| The ambient temperature,humidity,wind speed and solar radiant are constitute the thermal environmental for livestock.However,the thermal environment plays an important role in limiting the health of animals and the production of feedlot.It is so meaningful to know the disadvantage of heat stress and to find out the right evaporation cooling methods,which is beneficial for heat stress relief and improving the production performance in feedlots.This paper was to determine the effect of spraying and ventilation on beef cattle barn in South of China.Two same barns were chosen,one was treatment installed spraying ventilation cooling system,the other was control with ceiling system.The cooling system was open from 08:00 to 19:00 for 6 days.Weather data and physiological indices were collected at 10:00 14:00 and 18:00 respectively during experiment.The results showed that the ambient temperature of treatment was 1.1,1.75 and 1.32 lower than control(?),while its wind speed was higher than that in control(p<0.05).There were no significant difference between two groups in temperature-humidity indices.The density of Dinitrogen oxide,Ammonia and Carbon monoxide in control were 3.8%,8.7%and 6.7%higher than treatment.At 10:00 14:00 and 18:00,the respiration rate of treatment was 13,21.4 and 20.5 breathe per minute lower than the control,while the rectal temperature and skin temperature of treatment were 0.33,0.39,0.28,1.76,2.37,and 0.68(?)lower than the control respectively.In conclusion,the system of spraying ventilation can decrease the ambient temperature,improve the air quality of barn,decreased the respiration rate,rectal temperature and surface temperature significantly,relieve the heat stress of beef cattle and increase economic profit of beef cattle production.The aim of this paper was to investigate the effect of the system of cooling fan-duct on beef cattle barn in South of China.Two same barns were selected randomly,one was the control installed with ceiling fan,the other was treatment installed with cooling fan-duct.Ten steers were chosen in each barn.All data were measured at 08:00 14:00 and 18:00 for 7 days.The results showed that this system of cooling fan-duct could increase the wind speed significant(p<0.05),decrease the ambient temperature(p<0.01).The respiration rate,rectal temperature and skin temperature of treatment were 8.8 and 14.4 breathe per minute,0.38 and 0.46,1.66 and 1.83(?)lower than the control.The relative humidity,the concentration of NH3 and CO2 in the treatment barn were 30.21%,7.0%and 14.44%higher than the control barn,but the air quality in the treatment still can meet the requirement of relative industry standards.In conclusion,the system of cooling fan-duct can decrease the ambient temperature,relieve the heat stress of beef cattle barn.This system of cooling fan-duct should be advanced installed and used in beef cattle in South.The subject of this paper was to investigate the physiological effect of cooling head on beef cattle and the physiological response in the following days.Eight healthy Simmentals were divided into two groups(treatment and control).Treatment was offered ten repeated cooling cycles by 20-s wetting followed by 10-min forced airflow and control group received no cooling.All of the measurement including weather data,respiration rate,rectal temperature and skin temperature were performed every two consecutive cooling cycles.The experiment I was undertaken from 12:00 to 15:00,While the experiment ? was undertaken from 12:00 to 15:00 and from 17:00 to 19:00.Furthermore,all data were collected in 06:00,07:00,08:00,09:00 and 10:00 if the head cooling occurred in the former nights(17:00-19:00).The results showed that temperature-humidity index in the experiment I was higher than 88,it indicated that beef cattle were subjected to seriously heat stress.The respiration rate in treatment decreased rapidly and was lower than that in control significantly and the greatest reduction was 23.4 breath per minute by ten cooling cycles.In the experiment II,the THI was lower than 62,which suggested animals were not in the heat stress.The respiration rate decreased rapidly,the greatest reduction was 21.6 breath per minute in the treatment.In the control,the respiration rate increased gradually and it was higher than treatment significantly(p<0.01).There were no significant difference between control and treatment in both experiment I and II of rectal temperature.The reduction in mean Ts produced by ten cooling cycles was 1.24 to 1.85? in the treatment in the heat stress.While under the no heat stress environment,the skin temperature of beef cattle in treatment kept stable and it in control increased and exceeded treatment significantly.The rectal temperature of beef cattle,which were subjected to head cooling in the former night,maintained at lower level and its respiration rate and skin temperature increased slower than the control.In conclusion,cooling head decreased the respiration rate and Ts of beef cattle,which was useful for relief of heat stress.Meanwhile,cooling head in the former night can decrease the rectal temperature and respiration,which was beneficial for animal to face high temperature in the following days. |
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