of Rous sarcoma virus, the cells' transformation state is regulated by the growth temperature; at 33°C the cells are transformed, while at 39°C the cells have normal characteristics. The morphology of NRK cells is elongated and fibroblastic; when transformed the cells are rounded. Normal cells grow to a monolayer and stop, while transformed cells grow to saturation densities greater than just a monolayer amount. Transformed cells can form foci when grown in mixture with normal cells. Normal cells must be in contact with the culture vessel in order to grow, but transformed cells lack anchorage dependence for growth.

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