There is a solution to the ventilation problem of raising chickens in summer.

In summer, many of our farmers are worried sick about the problem of ventilation. Either heat stress can not lower the temperature, or they do not have a good sense of propriety and excessive health. A cold stress causes colds and colds. In fact, these problems are mainly caused by too low or too high wind speed, wrong wind direction and excessive humidity. These reasons are not only caused by configuration, but also by improper operation.

Why are some henhouses 28 ℃ chickens all right? Why are there chicken coops 28 ℃ chickens with their mouths open?

  

The crux of the problem: the leeward speed of the chicken is too low and the somatosensory temperature of the chicken is high. When the house is 28 ℃, assuming that the relative humidity in the house is 70% and the wind speed is 2m/s, the somatosensory temperature of the chicken is 22: 23 ℃; when the wind speed is 1.5m/s, the somatosensory temperature of the chicken is 24: 25 ℃; the wind speed is 1m/s, and the somatosensory temperature of the chicken is 25.5-26 ℃.

  

Reason 1: some farms only consider the general high temperature in summer, ignoring the climate of high temperature and humidity, in order to save investment. The configuration of fan is less. In the hot and humid weather, the cooling efficiency of wet curtain is low, so we can only rely on increasing ventilation to reduce the somatosensory temperature of chickens.

  

Reason 2: the quality of the fan is poor, the performance is unstable, and the exhaust efficiency is low under high negative pressure. For example, for some fans, the 0pa static pressure exhaust capacity marked on the nameplate is 43000m3/h, but because of the blade shape and material, the strength is not enough, under-20pa negative pressure operation, the air exhaust capacity is only 30000m3/h, which is much lower than the general 37000m3/h data.

  

Reason 3: fan lack of maintenance, bearing wear, triangular conveyor belt relaxed or blocked by chicken feathers, not timely replacement and cleaning, the exhaust efficiency of the fan decreased. Or fan aging, not timely replacement.

  

Reason 4: wrong calculation and too little fan configuration. I have seen a large modern broiler farm, cascading cage, chicken house specification 100m*19m*4.2m~6m, vertical tunnel fan 24, aisle wind speed 3.1m/s, the wind speed in the cage 50cm is only 0.75m/s, the feeding effect is not very good in summer. If the farm is built in a dry climate in the northwest, the wet curtain can reduce the temperature in the house to 23-24 ℃, which is no problem in summer. However, in fact, the chicken farm is built in coastal areas, and the average humidity in summer is more than 80%. The evaporation and cooling efficiency of the wet curtain is low, which mainly depends on fan ventilation, and it is obvious that there are few fans.

  

* improvement methods: frequent maintenance, even if the bearing and triangle belt are replaced, chicken feathers are cleaned; fans with long service life and low exhaust efficiency are replaced; if the configuration is too little, increase the fan configuration, the configuration calculation should be based on the wind speed required for extreme high temperature and humidity weather.

Reason 5: the negative pressure is too high when opening the wet curtain. It leads to a strong wind ahead. The back suffocates and suffocates oxygen. Even if the temperature is not high, it still hurts the chicken. Especially adult chicken.

  

* improvement: increase the area of the front air inlet. Thus reducing the front wind speed. Increase the wind speed behind. Reduce the negative pressure.

  

Second, the feed intake of chickens in some areas does not increase, but decreases temporarily, and the weight of chickens in this area is on the low side. This phenomenon is generally found in chicken sheds raised in net beds.

  

Reason 1: the design wind speed is too high. The highest data of 2.5m/s is used in the design of ventilation configuration, and the air leakage compensation 0.25m/s is added, but the wind resistance effect of the bed frame is ignored, and the wind speed in the middle of the chicken coop will be greater than that on both sides, when the fan is fully open, it will cause the chicken leeward speed in the local area to reach more than 3m/s. When the chicken leeward speed is higher than 2.5m/s, the chicken feed intake will temporarily slightly decrease, but it will recover quickly; when the chicken leeward speed is higher than 3m/s, the feed intake will decrease significantly.

  

* improvement: install a manual switch on 10: 15% of the fan line as a backup, usually turn it off, turn it on in extremely hot and humid weather, or open when other fans fail.

  

Reason 2: improper grouping of fans, the last group of controlled fans are too many, open frequently, the wind speed will increase suddenly, and the wind speed varies greatly, which leads to the decrease of stress feed intake of chickens. For example, if a chicken house has 5 sidewall fans and 8 longitudinal tunnel fans, if a 5-stage ventilation controller is used, the sidewall fans are divided into two groups, and the longitudinal tunnel fans are divided into three groups (2-2-4 or 2-3-3), the wind speed drop of 0.8~1m/s will inevitably occur.

  

* improvement method: replace the environmental controller, increase the grouping of fans, and the maximum drop of wind speed does not exceed 0.5m/s.

  

Reason 3: there is no deflector in the air inlet of the wet curtain on both sides, and the wind speed is in 3~5m/s. Such a high wind speed blows directly to the chicken, causing stress.

  

* improvement method: equipped with thermal insulation guide plate, summer diversion, so that the air flow oblique upward, not directly blowing chicken, and heat preservation in winter.

  

Third, there is a sudden increase in the death of older chickens, and the time of death mainly occurs at night, mainly the heavier chickens. The above phenomenon will occur when the heat stress index of the environment is higher than 165, and a large number of deaths will occur when the heat stress index is greater than 170. There are special articles on heat stress, so I won't say much here.

  

Reason 1: the more common situation is that the humidity in the house is too high, the wind speed is too low, and the temperature is too high. the most common operation error leading to this situation is to turn off the fan or reduce the number of fans when spray cooling.

  

* improvement: normal ventilation must be maintained during spray cooling; in hot and humid weather, ventilation should be slightly increased and backup fans should be turned on.

  

Reason 2: after the power outage in summer, the remedial measures are not timely. Even if there is a backup generator, it can not be started in time because it has not been used for a long time.

  

* improvement: no matter whether there is a power outage or not, the standby generator set will start up and operate once a month.

  

Fourth, it is difficult to cool down in the local area, and the chickens leave the area automatically. This phenomenon often occurs in the flat chicken house, especially in the flat chicken house on the ground, and it often appears in the middle of the chicken house and the waist rib area on both sides.

  

Cause: this phenomenon is mostly caused by improper operation, the cooling wet curtain is installed on both sides of the head, the negative pressure of the air inlet of the wet curtain is too low or too high, and the air flow cover is uneven.

  

* improvement method: open the size of the wet curtain according to the width of the chicken house and the number of fans. If you do not know how to operate, hang a recording tape every 1.5m between the left and right wet curtain air inlets and on both sides of the chicken house. Adjust the size of the air inlet by observing the tape flutter. It is best to install a type 24 flat mixing fan on both sides of the chicken house every 15 meters or so to force uniform air circulation.

Fifth, the temperature difference between the tail end and the head end is more than 3 ℃, and some high-density caged chicken sheds may even exceed 5 ℃.

  

Reason 1: the chicken coop is too long. The chicken sheds of large-scale chicken farms are getting longer and longer, with many broiler sheds of 120 meters or even 150 meters, and cages with more than 80 meters and 100 meters. In the process of the cold air coming from the head end to the tail end, the heat generated by the chicken continues to increase the temperature of the flowing air, resulting in the temperature of the tail end higher than that of the head end. The longer the chicken coop, the greater the temperature difference.

  

* improvement method 1: move the 15-20% wet curtain from the head end to the middle of the chicken house, so that the back wind speed of the first half of the chicken is 2m/s, and the back wind speed of the second half is 2.5m/s, which can reduce the temperature difference and keep the somatosensory temperature of the chicken basically the same. This method must be calculated accurately, if the wet curtain area in the middle is too large, the effect will be counterproductive.

  

* improvement method 2: for chicken sheds more than 120 meters long, you can try to install wet curtains on the side walls in the middle of the henhouses and fans at both ends of the henhouses, but the investment in such fans and wet curtains should be doubled.

  

Reason 2: the chicken coop is not strictly closed. The main reason is that the sealing of air inlet window, daylighting window, eave and wall, head and tail door and manure outlet is too poor, which leads to the wind speed in the house is lower than the design wind speed or the difference between the front and back wind speed is too big.

  

* improvement method: improve the tightness of the chicken house, especially the manure outlet at the tail end can be sealed with 3mm thick rubber soft plate, nailed to the top, and can be opened and closed automatically with the entry and exit of the manure remover.

  

Reason 3: the ventilation time is too long. In summer, if the wind speed is too low, it will make the ventilation time of the chicken house too long, thus increasing the heat accumulation of the flowing air, resulting in excessive temperature difference. Generally speaking, the ventilation time of flat house is not more than 60 seconds, and that of cage house is not more than 45 seconds.

  

* improvement methods: increase the wind speed in the house, flat 2~2.5m/s, stepped cage 2.3~2.7m/s, cascading cage 3~4m/s.

    

Sixth, open the wet curtain pump, but the cooling effect is not obvious, only the chicken coop head within 10-15 meters feel cool, and then it is difficult to lower the temperature.

  

Reason 1: high temperature and humidity weather, such as the weather exposed to the sun after a thunderstorm, the outdoor relative humidity is more than 80%, evaporation is difficult, and the cooling effect is not obvious.

  

* improvement method: change the water source of the spray line from normal temperature water to low temperature well water, maintain normal ventilation, and adopt water cooling to force cooling. When the outdoor relative humidity exceeds 80%, the relative humidity in the chicken house is also very high, and the spray has little effect on the relative humidity in the house.

  

Reason 2: the nozzle is blocked and needs to be cleaned.

  

* improvement method: add recoil device and flush it regularly.

  

Reason 3: the wet curtain is blocked by dust, chicken feathers, leaves and so on.

  

* improvement method: install protective net and replace the wet curtain paper every 4 ~ 6 years.