EFFECT OF EVAPORATIVE COOLING SYSTEM ON MICROCLIMATIC CIRCUMSTANCES OF COMMERCIAL CLOSED LAYING-HENS HOUSE UNDER DELTA-ZONE CLIMATIC CONDITIONS

Abstract

High temperature gradients can markedly affect laying hen's growth development, productivity, health and welfare of the birds. This research work was conducted to investigate the feasibility of using direct evaporative cooling to improve the indoor air conditions in a laying-hens house. In this present study trail, a laying-hens house of 460 m2 floor surface area was tested under climatic conditions of eastern area of coastal Delta, Egypt (latitude angle of 31.05oN, longitude angle of 31.37oE, and mean altitude above sea level of 14 m). Experiments were performed through three summer months of 2014 (from June to August) for laying-hens chickens at 150 days of age. Three different water flow rates (60, 70 and 80 l/min) were examined during the experimental work to determine the best one can be compensated the high air temperature occurred inside the housing. In order to achieve that, different measurements were accomplished in a commercial closed house of laying hens equipped with a complete evaporative cooling system (fan-pad system). Cooling effect (CE), cooling efficiency (η), temperature humidity index (THI), vapor pressure deficit (VPD), rate of heat energy removal from the laying hen's house (Q), total amount of moisture addition to the saturated air after cooling by evaporative process (W) and both of bird's body weight and production egg rate were computed during the experimental period. Experimental data revealed that the evaporative cooling system was able and adequate to keep and maintain the indoor air temperature of laying hens housing at desired level. The obtained results also clarified that the daily average cooling efficiency during June, July and August, was determined as 77.4%, 75.6% and 79.5%, respectively. Accordingly, the indoor dry- bulb temperature lowered between 7.1 - 8.5 °C with 30 – 40% rise in air relative humidity.