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Title:Temperature and correlated physiologic responses as indicators of well-being
Author(s):Suchomel, Justin
Advisor(s):Salak-Johnson, Janeen L.
Department / Program:Animal Sciences
Discipline:Animal Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Abstract:It is well documented that young pigs are highly susceptible to stress, and body temperature in young pigs is altered in response to a variety of stressors. Exposure to pathogens, extreme fluctuations in ambient temperature and social stress may all result in dramatic changes in core body temperature. Neonatal piglets have a very limited thermogenic capacity, making them highly susceptible to chilling and disease. While improvements in piglet husbandry, nutrition, and management have benefited swine in production settings, another effective means of maintaining a high level of piglet well-being would be to limit the effects of stressors by being better able to identify the early signs of the stress response in piglets to various stressors. This has proven to be a difficult challenge for researchers because easily identifiable objective measures that signal the onset of a stress response have not been well identified. Deriving correlations between temperature and changes with other physiologic measures during the stress response would validate whether it is possible to use body temperature as an indicator of changes in well-being in response to various stressors in young pigs. Chapter 1 examined the effects of feeding a gestation diet supplemented with a plant-extract, “capsicum”, to sows to assess its modulatory effects on thermogenic and immune effects of their offspring. This was conducted across two experiments in which sows were fed either a gestation diet supplanted with capsicum for 2-wks prior to expected farrowing date (TRT-ST) or a standard gestation diet (CONT). In Experiment 2 an additional treatment was added feeding the treated diet for the entire gestation period (TRT-LT). In both experiments piglets were randomly assigned an age treatment (24 h or 72 h) and a challenge treatment (LPS or saline). The acute intraperitoneal injection of LPS was used to assess if piglets from sows fed TRT diet could evoke a more robust febrile response shortly after birth. It has been well documented that neonatal piglets have a minimal capacity to thermoregulate, thus improving thermogenic capacity might reduce the number of animals that succumb to chilling. However, thermogenic ability was not vastly improved as rectal temperature in response to LPS was not greater in piglets from sows fed a TRT-diet compared to piglets from sows fed a CONT-diet. However, piglets from sows fed TRT-diet had different immune status. Plasma levels of cytokines were altered by TRT-diet. Piglets from sows fed TRT-ST diet and injected with LPS had lower plasma levels of interleukin-12 (IL-12), an inflammatory cytokine compared to piglets from sows fed CONT diet. However, feeding TRT-LT diet to sows did not alter piglet IL-12 levels. Interleukin-10 (IL-10), on the other hand, was altered in piglets whose dams were fed TRT-diet. Feeding a diet supplemented with capsicum to sows seems to have modulatory effects on the immune response of her piglets, but had little effect on their thermogenic ability. Chapter 2 explored correlations between body core temperature and other physiologic responses as indicators of well-being by subjecting weaned pigs to various stressors. Pigs were mixed and acutely challenged with LPS in experiments 1 and 3. In experiment 2, pigs were also challenged repeatedly with LPS to simulate a chronic exposure to the immunogen and to assess methods of a chronic LPS challenge. In experiment 3, pigs were cold stressed and acutely challenged with LPS. Pigs were implanted with RFID thermosensors near the anterior jugular vein and in the flank fold, two locations that had previously been determined to be representative of pig core body temperature. Acute LPS challenge resulted in increased body core temperature but with variable results across groups. In experiment 1, acute challenge with LPS resulted in greater (P <0.05) pig rectal and jugular temperatures within 45 min post-injection compared to saline-injected pigs. However, flank fold temperature was not altered by LPS. In experiment 3, regardless of ambient temperature, rectal temperature was greater (P <0.01) in LPS-injected pigs at 4 h post-injection compared to saline-injected pigs. Pigs also had increased rectal temperatures (P < 0.05) at various times following mixing in experiments 2 and 3. In experiment 2, pig rectal and jugular temperatures were greater (P < 0.05) at 2 h post-injection among those treated chronically with LPS + peanut oil compared to pigs treated with peanut oil only. There was no difference in rectal or jugular temperatures of pigs treated with LPS + saline compared to pigs treated with saline only. Pig body temperature decreased in response to cold. In experiment 3, pigs housed in cold ambient temperature (COLD 50 F) during both mixing and LPS challenge had lower rectal temperature (P <0.01) than did pigs kept at a thermoneutral ambient temperature (TNT). Regardless of whether pigs were subjected to cold stress, pigs injected with LPS (71.52 ng/mL ± 11.04) had greater (P < 0.05) plasma cortisol levels than did saline-treated pigs (52.00 ng/mL ± 10.86). Concurrently, pig behavior was changed in response to acute LPS challenge and cold stress. Pigs injected with LPS spent less time drinking, eating, and fighting (P < 0.05) than did saline-injected pigs. Pigs kept in a COLD spent greater (P < 0.05) time sitting in contact with other pigs compared to pigs in TRT chamber, regardless of LPS treatment. Social status also played a role in the response pigs had to LPS and cold stress. In experiment 3, intermediate (INT) piglets injected with LPS had greater (P < 0.05) rectal temperature compared to either dominant (DOM) or submissive (SUB) pig. The DOM pigs spent greater (P < 0.05) time drinking than did other pigs. Surprisingly, when challenged with LPS and kept in cold temperature, SUB pigs spent greater (P < 0.05) time eating than did either DOM or SUB piglets. Monitoring changes in body temperature can be an easy and effective physiologic indicator of exposure to stress, but it must be understood that a change in body temperature might not indicate an impingement on pig well-being. To effectively assess piglet well-being, other parameters should be incorporated into the assessment of the animal.
Issue Date:2012-05-22
Rights Information:Copyright 2012 Justin Suchomel
Date Available in IDEALS:2012-05-22
Date Deposited:2012-05

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