Circadian Temperature Rhythm of Laboratory Swine
Abstract:The circadian temperature rhythm (CTR) profile holds promise for monitoring the domestic pig's responses to stress and illness. In the present study we quantified the CTR profile of nine growing–finishing swine using a time-series, small-group design. Temperature was monitored using a probe implanted in the ear for 5 1/2 to 9 1/2 consecutive days while the unrestrained pigs were housed singly in pens. The dominant period of the temperature data was estimated with the autocorrelation function and then used in standard cosinor analysis to compute the amplitude (half of the distance between the highest and lowest value within the period), mesor (rhythm-adjusted mean), and acrophase (timing of the cosine maximum). To examine the effect of procedural stress on CTR, we compared data from the first 3 days with those from subsequent days. Eight of the nine (89%) pigs had CTR with a mean (± standard error) period of 23.6 (0.5) h, amplitude of 0.18 (0.02)°C, mesor of 38.7 (0.24)°C, and acrophase at 19:44 h. Mean mesor and acrophase were not different, but amplitude was lower (P = 0.03) during the first 3 days after instrumentation than during subsequent days. We conclude that: 1) laboratory-housed, unrestrained, growing–finishing swine have CTR; 2) our ear-based instrumentation protocol imposes acute stress as reflected in attenuated CTR amplitude during the first 3 days after instrumentation; and 3) CTR adaptation to stress appears to occur over time.
Document Type: Research Article
Affiliations: The University of Texas Health Science Center at Houston School of Nursing and The Texas Heart Institute at St. Luke's Episcopal Hospital, Houston, Texas 77030
Publication date: June 1, 2005
Comparative Medicine (CM), an international journal of comparative and experimental medicine, is the leading English-language publication in the field and is ranked by the Science Citation Index in the upper third of all scientific journals. The mission of CM is to disseminate high-quality, peer-reviewed information that expands biomedical knowledge and promotes human and animal health through the study of laboratory animal disease, animal models of disease, and basic biologic mechanisms related to disease in people and animals.
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