Respiratory frequency and cloacal temperature in broiler chickens submitted to high cyclic ambient temperature

Abstract

The aim of this study was to verify the effect of high cyclic ambient temperature on the respiratory
frequency and cloacal temperature in broiler chickens. Seventy male, Avian breed chickens were housed in
batteries of cages from July to August 2004, and divided into two groups. The first group was submitted to a high
ambient temperature for one hour, daily, from the first to the 42nd day of age (Group ST). The second was kept at
a thermally confortable temperature (Group TN). Respiratory frequency and cloacal temperature were analyzed
weekly in ten birds from the ST group, before and after heat stress. In Group TN, these parameters were
assessed between the times of 12:00 and 13:00hrs. Delineation was done in Split-Plot in time. The effect of
ambient temperature was considered the plot, while the effect of age was taken as the split-plot. The data were
analyzed by the analysis of variance, and the means were compared by the Tukey test at 5%. The birds in STand
TN displayed increase in cloacal temperature with age. In Group TN, the respiratory frequency diminished with
age. The birds in ST had increased respiratory frequency and cloacal temperature after heat stress. Thus, the
body temperature increases with the chicken’s age, irrespective of the ambient temperature, and respiratory
frequency decreases with age for birds at thermoneutrality. Chickens for slaughter submitted to high cyclic
ambient temperature presented increase in respiratory frequency and cloacal temperature.