On the Management of Pigs in Winter

With the advent of winter, the management of pig farms will bring some problems. Diarrhea has become an unavoidable and headache problem in pig farms, and heat preservation will become one of the most important tasks in pig farm management. However, before the problem of pig diarrhea has been completely solved in many pig farms, the respiratory problems of pigs have come quietly. Like pig diarrhea, pig respiratory disease has become a very headache problem in pig farms in recent years, which has brought great economic losses to the industry. Dealing with the problems of warmth and ventilation in pig farms is directly related to the control of diarrhea and respiratory syndrome, and it is also the top priority of pig farm management in winter. This paper gives some views on how to control diarrhea and respiratory diseases in pigs in winter.

1. Keep warm

In winter, cold weather is a great stress for pigs, especially young piglets. For newborn piglets, diarrhea may occur when the temperature difference between day and night is more than 5 ℃. Therefore, heat preservation is very important for young pigs. However, how to do a good job of thermal insulation, such as how to deal with the relationship between thermal insulation and ventilation, is also very fastidious, the following issues are described as follows:

The optimum temperature range of pigs: for newborn piglets, from the maternal 38 ℃ environment to in vitro, the temperature should be maintained at 32.5-34 ℃ on the first day, and then decreased by about 0.5 ℃ per day to about 25 ℃ after weaning.

Methods and ways of heat preservation

Reduce temperature loss: such as closing doors and windows, sealing plastic sheets in playgrounds, etc., plugging loopholes to prevent thieves; making incubators for piglets to sleep in incubators, laying wooden floors or plastic panels or adding carpets in places where piglets sleep

Increase heat source: it is very important for cold winter, which is divided into whole heat preservation and local heat preservation. The whole heat preservation should be decided according to their specific conditions, such as heating the pig house through hot air after outdoor combustion, heating the pig house through insulation pipes or tunnels, or directly burning coke (or sawdust) in the pig house. Local heat preservation is to add an infrared insulation lamp above the pig's sleeping area or sleep on a heated carpet.

Appropriate increase in density: this method can be used for pigs at all stages except in the delivery room; the density of nursery pigs is 0.35 square meters, that of medium pigs is 0.65 square meters, and that of big pigs is 0.85 square meters.

Reduce space appropriately: for example, add a roof in a pigsty (with tarpaulins or plastic).

2. How to deal with the relationship between heat preservation and ventilation

For pigs, the appropriate temperature environment is very important, but it is far from enough to have a suitable temperature. In a sense, a good air environment is more important. When we keep pigs warm, we often unwittingly destroy the air environment in which pigs grow. For example, sealing measures reduce the inflow of fresh air, burn the oxygen in the pigsty, increase the density, increase the exhaust gas emission, reduce the space and reduce the total amount of fresh air, all of which are disadvantageous or even harmful to pigs. From a management point of view, heat preservation and ventilation are a pair of contradictions, whether it is good heat preservation or ventilation is very important for pigs. All measures for the management of pig farms should be closely focused on the physiological health of pigs. How to deal with this contradiction in management has become the key to the success of pig farms. As the saying goes, "choose the weight of the two benefits and the lesser of the two evils."

The purpose of ventilation is to improve the air quality of pig sheds. For pigs, good air quality mainly means that there is enough oxygen and less exhaust gas or harmful gases (such as carbon monoxide, carbon dioxide, hydrogen sulfide, ammonia, etc.) in the air. The harmful gas in the pig house is produced by the pig itself. in order to improve the air quality, it is necessary to reduce the content of harmful gas in addition to increasing the amount of fresh air. Due to the respiration and excretion of high-density livestock and poultry and the decomposition of organic matter in the production process, the composition of harmful gases in the barn is more complex and larger than that in the outside air. These harmful gases are mainly ammonia, carbon monoxide and hydrogen sulfide.

Ammonia is mostly decomposed from organic matter (such as feces, urine, feed, bedding grass, etc.). When livestock were exposed to low concentration of ammonia for a long time, their resistance to mycoplasma and other infectious diseases decreased significantly. Under the toxic effect of ammonia, the infection process of Bacillus anthracis, Escherichia coli and pneumococcus was significantly accelerated. These lead to the weakening of livestock physique, sensitivity to some diseases, and a significant decrease in feed intake, daily gain and productivity.

Hydrogen sulfide is mainly decomposed by sulfur-containing organic compounds. When livestock and poultry eat protein-rich feed and indigestion, a large amount of hydrogen sulfide can be excreted from the intestines. The higher the proportion of hydrogen sulfide, the closer to the ground, the higher the concentration. Livestock and poultry are prone to gastrointestinal disease, heart weakness, slow growth and low feed conversion rate.

(1) methods and ways to improve air quality.

Eliminate harmful gases in the barn: ① timely eliminate faeces; ② pay attention to moistureproof and heat preservation; ③ reasonably organize ventilation and ventilation; ④ uses calcium superphosphate to reduce ammonia in the house, because calcium superphosphate can absorb ammonia and produce ammonium salt; ⑤ adds sulfur powder to the cushion to make the pH value of feces lower than 7.0. reduce the production of ammonia. ⑥ sprinkles a layer of activated carbon, quicklime and other adsorptive materials on the ground, which can also eliminate the odor in the air in varying degrees; ⑦ fumigation with moxa leaves, atractylodes, green leaves, garlic and straw, with moderate dosage, can not only inhibit and kill bacteria, but also drive away the foul air in the house; ⑧ biological deodorization method, adding some probiotics in the feed to reduce the ammonia in the feces.

(2) do a good job in ventilation and increase the supply of fresh air

Reduce oxygen consumption:

The ventilation system must be able to expel the exhaled moisture, excess heat, exhaust gas, odor and dust, and foul gas containing floating pathogens out of the house, while keeping the house free of thieves. The ventilation of the pig house is to dilute the dirty air with fresh air. After fully mixing, the dirty air is discharged after mixing. One of the important functions of ventilation system is to introduce fresh air.

When fresh air enters the house and foul air is discharged out of the house, pigs should be kept in a suitable temperature range all the time. It is really not easy to do this. When the external temperature is high in summer and autumn, the north and south windows or shutters of the pig house can all be opened, and the natural ventilation volume is large, so ventilation and heat preservation can be unified, or negative pressure cooling ventilation, while ventilation and heat preservation in winter and spring often form a pair of contradictions. This contradiction can be solved by adjusting the air inlet and air intake speed, heating the imported air or increasing the temperature in the house.

The position of air inlet and exhaust outlet. According to the ventilation principle in the piggery, the air inlet is generally expected to be parallel to the ceiling or open on the ceiling, the air inlet is designed to be adjustable, and the exhaust air outlet is designed on the opposite side (south) of the air inlet, which is lower 30~40cm than the air inlet.

Positive pressure ventilation. The fan can not only discharge the air out, but also press the air in, the latter is called positive pressure ventilation, that is, the air pressure inside the pig house is slightly higher than the average air pressure outside the house. In order to distribute fresh air evenly in the house, the fan should be connected with the air conveyor through the ventilation duct of the pig house. A small advantage of positive pressure ventilation is that cold weather often heats the air, positive pressure ventilation avoids the formation of cold air in places such as the bottom of the pig. However, positive pressure ventilation also has some serious shortcomings, such as the resistance of the ventilation duct, the turbid air can not be discharged in time, and the dirty air may be squeezed into the pigsty next to it, so it is difficult to form a "fresh air" area.

All in and out of the pigsty from minimum to maximum ventilation. In winter, when the nursery is full of broken piglets, the amount of ventilation must be considered. Because piglets use high feed concentration, fast-growing piglets are dusty and ammonia, especially when the weather is warm in early spring, they need a lot of ventilation a month later. In this case, the ratio of maximum to minimum ventilation is 32:1, sometimes greater, rather than 16:1 when pigs of different ages or adults are usually raised. The related problem is that the ventilation rate of weaned piglets in winter is very low. At this point, the fresh air entering the house does not have enough kinetic energy to mix with the hot air in the house. instead, the denser cold air settles to the ground and the hot air rises to the roof. In order to solve this contradiction, heating positive pressure ventilation was used to heat the air in the house to about 30 ℃ through the heat source, and then sent to the inner floor of the house consistent with the moving plane of the piglets through the hot air conveying pipe, and then an exhaust fan was installed at the 30~40cm under the roof of the house, which drained the foul air out of the house, thus solving the problem of ventilation and heat preservation.

Fan selection. The ventilation system is through the fan power or vent or air pressure layer or natural wind to mix the air inside and outside the piggery in different proportions to form circulating air or natural air flow to provide fresh air. In order not to be affected by the external air environment, fan power is often used to achieve the goal. The following five main factors should be considered when selecting fan: type of fan, ventilation capacity, comprehensive ventilation efficiency, reliability and durability, and noise.

Natural ventilation, we designed pig houses to make use of external temperature rise, in ventilation and heat preservation is not contradictory, as far as possible natural ventilation. Natural ventilation has no power cost and the effect is the best.

Standard for harmful gas control in piggery. Ammonia, carbon dioxide, hydrogen sulfide, methane and carbon monoxide are the main harmful gases that affect production performance and cause epidemic diseases. Hydrogen sulfide and carbon monoxide can even cause the death of pigs directly, while other gases can only indirectly affect the productivity and health of pigs, so NH3 ≤ 10ppm H2S ≤ 7ppm CO2 ≤ 1500ppm is required in the pigsty.