Physiological response of rabbits to a thermoducting environmental enrichment during variable environmental stress conditions.

Abstract

The objective was to evaluate the efficacy of a thermoducting environmental enhancer (EAT) in reducing surface body temperature (BT) in stressed rabbits. Stress was estimated using the ITH. Twelve multiparous rabbits were randomized into two groups: one with and one without the EAT, which consisted of a 1.5-liter bottle of frozen water. TC was measured using a FLIRTG267 thermographic camera at the base of the right ear at 10:00, 12:00, and 16:00 for 16 days. Environmental temperature (ET) and relative humidity (RH) were also measured to estimate ITH (ITH=ET-((0.31-0.31(RH/100))*(ET-14.4))). ITH was classified as absent (ITH≤27.9), moderate (28.0≤ ITH≤28.8), or high (ITH≥28.9). A GLM mixed-effects model was performed which included the presence or absence of the EAT as a fixed effect and doe and day as random effects. From 10:00 to 12:00 and from 12:00 to 16:00, 50% of the time, the animals experienced high environmental stress. From 10:00 to 12:00, 75% of the time, the animals experienced no environmental stress. Moderate environmental stress occurred 18.8% of the time at 10:00, 25% of the time at 12:00, and 12.5% of the time at 16:00. Modeling showed the effect of the presence of EAT and ITH at all hours (p < 0.01) and their interaction at only 12:00 (p < 0.05). At 10:00, the TC of the CON-EAT group was higher (p < 0.05), regardless of ITH category (SIN-EAT: 31.8 °C; CON-EAT: 32.2 °C). At 12:00 (SIN-EAT: 31.8 °C; CON-EAT: 32.2 °C) and 16:00 (SIN-EAT: 32.9 °C; CON-EAT: 31.7 °C), the CT of the CON-EAT group was lower in all ITH conditions (p < 0.01). In conclusion, EAT was effective in reducing surface CT in rabbits during hours of high environmental stress. At 10:00, this did not occur due to the absence of EAT.