title: The effects of elevated temperature and humidity on rectal temperature and respiration rate in the New Zealand white rabbit.
abstract: In 2 replicated factorial experiments, 7-h climate chamber exposures were used to study the responses of adult NZW rabbits to a range of elevated temperatures and humidities. At 18 mm Hg water vapour pressure, 23.8 degrees C was well tolerated, rectal temperature (RT) and respiration rate (RR) averaging 38.6 +/- 0.3 degrees C and 82.9 +/- 15.5 breaths/min, respectively. Both parameters were elevated (P less than 0.001) at 32.2 degrees, 37.8 degrees and 43.3 degrees C. RT and RR reached plateau levels of 39.5-40.1 degrees C and 410-460/min at 32.2 degrees C, which was tolerated for the full 7-h test period. Test temperatures of 37.8 degrees and 43.3 degrees C, on the other hand, could be tolerated for only 80 and 40 min respectively, before RT reached the safe upper limit of 41.7 degrees C. Final RR values at 37.8 degrees and 43.3 degrees C were 701.6 +/- 42.7 and 812 +/- 55.1/min, respectively. In a 34.5 degrees C atmosphere a humidity of 21 mm Hg water vapour pressure was classified as "dry", and was tolerated for 323 +/- 123 min. RT and RR increased by 0.6 degrees C and 316/min during the first 20 min of exposure (P less than 0.05). Thereafter both parameters increased progressively, but with no significant differences between successive recording periods, until RR reached 550.3 +/- 88.8/min at 41.7 degrees C RT. Humidities of 25, 29 and 33 mm Hg water vapour pressure were, on the other hand, classified as "wet" and were tolerated for only 92 +/- 22, 81 +/- 16 and 119 +/- 50 min, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Animal Science, University of New England, Armidale, NSW, Australia.
authors.forename: W
authors.initials: W
authors.lastname: Kasa
authors.forename: C J
authors.initials: CJ
authors.lastname: Thwaites
mesh_terms: D000818:Animals; D001831:Body Temperature; D006358:Hot Temperature; D006813:Humidity; D011817:Rabbits; D012119:Respiration; D014887:Weather