Analysis of Key Points in Winter Management Techniques for Live pigs

The arrival of winter brings some problems to pig farm management. Diarrhea has become an unavoidable and most headache-inducing problem on pig farms, and insulation work will become one of the most important tasks in pig farm management. But before many pig farms have fully solved the diarrhea problem in pigs, respiratory problems in pigs quietly arrive. Like diarrhea in pigs, in recent years pig respiratory diseases have become a very headache-inducing problem on pig farms, bringing major economic losses to the @#@227@#@ industry. Properly handling the issues of warmth and ventilation in pig farms is directly related to controlling diarrhea and respiratory syndrome, and is also the top priority of winter management on pig farms. This article discusses some views on how to control diarrhea and respiratory diseases in pigs in winter.

1. Keeping warm

In winter, cold weather is a great stress for pigs, especially young pigs. For newborn piglets, if the temperature difference between day and night exceeds 5°C, diarrhea may occur. Therefore, keeping warm is especially important for young pigs. But how to do a good job of insulation, such as how to properly handle the relationship between insulation and ventilation, also requires great attention. These issues are explained below:

The optimal temperature range for pigs: For newborn piglets, from the maternal environment of 38°C to outside the body, the temperature environment should be maintained at 32.5-34°C on the first day, then decreased by about 0.5°C per day, and reduced to about 25°C at weaning.

Methods and approaches for keeping warm

Reduce temperature loss: such as closing doors and windows, adding plastic sheeting over exercise areas, and plugging gaps to prevent drafts; make insulated boxes for piglets so they sleep inside them, and lay wooden floors, plastic boards, or add carpets where piglets sleep;

Increase heat sources: This is crucial for the cold winter. Specifically, it is divided into overall insulation and local insulation. Overall insulation should be determined according to each farm's specific situation, such as heating outdoor air by combustion and sending it into the pig house through hot air, or heating the entire pig house through insulation pipes or tunnels, or directly burning coke (or wood shavings) inside the pig house for heating. Local insulation means adding infrared heat lamps above the pigs' sleeping area or having them sleep on heated carpets;

Appropriately increase density: Except in farrowing houses, pigs at other stages can all use this method; nursery pig density 0.35 sq m, growing pig 0.65-0.7 sq m, adult pig 0.85-0.9 sq m;

Appropriately reduce space: such as adding a ceiling inside the pig house (using waterproof cloth or plastic).

2. How to properly handle the relationship between insulation and ventilation

For pigs, a suitable temperature environment is certainly very important, but having only a suitable temperature is far from enough. In a sense, a good air environment is even more important. When we keep pigs warm, we often unknowingly damage the air environment for pig growth. For example, sealing measures reduce the inflow of fresh air, combustion consumes oxygen in the pig house, increasing density increases the discharge of waste gases, and reducing space reduces the total amount of fresh air. All of these are unfavorable, or even harmful, to pigs. From a management perspective, insulation and ventilation are a pair of contradictions. Whether insulation or ventilation, both are crucial to pigs. All management measures on a pig farm should be considered and carried out closely around the physiological health of pigs. How to handle this pair of contradictions in management becomes the key to whether a pig farm succeeds. As the saying goes, "Of two benefits, choose the greater; of two harms, choose the lesser."

The purpose of ventilation is to improve the air quality in the pig house. For pigs, good air quality mainly refers to having enough oxygen in the air and fewer waste gases or harmful gases (such as carbon monoxide, carbon dioxide, hydrogen sulfide, ammonia, etc.). Harmful gases in pig houses are produced by the pigs themselves. To improve air quality, in addition to increasing the amount of fresh air, the content of harmful gases must first be reduced. In livestock houses, due to the respiration of high-density livestock and poultry, excreta, and the decomposition of organic matter during production, the composition of harmful gases is more complex and greater in quantity than in outside air. These harmful gases are mainly ammonia, carbon monoxide, and hydrogen sulfide.

Ammonia is mostly produced by the decomposition of organic matter (such as feces, urine, feed, bedding, etc.). When livestock remain in low concentrations of ammonia for a long time, their resistance to Mycoplasma and other infectious diseases is significantly weakened. Under the toxic effects of ammonia, the infection process of Bacillus anthracis, Escherichia coli, and pneumococcus is significantly accelerated. These cause livestock constitution to weaken, become sensitive to certain diseases, and significantly decrease feed intake, daily weight gain, and productivity.

Hydrogen sulfide mainly comes from the decomposition of sulfur-containing organic matter. When livestock and poultry eat feed rich in protein but suffer from indigestion, large amounts of hydrogen sulfide can be excreted from the intestinal tract. Hydrogen sulfide has a high specific gravity, and the closer to the ground, the greater its concentration. Livestock and poultry are prone to gastrointestinal diseases, cardiac weakness, etc., and grow slowly with low feed conversion rates.

(1) Methods and approaches to improve air quality

Eliminate harmful gases in livestock houses: ① remove feces promptly; ② pay attention to moisture prevention and insulation; ③ rationally organize ventilation and air exchange; ④ use superphosphate to reduce ammonia in the house, because superphosphate can absorb ammonia and form ammonium salts; ⑤ add sulfur powder to bedding to make the pH of feces lower than 7.0 and reduce ammonia production; ⑥ spread a layer of adsorbent materials such as activated carbon or quicklime on the ground, which can also eliminate odors in the air to varying degrees; ⑦ use equal parts of mugwort leaf, Atractylodes rhizome, Isatis leaf, garlic, and straw, in an appropriate amount, for fumigation, which can both inhibit and kill bacteria and drive out foul air in the house; ⑧ biological deodorization method, adding certain probiotics to feed to reduce ammonia in feces.

(2) Do a good job of ventilation and air exchange, and increase the supply of fresh air

Reduce oxygen consumption:

The ventilation system must be able to discharge the moisture exhaled by the pigs, excess heat, waste gases, odors and dust, and polluted air containing airborne pathogens out of the house, while also keeping the house free of drafts. Ventilation in a pig house uses fresh air to dilute the polluted air inside. After full mixing, what is discharged is the mixed polluted air. One important role of the ventilation system is to introduce fresh air.

While fresh air enters the house and polluted air is discharged outside, the pig herd should always be kept within a suitable temperature range. Achieving this is truly not easy. In summer and autumn, the outside temperature is high, and the north and south windows or rolling curtains of the pig house can all be fully opened. The amount of natural ventilation is large, and ventilation and insulation can be unified, or negative-pressure cooling ventilation can be used. But in winter and spring, ventilation and insulation often form a pair of contradictions. This contradiction is resolved by adjusting the air inlet and air inlet speed, as well as heating the introduced air or increasing the temperature inside the house.

Positions of air inlets and exhaust outlets. According to the ventilation principle inside a pig house, air inlets are generally expected to be parallel to the line below the ceiling or opened in the ceiling. The air inlet design can be adjustable in size. The exhaust outlet is designed opposite the air inlet (on the south side), 30-40 cm lower than the air inlet.

Positive-pressure ventilation. Fans can both expel air outward and push air inward; 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. To distribute fresh air evenly inside the house, the fan should be connected to an air delivery duct running lengthwise through the pig house. A small advantage of positive-pressure ventilation is that in cold weather the air is often heated. Positive-pressure ventilation avoids cold air forming drafts at the bottom of the pigs and other places. But positive-pressure ventilation also has some serious disadvantages, such as resistance in the ventilation duct, inability to discharge stale air promptly, and polluted air possibly being pushed into adjacent pens, making it difficult to form a "fresh air" zone.

Ventilation volume from minimum to maximum in all-in-all-out pig houses. In winter, when the nursery house is full of weaned piglets, the issue of ventilation volume must be considered. Because piglets use high-concentration feed and grow very quickly, their activity creates a lot of dust and ammonia. Especially when the weather becomes warm in early spring, a very large ventilation volume is needed after one month. In this case, the ratio of maximum ventilation to minimum ventilation is 32:1, sometimes even greater, rather than the usual 16:1 when raising pig herds of different ages or adult pig herds. A related problem is that in winter the ventilation volume for weaned piglets is very low. At this time, the fresh air entering the house does not have enough kinetic energy to mix with the hot air inside. Instead, the denser cold air settles to the ground, while the hot air rises to the roof. To solve this contradiction, use heated positive-pressure ventilation, heating the incoming air to about 30°C through a heat source device, sending it through a hot air delivery duct to the layer inside the house consistent with the piglets' activity plane, and then installing an exhaust fan 30-40 cm below the ceiling inside the house to extract and discharge the polluted air outside. In this way, the problems of ventilation and insulation are solved.

Fan selection. The ventilation system uses fan power or air vents or air pressure layers or natural wind to mix the air inside the pig house and the air outside in different proportions to form circulating airflow or natural wind airflow, providing fresh air. To avoid being affected by the external air environment, fan power is often used to achieve the goal. When selecting a fan, the following 5 main factors should be considered: fan type, ventilation capacity, overall ventilation efficiency, reliability and durability, and noise.

Natural ventilation. The pig houses we design should, when the outside temperature rises and ventilation and insulation are not in conflict, use natural ventilation as much as possible. Natural ventilation has no power cost and the best effect.

Control standards for harmful gases in pig houses. Ammonia, carbon dioxide, hydrogen sulfide, methane, and carbon monoxide are the main harmful gases affecting production performance and causing disease. Hydrogen sulfide and carbon monoxide can even directly cause pig death, while other gases only indirectly affect pig productivity and health. Therefore, it is required that inside pig houses NH3 <= 10 ppm, H2S <= 7 ppm, CO2 <= 1500 ppm.