Precautions for ventilation management in pigstys

The ventilation methods currently used in most small and medium-sized pig farms can be divided into three types: roof ventilation, horizontal ventilation, and vertical ventilation. The author will introduce them separately below.

Roof ventilation. Roof ventilation refers to the use of density differences between different gases without the need for mechanical equipment, which allows the air inside the pigsty to flow up and down, thereby allowing the exhaust gas inside the pigsty to be discharged from above the roof in a timely manner. Roof ventilation can greatly reduce the concentration of exhaust gases inside the pigsty, ensuring fresh air and reducing the incidence of respiratory diseases; For pig houses that use underfloor ventilation windows and manure leakage floors, roof ventilation allows fresh and cool air from the outside to enter the pig body through the underfloor ventilation windows, taking away the heat and exhaust gases emitted by the pigs, which can have a significant cooling effect, especially after washing the pigsty in summer. Roof ventilation can be achieved by opening windows on the roof, installing unpowered fans on the roof, or installing roof fans.

Horizontal ventilation. Horizontal ventilation is generally natural ventilation or installing fans on the wall, mainly used for ventilation of open and semi open pigstys. To ensure smooth ventilation of the pigsty, it is necessary to fully consider the site selection, layout and direction of the pigsty, as well as the design of the pigsty. It is best to make the pigsty face perpendicular to the local main wind direction, so as to maximize the use of lateral ventilation. The air inlet for horizontal ventilation is generally composed of glass windows and rolling shutters. When installing rolling shutters, there should be an overlap of about 8 centimeters between the rolling shutters and the side wall to prevent thieves from entering; At the same time, fly nets should be installed on the inside of the roller shutter to prevent flies, mice, and other insects from entering to ensure biological safety; It is best to open the roller shutter from top to bottom to allow exhaust gas to be discharged from the top of the shutter, balancing ventilation and insulation.

Vertical ventilation. Vertical ventilation usually adopts mechanical ventilation, which is divided into two types: positive pressure vertical ventilation and negative pressure vertical ventilation. Generally speaking, positive pressure longitudinal ventilation is mainly used in pig houses with poor airtightness; Negative pressure vertical ventilation is used in pig houses with good airtightness. The air inside the house is forcibly extracted by a fan, forming negative pressure, allowing the outside air to enter the house through the air inlet under atmospheric pressure. During ventilation, a certain distance (usually about 1.5 meters) should be reserved between the fan and the pig to avoid adverse effects on the pig due to excessive wind speed near the inlet. The length of the longitudinally ventilated pigsty should not exceed 60 meters, otherwise the ventilation effect will deteriorate.

Control standards for ventilation management

The ventilation of pig houses usually takes the ventilation rate as the standard. The ventilation rate of a pigsty refers to the amount of fresh air entering or polluted air discharged per unit time, usually measured in cubic meters per hour. In actual production, it is often expressed as the required ventilation rate per head or kilogram of body weight, and the ventilation rate of the pigsty is determined based on the ventilation parameters.

In addition, the ventilation rate of the pigsty can also be determined based on the number of air changes during production. The number of air changes refers to the volume of fresh air exchanged within one hour being a multiple of the volume of the pigsty. Generally speaking, ventilation should be maintained between 3-4 times, and generally not more than 5 times. Of course, this representation method is relatively rough because it does not take into account factors such as pig species, age, feeding density, and feeding management methods.

Air hygiene quality requirements

The harmful components in the air of pig houses mainly include ammonia, hydrogen sulfide, carbon dioxide, and dust; Among them, ammonia and hydrogen sulfide have the greatest impact on the production performance and health of pigs. To ensure the normal growth performance of animals, it is necessary to control the concentration of these harmful gases through reasonable ventilation, so that the air hygiene quality of pig houses meets the requirements.

The influencing factors of ventilation

The influencing factors of ventilation in pigstys include: the location of the pigsty, the surrounding environment of the pigsty, and whether the pigsty is located at the upper or lower air outlet; Is the direction of the air inlet of the pigsty consistent with the local main wind direction; Whether the layout, direction, and spacing between different pigstys of the pigsty reach 2 meters; Is the structure of the pigsty open, semi open, or closed, as well as the length, span, and internal structure of the pigsty; Is the window opening method of the pigsty sliding or embedded, as well as the effective area and height of the window; Is there any shelter around the pigsty? When the wind encounters resistance, it will change direction and the wind speed will decrease. The more shelter there is, the smaller the ventilation volume.