Effects of high ambient temperature in rabbits: metabolic changes, caecal fermentation and bacterial flora.

Abstract

Eighteen male New Zealand White rabbits, randomly assigned to three groups, were placed in a climatic chamber at 20 ºC. After 10 days of adaptation the temperature was risen every day to 30ºC from 08:00 a.m. to 08:00 p.m. The three groups of animals were slaughtered according to the following schedule: six animals at the end of adaptation period (control), six animals 2 days after the beginning of the heat stress, and six animals 14 days after the beginning of the heat stress. At the same schedule blood samples were collected through the ear vein. The exposure to hot environment induced a net decrease of feed consumption in the first two days that was partially recovered in the following days. No relevant changes were observed for plasma metabolic parameters concentration in the different sampling times, except for an increase of total proteins on day 2, and a tendency to decrease for glucose on day 2 and 14 (P<0.08). Total volatile fatty acids concentration in the caecal content significantly decreased on day 2 and 14 and a parallel trend was observed for acetic, propionic and butyric acid concentration. No relevant changes were observed in the molar proportion of acetic, propionic and butyric acid and pH. Ammonia concentration of the caecal content decreased on day 2. Total anaerobes significantly increased on day 2, clostridia significantly increased on day 2 and 14. No significant changes were recorded for lactobacilli and total coliforms.