AGE-DEPENDENT CHANGES IN DIURNAL THERMOREGULATORY RESPONSES OF RABBITS DURING THE EARLY-RAINY SEASON

Abstract

The study investigated the effect of age on diurnal thermoregulatory responses in rectal (RT) and ear surface temperatures (ET) of rabbits during the early-rainy season. Seventeen apparently healthy rabbits were divided into three groups of 5 weaners, 6 growers and 6 adults. Physiologic parameters
of RT and ET of the rabbits were recorded concurrently with thermal environmental parameters of dry-bulb (DBT) and wet-bulb readings every three hours, at 07:00, 10:00, 13:00, 16:00 and 19:00 h, once per week for three weeks using standard procedures. Result revealed that RT and ET were higher in adult compared to weaner or grower rabbits. The RT was higher in adult than weaner rabbits at 13:00, 16:00 and 19:00 h. While, the ET was higher in adult than the weaner rabbits at 07:00 h (33.53 ± 0.39 ˚C vs 31.91 ± 0.39 ˚C). However, there was no significant (P > 0.05) difference in physiological parameters between the weaner and grower rabbits. Thermal environmental parameters of DBT positively correlated with ET in all age groups of rabbits (Weaners r = 0656, P < 0.01; Growers r = 0.584, P < 0.01; Adults r = 0.642, P < 0.01). It was concluded that there was agedependent effect on diurnal thermoregulatory responses of rabbits and prevailing relative humidity negatively impacted on the heat dissipation. It is therefore recommended that adequate ventilation should be provided in rabbit house to reduce the negative impact of high relative humidity on heat dissipation ability of rabbits during the early-rainy season.