Study On Environmental Characteristics Of Beef Cattle Shed In Southern Region

The open shed is widely used in beef cattle production in the southern region because it designed to be simple and low cast. But, there is not environmental design code about construction of open shed, and lack of research report about environmental determination and evaluation about it. In order to provide evidence for construction and environmental control, this study on three kinds of open shed determinated the environmental parameters, tried to understand and evaluate the environmental characteristics.Part1:In order to understand the environmental characteristics of the open ridge shed with coconut trees overshadowing in the tropical, the determination of temperature, relative humidity, wind velocity, and PM10index in the beef cattle shed were carried out in Zhanjiang. The result indicated:the temperature and relative humidity were almost the same inside and outside the shed. The ventilation rate of the shed met and exceeded the requirement of the maximal ventilation rate. The concentration of PM10in the shed was better than the standard of environmental sanitation. The THI ranged from78to85, and the beef cattle were in heat stress. The THVI which considered the influence of wind ranged from25℃to30.5℃. At14:00and19:00of sunny days, the wind velocity was between0.95m/s and1.30m/s. The wind reduced the impact of high temperature evidently. The temperatures between the inside and outside roof surface during the testing period were all smaller than1癈therefore, the ability of heat insulation was not strong. The highest temperature of the inside roof was60.8℃, and the temperature in the shed at the same time was only33.4℃. The main part of the environmental control was the natural ventilation of the shed.Part2:In order to understand the environmental characteristics of the belfried open ridge shed, the determination of temperature, relative humidity, wind velocity, PM10, and NH3index in the beef cattle shed were carried out in Fengyang. The result indicated:In the summer, the temperature and relative humidity were almost the same inside and outside the shed. The ventilation rate of the shed met and exceeded the requirement of the maximal ventilation rate. The concentration of PMIO in the shed was better than the standard of environmental sanitation. The THI ranged from78to87, and the beef cattle were in heat stress. The THVI which considered the influence of wind ranged was from25.1℃to32.2℃. The wind reduced the impact of high temperature evidently. The temperatures between the inside and outside roof surface during the testing period were all smaller than1.2℃, therefore, the ability of heat insulation was not strong. The highest temperature of the inside roof was48.3℃, and the temperature in the shed at the same time was only33.1℃. The main part of the environmental control was the natural ventilation of the shed. It is advantaged to make the roof higher and sent a belfried shed. In the winter, the temperature inside the shed was from-1℃to7.5℃, and from-3℃to5.5℃outside the shed. The temperatures between the inside and outside were smaller than2℃. The wind velocity was between0.2m/s and0.4m/s. The relative humidity inside the shed was higher than outside, exceeded the standard of environmental sanitation. The concentration of NH3in the shed was better than the standard of environmental sanitation. The shed surrounded by plastic film is unnecessarily in winter.Part3:In order to understand the environmental characteristics and heat insulation performance of the open ridge shed with insulating layer, the determination of temperature, relative humidity, wind velocity, and PM1O index in the beef cattle shed were carried out in Lingbi. The thermal resistance value, decay rate, and delay time of the roof were calculated and compared with reference value. The result indicated:In summer, the temperature of shed ranged from23.0℃to29.5℃, but the THVI was from23.3℃to26.8℃, dropped by3℃. The wind velocity reduced the impact of high temperature evidently. The ventilation rate of the shed met and exceeded the requirement of the maximal ventilation rate. In winter, the temperature inside the shed was from-1.3℃to9.7℃. The temperatures between the inside and outside of the shed were smaller than1℃. The relative humidity inside the shed was from55%to85%. The concentration of PM1O in the shed was better than the standard of environmental sanitation. The highest temperature of the surface outside roof was60℃,19℃higher than the inside surface in summer. The lowest temperature of the surface outside roof was-12.3℃, and the temperature inside at the same time was-1℃in winter. The thermal resistance value was0.372m2-k/W in winter, and0.411m2·k/W in summer. The decay rate and delay time were4.3and0.2h. The insulating layer stopped radiant heat partly. The temperature in the shed was reduced. It is beneficial for heatstroke prevention.