The Design Of A New Ventilation Mode And Its Effect On The Production Performance Of A Farrowing House In Hunan Province

Zhuzhou City of Hunan province belongs to the continental subtropical monsoon humid climate,with high temperature and humidity in summer.Aiming at a series of problems such as high temperature in summer and poor air quality in winter in the fully enclosed pigsty in Zhuzhou area,a new ventilation mode design and its impact on the production performance of the pigsty delivery house were carried out.On the basis of theoretical research and calculation,a new ventilation mode design and pig farm construction were carried out for12000 sows of a group in Hunan Province,and the thermal environment and air quality environment of the large pig farm were tested and analyzed with the method of field measurement;the production performance of the pig farm was continuously followed for one year,and the sows and suckling piglets in the pig farm were also born Production performance analysis.The results are as follows:（1）When the new delivery house is ventilated in winter,the air inlet window of the attic is closed,and the fresh air outside the house enters the pig house from the adjustable air inlet windows on both sides of the gutter.The adjustable air inlet guide plate guides the cold air outside the house to form a clothing jet along the roof of the pig house,and exchanges heat with the hot air on the top of the pig house in the process of flow.The temperature gradually rises and falls to the active area of the pig group,so that the pig group does not Cold stress;In summer ventilation,the side wall air inlet window is closed,and the outdoor hot air enters the attic area from the attic air inlet for pre cooling,then enters the room through the wet curtain for cooling,and then exits through the fan.According to the climatic conditions in Chaling area of Hunan Province,the theoretical calculation of ventilation parameters of pigsty is used to obtain the minimum ventilation capacity of experimental pigsty in winter and 1348 m3/h in summer.There are 12 side wall air inlet windows,and the total pressure drop of pigsty in summer is 20 Pa.two 24’variable speed FRP fans,two 36’FRP fans and three 51’FRP fans are provided.（2）Based on the field test of pig farm,the hot environment and air quality environment in the delivery shed in summer were analyzed.The results showed that the temperature in the shed was controlled below 30.0℃,but the temperature distribution in the front and back of the shed was uneven,and the maximum temperature difference in the front and back of the shed was 2.0℃in the hottest time.The index of temperature and humidity index（THI）was maintained at about 66-72 during the test,all of which were in the state of no heat stress.The range of wind speed in the 0.5m height pig lying area is 0.8～1.5m/s.The wind speed is good.The length and width of the pig house have no significant influence on the wind speed.The wind speed will increase with the increase of the horizontal height.The results showed that the distribution of NH₃ and CO₂ concentration in the longitudinal ventilation pig house was similar in winter,which were lower than the national standard.The concentration of NH₃ and CO₂ in the room from the wet curtain to the fan gradually increased.The concentration of NH₃and CO₂in the lying area of pigs was higher than that in the breathing area of people.The length and height of the shed had a significant effect on the concentration of NH₃ and CO₂（P<0.01）,while the width of the shed had no significant effect on the concentration of NH₃ and CO₂（P>0.05）.During the test period,the relative ventilation efficiency and the overall ventilation efficiency of each measuring point are greater than 1,and the ventilation capacity is excellent.The concentrations of PM2.5 and PM10 in the shed were lower than the requirements of national standards.The length,width and height of the shed had no significant effect on the concentrations of PM2.5 and PM10（P>0.05）.（3）Compared with the traditional model delivery house,the new model delivery house has lower mortality rate of suckling piglets（5.25%<6.59%）,and has higher weaning weight（6.55>6.11）and weaning number（10.81>10.04）;the estrus rate within 7 days in the new model pig farm is significantly higher than that in the traditional model pig farm（88.82%>83.42）;the breeding pregnancy rate of the new model pig farm is significantly higher than that in the traditional model pig farm（88.51%>84.8）.