Browsing by Subject "Swine -- Physiology"
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Item Acute stress effects on pig performance, immunity, and behavior(Texas Tech University, 1996-08) Hicks, Tiffanie AStress activates the hypothalamic-pituitary-adrenal axis (HPA). Corticotropin-releasing hormone (CRH) is the primary initiator of the stress response. The hypothalamus releases CRH which in turn stimulates the anterior pituitary to secrete adrenocorticotropin hormone (ACTH) and other peptides. Increased ACTH levels stimulate the adrenal cortex to release glucocorticoids. Stress not only effects the neuroendocrine and endocrine systems, but also alters behavior, immunity and overall physiology. The objectives of these studies were to (1) determine if physiological concentrations of various hormones had an effect on in -vitro NK cytotoxicity in pigs, and (2) to determine the effects of three common stressors (heat, cold and shipping) on pig performance, physiology and behavior. In experiment 1, peripheral blood was collected from 59 pigs to determine the effects of physiological concentrations of stress hormones on porcine natural killer cell (NK) activity. A standard cytotoxicity assay was utilized with peripheral blood mononuclear cells and 51Cr-labeled K-562 target cells. Hormones and concentrations were: porcine corticotropin releasing hormone (pCRH) at 0, 0.47, 4.7, 47 and 467 ng/mL; P-endorphin at 0, 0.001, 0.01, 0.1, 1, 10 and 100 ng/mL, Cortisol at 0, 3.6, 36 and 360 ng/mL, adrenocorticotropic hormone (ACTH) at 0, 0.045, 0.45, 4.5 and 45 ng/mL, epinephrine at 0, 0.022, 0.22, 2.2 and 21.9 ng/mL and norepinephrine at 0, 0.021, 0.21, 2.1, 20.6 ng/mL. Over the range of doses evaluated, pCRH, ACTH, Cortisol and norepinephrine had no significant effect on porcine NK activity. P-endorphin and epinephrine had significant (P < .01) effects on porcine NK activity. All doses of â-endorphin suppressed (P < .05) porcine NK activity. Porcine NK activity was greater (P < .05) when incubated with 0.22 ng/mL epinephrine than with 0.022 or 21.9 ng/mL epinephrine. These results suggest that physiological concentrations of CRH, ACTFI, Cortisol, and norepinephrine alone do not modulate pig NK activity. â-endorphin seems to be a potent suppressor of porcine NK activity. Epinephrine influenced pig NK activity in a dose-sensitive manner. In the second study, 132 weanling pigs were used to investigate the effects of three common stressors (and a control) and differing social status on behavior, immunity, plasma Cortisol and blood chemical measures. Eleven blocks of 12 pigs each were evaluated. Each block contained four pens, established at weaning, and examined for outcome of agonistic interactions. Pigs were labeled socially Dominant (DOM), Intermediate (INT) or Submissive (SUB). Two weeks later, random pens of pigs experienced either a control treatment (CON) or for 4 hours they were either shipped (SHIP), heat stressed (HEAT) with overhead heat lamps in their home pens, or cold stressed (COLD) by direct application of water and an air current. A battery of physiological and behavioral measures were collected. Treatments did not influence body weights, however, percentage weight change during SHIP was greater (P < .001) than for other treatments (.23, -2.9, .72, .91% ± .96 for CON, SHIP, COLD, HEAT, respectively). Serum glucose was elevated (P = .02) for SHIP pig compared with other treatments. Serum Cortisol was decreased (P = .03) for HEAT compared with COLD and SHIP pigs. Social status influenced (P < .01) body weights at weaning and throughout the study with body weights heaviest for DOM pigs than INT and SUB pigs. Social status also influenced serum globulin, albumin/globulin (A/G) ratio, and Cortisol concentrations. Globulin decreased, while A/G increased in DOM pigs. SUB pigs showed an increase in Cortisol compared to DOM and INT pigs. An interaction between social status and treatment occurred for NK cytotoxicity at 50:1 E:T (P = .06). Socially DOM and INT pigs had higher NK cytotoxicity than SUB, COLD pigs. An interaction was also observed between social status and stress treatment for lymphocyte blastogenesis under Phytohemagglutinin mitogen. Among HEAT pens, the INT pigs had lower lymphocyte proliferation than SUB pigs, but were not different from the DOM pigs. Among SHIP pens, the INT pigs had higher lymphocyte proliferation than either the DOM or SUB pigs. In conclusion, social status had large effects on plasma Cortisol, globulin, A/G ratio, body weight and weight changes, although only acute shipping stress resulted in weight loss. Many immune and blood measures were not changed among acutely stressed pigs, however, the relationship between social status and LTA and NK cytotoxicity was disrupted during acute stress. Pig behavior was largely influenced across all stress treatments. COLD pigs had greater overall activity, including, feeding, standing and attacking and they had less lying behavior. The HEAT and SHIP pigs had depressed activity levels and spent more time lying. During acute stress, behavioral symptoms appears to be the most accurate and reliable indicator of stress.Item Effects of age and diet on digestive function in the young pig(Texas Tech University, 1982-08) Owsley, Walter FranklinNot availableItem Effects of Genetics, Unilateral Ovariectomy, Follicle Cautery and Exogenous Gonadotropin on Folliculogenesis in Swine(Texas Tech University, 1983-05) Brazier, Stephen GlennNot Available.Item Genotype effects on pig immunity(Texas Tech University, 1995-12) Kleinbeck, Samara NanceOutdoor intensive swine production systems are common m the United Kingdom and are being explored m the southern United States. The objectives of study 1 were to determine the effects of production system and genotype on piglet weight gain, blood hemoglobin, white blood cell numbers and Immunoglobulin G concentrations. These data showed that environment and age influenced piglet Hb levels and WBC and that genotype influenced IgG levels shortly after birth, hi the second part of the study, production systems and treatment levels of iron were studied to observe the effects to the measures observed m the first part of the study. Outdoor-reared piglets had some signs of stress, but had similar survival rates as indoor-reared Utters. However, these data showed that supplemental iron may not be necessary m outdoor production systems. Newer genetic lines of pigs are being used in indoor and outdoor production systems. The objectives of study 2 were to describe the effects of the maternal sow line genotype, environment, and the genotype by environment interactions on the same measures as in the first study along with neutrophil chemotaxis, Cortisol concentrations and lymphocyte blastogenesis. Exp-94 sows had lower lymphocyte blastogenesis (LTA) at lower mitogen doses and higher natural killer cell (NK) cytotoxicity than the C-15 sows. Experiment 2 sought to determine the effects of genotype on the immune system of nursery-age offspring of the experimental Lines bred to a common PIC 405 boar line. The Exp-94 X 405 pigs had higher WBC numbers compared to the C-15 X 405 pigs. The Exp-94 Ime had marginally increased immunity to viral disease and reduced systemic bacterial immunity than the C-15 line.Item Neuroendocrine mechanisms of central CRH and stress-induced behavior and immune changes(Texas Tech University, 1999-05) Fullwood, Steven DPrevious work in both pigs and rodents showed that central corticotropin releasing hormone (CRH) had a profound effect on behavior and immunity. CRH given in the lateral ventricle has a great effect on behavior, Cortisol concentration lymphocyte proliferation and leukocyte distributions in freely-moving pigs. The specific objective of this work was to describe the dose response relationships for behavioral and immune effects. Pigs were fitted with an icv cannula in the lateral ventricle and with a vena cava catheter for remote blood collections. Pigs were continuously video taped during the work. Pigs weighing about 20 kg were given no injection, saline, or saline containing 0.5, 5, 50 or 150 µg porcine CRH in pigs. Pigs' behavioral responses showed a significant dose-response to CRH for oral-nasal behavior and general activity. Peak increases in behavioral activation were found at 50 µg. Sequences of behaviors were seen to change with dose of CRH. Sequences of locomotor activity increased and maintenance behaviors decreased with CRH, whereas the sequence of behaviors in saline animals remained complex. Numbers of circulating leukocytes did not change over the range of doses of CRH examined. In conclusion, behavioral effects of central CRH were sensitive at a much lower dose than were immune changes and the behavioral response to icv CRH was dose dependent.Item Studies on the mechanism of carbon monoxide-induced coronary vasodilation(Texas Tech University, 1993-05) Wright, Jackie ADissolved carbon monoxide (CO) produces increased coronary flow, i.e., vasodilation, in isolated rat hearts. It has been suggested that CO may be part of the nitric oxide family of endogenous autacoids and neurotransmitters with physiologic effects. In order to more fully understand the actions of endogenous CO, we investigated the vasodilatory effects of 5% CO dissolved in Krebs-Henseleit buffer on ventricular function in isolated rat hearts and further investigated the mechanism of this vasodilation in porcine coronary artery rings. Dissolved CO (5%-CO 90%-O2 5%CO2) produced 6±2% vasodilation without a significant change in any ventricular function parameters in isolated isovolumic rat hearts. The control group of hearts (95% O2 5%-CO2) vasoconstricted 3±1%. Over the experimental time period only perfusion pressure rose significantly, and the developed pressure and the ±dP/dt (the first derivative of the developed pressure) declined in the control group. The comparison of the ventricular compliance curves revealed no significant differences between either the CO group or the control group compared to a group of hearts perfused with red blood cell-containing perfusate. The best indicators of cardiac work were heart rate and -dP/dt for the control group and heart rate and developed pressure for the CO group. In porcine coronary artery rings, 5% CO (5%-CO 90%-O2 5% CO2) dissolved in Krebs-Henseleit buffer produced a significant transient vasodilation in rings precontracted with 20mM potassium chloride (KCl), but not with 74.7mM KCl. A significant transient vasodilation was also seen at 3 x 10^-6M Prostaglandin F2a(PGF2a), but not at 3 x 10^-5M. In rings equilibrated in calcium-free Krebs-Henseleit buffer precontracted with 3 x 10^-6 M PGF2a, calcium transfer through receptor-operated channels was affected significantly only at 4.0 mM calcium chloride, but not at 0, 0.5, 1.5, 2.5, and 4.0 mM calcium. CO did not significantly affect calcium transfer through voltage-operated calcium channels in rings precontracted with 20 mM KCl. Our results demonstrate that CO does cause transient coronary vasodilation at low but not high doses of KCl and PGF2a but his vasodilation does not involve inhibition of calcium transfer through receptor- or voltage-operated calcium channels. the transient nature of this effect may be related to postulated physiologic effects.