Applying Direct Evaporative Cooling System for Controlling Environmental Conditions in Rabbit Houses

Abstract

Heat stress is a major problem that faces rabbit's breeders. This problem adversely affects rabbit's growth and reduces the resistance to diseases. The present research was carried out to apply and evaluate the performance of a direct evaporative pad cooling system in rabbit houses to control environmental conditions. The direct evaporative pad cooling system performance was studied as a function of change in pad thickness (10 and 15 cm), water flow rate (3, 5 and 7 L/min.m 2 ) and rabbit stocking density with an approximate average (0.5 and 1.0 rabbit/m 2 ). Performance evaluation of the evaporative pad cooling system was carried out in terms of temperature reduction, cooling efficiency, temperature-humidity index, daily body weight gain and mortality ratio. The experimental results clarified that values of temperature reduction (7.3 and 6.8 o C), cooling efficiency (94.92 and 90.91 %), temperature-humidity index (26.30 and 27.40 o C), daily body weight gain (38.80 and 38 g/rabbit/day) and mortality ratio (0.2 and 0.4 %) are in the optimal limits under conditions of 15 cm pad thickness and 5 L/min.m 2 water flow rate for rabbit stocking densities of 0.5 and 1.0 rabbit/m 2 , respectively. INTRODUCTION he Egyptian people like so many foods made of rabbits; therefore, rabbit's projects are economically important. Rabbits are often breeding in cages or batteries. The clearest limitation of rabbit production in hot climate regions is this species susceptibility to heat stress. Heat stress occurs mainly when animals are exposed to high direct and indirect solar radiation, high humidity, high ambient temperatures and low wind speed. Willmer et al. (2000) defined heat stress as a stress caused by an extensive range of environmental conditions that motivate physiological strain state within the animal's body, meaning that animals are unable to regulate their thermal balance in a negative way.