Submitted to: Livestock Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 22, 2001
Publication Date: April 10, 2001
Citation: Brown Brandl, T.M., Eigenberg, R.A., Nienaber, J.A., Kachman, S.D. 2001. Thermoregulatory profile of a newer genetic line of pigs. Livestock Production Science 71:253-260. 2001. Interpretive Summary: This study was done to learn how pigs respond to warm and hot temperatures. Information that helps producers understand when an animal is in distress will help producers know when to react. An important measure is heat production or metabolism, which is important for design of building ventilation systems. We found that heat production of our pigs was substantially higher (20%) than expected from previous research. The highe heat production is probably due to the modern genetic line of lean pigs. Body temperature and rate of breathing were also greatly increased. Rate of breathing, easily measured by watching the animal, can be used by producers as an early sign of heat stress.
Technical Abstract: Researchers and producers alike have noted the increased susceptibility to heat stress exhibited by the newer genetic lines of pigs. A study was conducted to gather baseline information on the effects of acute heat stress on total heat production (THP), respiratory quotient (RQ), respiration rate (RR), and core body temperature (CBT) and to investigate the dynamic interaction of these parameters in growing-finishing barrows. Sixteen high-lean-growth barrows were randomly assigned to a set of treatments as dictated by a 4 x 4 Latin square crossover design. Pigs were moved from an individual pen to an indirect calorimeter where one of four environmental treatments (TRT) (18, 24, 28, 32C) was applied for 20 h. During the treatment exposure RR, THP, RQ and CBT were measured. For the two-week period between treatments, pigs were housed at thermoneutral (22C). Total heat production was found to be 17-20% higher than the published standards but comparable with other contemporary studies. Respiration rate was found to be a leading indicator of stress.