Thermoregulatory profile of a newer genetic line of pigs

Researchers and producers alike have noted the increased susceptibility to heat stress exhibited by the newer genetic lines of pigs. A study was condu cted to gather baseline information on the effects of acute heat stress on total heat production (THP), respiratory quotient (RQ). respiration rate (R R), and rectal temperature (T-rectat) and to investigate the dynamic intera ction of these parameters in growing-finishing barrows. Sixteen moderate-le an growth barrows were randomly assigned to a set of treatments as dictated by a repeated 4 x 4 Latin square crossover design. Pigs were moved from an individual pen to an indirect calorimeter where one of four environmental treatments (18, 24, 28, 32 degreesC) were applied for 20 h. During the trea tment exposure RR, THP. RQ and T-rectat were measured. For the 2-week perio d between treatments, pigs were housed at thermoneutral (22 degreesC). THP was found to be 17-20% higher than the published standards but comparable w ith other contemporary studies. Respiration rate was found to be a leading indicator of stress. Published by Elsevier Science B.V.