Ammonia control measures in pig houses
With the continuous improvement of livestock production scale and intensification, the ammonia produced by livestock and poultry and their wastes is increasing day by day. A farm with an annual output of 100,000 pigs emits 159 kg of ammonia per hour into the atmosphere. Not only affects the normal human production and life, but also harms the health of livestock and poultry, reducing production performance. As early as 20 years ago, a large number of foreign documents have studied this issue from different aspects and at different levels and proposed corresponding solutions and measures. Nowadays, China has also paid more and more attention to issues such as ammonia pollution, biological environment protection and animal welfare in animal husbandry production. Some countries have even stipulated the content of ammonia gas in housing. In today's vigorous promotion of the "two-oriented society" in our country, how to reduce pollution and save resources are currently the focus of attention. Therefore, this article combines relevant domestic and foreign literature and practical experience, sums up the effective measures for ammonia production and hazards in livestock houses and how to reduce ammonia production and emissions, and provides reference for current livestock production.
1. Ammonia production The source of ammonia in livestock houses is mainly divided into two types: a kind of ammonia in the gastrointestinal tract, which is derived from excrement, gastrointestinal digestive substances, etc. Urinary nitrogen is mainly in the form of urea and is easily urease. Hydrolysis, catalytic generation of ammonia and carbon dioxide. The fecal nitrogen is mainly in the form of organic matter and is not easily decomposed, but it is also a source of nitrogen in the ammonia formation process. The other is environmental ammonia, which is produced by the decomposition of organic matter such as accumulated excrement, feed residue, and bedding. In the case of moist litter, suitable pH and high temperature, a lot of manure and considerable air, ammonia production is faster. The ammonia content in the livestock house depends on the temperature in the house, the stocking density, ventilation, ground structure, feeding and management level, and excrement removal. Since ammonia is highly soluble in water, the concentration of ammonia in high humidity air is relatively high. According to Balins, 50 to 80 kg of pigs discharge 6 kg of excreta per day and 16 to 37 g of nitrogen, of which approximately 60% are urea or amine salts that are easily converted to NH3.
2. Ammonia hazards The water solubility of ammonia is very high. At 20°C, 1L of water dissolves 700L of ammonia. It is a strong irritating gas that can irritate the mucous membranes and can cause various inflammations. The extent to which ammonia affects animals is related to its concentration and animal species. In general, ruminants are more tolerant to ammonia than monogastric animals, and pigs are stronger than chickens.
2.1 Effect on pig growth performance Ammonia can cause rapid growth and metabolism of mucosal cells, which will increase the need for oxygen and energy. At the same time, the detoxification process of ammonia is a highly energy-consuming process. Therefore, animals use energy for growth and production. The corresponding reduction, thus affecting the animal's growth performance. It has been reported that the initial concentration of ammonia on the livestock and poultry is 25 μg/kg, and the concentration of 100 μg/kg of ammonia has a significant effect on the growth performance. Experimental studies conducted by Dai Sifa et al. on a portion of harmful pigs in a closed pig house for pig growth performance showed that 50 μg/kg NH3 levels reduced piglet growth efficiency by 12%; 100 and 150 μg/kg levels reduced growth efficiency by 30%. Cao Jin and other studies have shown that the daily weight gain decreases as the concentration of NH3 in the pig house increases, and the feed-to-weight ratio increases as the concentration of NH3 in the pig house increases, and it can also induce other diseases.
2.2 Reducing body resistance Ammonia in a pig house is inhaled through the respiratory tract, enters the bloodstream via the alveoli, and binds to hemoglobin, which changes hemoglobin to heme, reducing the hemoglobin's ability to carry oxygen, the storage of blood alkali, and the oxidation of hemoglobin. Performance, resulting in anemia and hypoxia, reduce the body's resistance to disease. Wang Mi et al. showed that when the ammonia concentration reached 10-15 μg/kg, the animals' resistance to infection was significantly reduced.
2.3 Induced Diseases Ammonia is a recognized source of stress and one of the most harmful gases in animal housing. Aqueous solution of ammonia is alkaline, it is irritating to mucous membranes, and alkali burning can occur when it is severe. It can cause eye tears, burning, inflammation of the cornea and conjunctiva, and visual disturbances. Ammonia gas entering the respiratory tract can cause cough, bronchitis and bronchitis, pulmonary edema, hemorrhage, dyspnea, suffocation, and even necrosis, causing respiratory disorders. In addition, ammonia dissolves in the mucus of the respiratory mucosa, causing the alkaline pH of the mucus to convert, and the cilia lose their active function, increasing the susceptibility to airborne diseases.
Cao Jin [Study showed that when the ammonia in the pig house reached 15 μg/kg, the experimental pigs began to develop respiratory diseases, atrophic rhinitis occurred at 35 μg/kg, and the incidence of both increased sharply with increasing NH3 concentrations. Foreign research reports. It is proposed that ammonia concentrations above 50 μg/kg can cause respiratory mucosal injury, and outbreaks of pandemic atrophic rhinitis and other epidemic diseases are positively correlated with the concentration of NH3 in piggery. Wenlixin et al. found that in winter, a large number of harmful gas such as ammonia in the pig house accumulates, which will accelerate the occurrence of high fever (highly pathogenic avian influenza), and the mortality of nursery pigs will be even higher.
2.4 Effect of immunization on vaccines Many vaccines that are immunized via nasal drops, eye drops, and sprays are the first to invade respiratory epithelial cells and stimulate the body's immune response. When the ammonia concentration is too high, the effect of this type of cells can be impaired. In addition, high concentrations of ammonia in livestock houses can increase the vaccination response and present respiratory symptoms.
2.5 Hazards to the natural environment Ammonia is a nitrogen-hydrogen compound that reacts with acidic substances in the atmosphere to form ammonium sulfate, ammonium nitrate, and ammonium chloride. In the Netherlands, the deposition of these salts has been identified as a major cause of acidification of the soil, as ammonia releases two Hs and enters the soil as a result of nitrifying bacteria. Excess nitrogen loss will further cause surface water and soil hypertrophy, and supertrophic effects will affect ecosystem diversity. The most sensitive is the aquatic ecosystem. The direct manifestation is the decline of aquatic species. Similarly, sensitive plants, such as conifers, tomatoes, cucumbers, and fruit trees, are destroyed by the excessive application of ammonia-deposited fertilizers.
2.6 Effect of ammonia on human health Ammonia has a great influence on the farmer. For some people, even a concentration of 4 μg/kg causes eye irritation, and 25 μg/kg stimulates soft tissue. Because of the long-term exposure of farmers to ammonia-laden environments, their health will be adversely affected. 25μg/kg is usually the occupational limit concentration of a culture worker working in an ammonia atmosphere for 8 hours per day, while the limiting concentration for short-term exposure is 35μg/kg for 15min, and there is a risk of life at 300μg/kg ammonia concentration, exceeding 2500μg/kg. Kg may be fatal. Breeding workers working in poorly-breathed livestock houses suffer from cough, sputum, asthma, rhinitis, chest tightness, itchy eyes, fatigue, headaches, and fever.
3. Ammonia prevention measures
3.1 Strengthening the Environment Management of Pigsty
3.1.1 Reasonable site selection and scientific design of pig farms should be based on high-desert terrain, open terrain, convenient drainage, good ventilation, surrounded by non-residential areas, chemical plants, slaughterhouses and mining areas and other places with more pollution. The design of pig houses should be reasonable, so that wastes such as manure, litter and sewage can be completely discharged in a timely manner. The ventilation and ventilation are good and the generation of harmful gases in the houses should be minimized.
3.1.2 strengthen daily management, cut off the ammonia source piggery should be promptly and thoroughly clean up wastes such as excreta, sewage, and ensure clean inside. At the same time, the drinking water system should be fully inspected, rinsed and disinfected to ensure smooth water flow, no dripping or leakage, and to keep it dry. Before the arrival of the winter and spring season, heat insulation and heating work should be done well. Warmer stoves can be used for heating. The grass should be replaced frequently to prevent harmful gases from exceeding the standards.
3.1.3 Maintain proper stocking density In the winter and spring, rural farmers need to increase the stocking density in order to save space, maintain the temperature, and increase the number of farmed animals. Due to the high stocking density, the production of ammonia gas increases rapidly with the increase of temperature, which harms animal health. Therefore, in actual production, farmers should take into account the environmental sanitation of the home when they increase the scale of farming.
3.1.4 Establish a Reasonable Ventilation and Ventilation System Reasonable ventilation can remove harmful gases generated in the house in a timely manner. In general, ventilation should be selected at noon, when the weather is fine and the temperature is high.
3.2 Utilize health-raising pig technology, optimize feed formulation, improve nutrition levels, and reduce ammonia emissions. Health care pig raising refers to adopting various technical measures to regulate the sub-health state of the pig body, promote its evolution toward health, and prevent it from reaching the disease. The direction of development. The principle is "to help the evil." The so-called palliative treatment is not as good as a permanent cure. If we want to fundamentally solve the ammonia pollution in pig houses, we must start with the pig itself.
Righting is to maintain or enhance the pig's own disease resistance, also known as active care. The main measures include: First, the use of immune injection method to enhance the specific body resistance of the pig; Second, the application of nutrition and immune regulation methods and other technical means to improve the body's non-specific resistance to disease. Insufficient or unbalanced nutrient supply will affect the specific and non-specific disease resistance of the pig, and nutrition regulation is also an important health measure to improve the disease resistance of the organism.
Evil is to reduce or eliminate all kinds of pathogenic factors, also known as passive care. Common measures to reduce or eliminate various pathogenic factors include: (1) Doing a good job in environmental sanitation. Good hygienic conditions can reduce the pathogenic factors by 60% to 70%, which can greatly reduce the accumulation of ammonia. (2) Disinfection. Avoid the invasion of various harmful diseases and bacteria under ammonia pollution. (3) deworming. The high concentration of ammonia in the pig house is a sufficient condition for the breeding and reproduction of various insects. (4) Add various ammonia-reducing and deodorant substances to the feed. (5) Provide good "feng shui" and feeding management. Wind refers to the appropriate location of the pig house, ventilation to the sun, can reduce the production of ammonia; water refers to the pigs to provide adequate clean drinking water, but also indirectly reduce ammonia emissions. (6) Reasonable feed formulation. details as follows:
3.2.1 Adding synthetic amino acids and reducing the level of crude protein The diet formulated according to the "ideal protein model", ie the amino acid level of the diet is adapted to the amino acid level of the animal, can increase the digestibility, especially the feed protein, amino acid The utilization rate can reduce the generation of ammonia in the house. According to reports, the level of dietary crude protein calculated by the ideal model is lower by 1%, and the release of excrement ammonia gas is reduced by 10% to 12.5%. Using amino acid balanced nutrition technology, appropriate amounts of synthetic amino acids in the basal diet can be added to reduce the level of crude protein, which can not only save protein feed resources, but also reduce nitrogen excretion in livestock and poultry excreta. Experiments showed that under the condition of better amino acid balance in diets, a 2% decrease in dietary protein had no significant effect on animal performance, but nitrogen excretion decreased by 20%. Aarnink et al. simulated the prediction that when the crude protein per kg of diet decreased by 10g, the ammonia nitrogen of the excrement decreased by 9%, and this prediction has been confirmed. Stutton et al. found that the crude protein level of the diet decreased from 18% to 10%, and then the synthetic amino acids were added. The ammonia nitrogen and total nitrogen in the excrement were reduced by 40% and 42%, respectively.
3.2.2 Increased dietary levels of non-starch polysaccharides found that increasing dietary NSP content reduced urinary nitrogen excretion and increased fecal nitrogen excretion. Since the rate of conversion of urine nitrogen to ammonia is significantly higher than that of fecal nitrogen, increasing non-starch polysaccharides in the diet will help reduce ammonia production and emissions. Deng Jianguo et al. performed this study on livestock and poultry and found that complex carbohydrates such as β-glucans and some non-starch polysaccharides can affect the excretion of endogenous nitrogen.
3.2.3 Addition of chemical and biological deodorants to diets At present, additives with good deodorant application include silicates such as zeolites and bentonites. Zeolite adsorbs gas molecules and water molecules through three-dimensional porous channels on the surface, reduces the production of ammonia and other harmful gases in the livestock house, and also reduces the humidity of the air and excrement in the livestock house and achieves the purpose of deodorization. Adding 5% of zeolite to the growing pig diet can increase pig growth performance and reduce ammonia emissions by 21%. In addition to zeolites, silicates such as bentonite and sepiolite are all adsorbable and serve as deodorizers. Shi Qinghe added bentonite in combination with ammonia in manure to reduce the amount of ammonia emitted. At the same time, some researchers added 120mg/kg deodorant to the diet, which significantly reduced the concentration of ammonia in the pigs in the 5th to 7th week of the experiment and increased the pig's daily weight gain by 9.4%.
Plant extracts can eliminate the odor components accumulated in the gastrointestinal tract and achieve the purpose of eliminating odors, and have been widely concerned. The dehumidification and deodorizing premixed feed (ZL2004100232414) developed by Wenlixin associate professor can significantly eliminate the production of harmful gases such as NH3 and H2S. The ginger decontamination agent made from volatile herbs can make the ammonia degradation rate of the livestock house reach 73.9% and the ammonia content in the house is 15.0mL/m-3. In 1978, the American Red Orchid extract was used in pig breeding industry. 65g/T yucca extract was added to the pig feed and 600 piglets and growing pigs were kept for 60 days. The ammonia volatilization of the pighouse was reduced by 26%. Adding yucca extract to pig diets with 16% and 14% crude protein content reduced the ammonia volatilization of the pighouse by 48.8% and 33.50%, respectively.
3.2.4 Adding enzyme preparations or acid preparations to increase nitrogen utilization The addition of enzyme preparations and acid preparations to increase the digestibility of nutrients has been widely confirmed. There are many types of enzyme preparations for feeding, and generally they can be divided into two categories: digestive enzymes and non-digestive enzymes. The substrate and action of digestive enzymes are similar to the digestive enzymes normally secreted by the digestive tract of animals, mainly including amylase, protease, lipase, etc. The non-digestive enzymes mainly include phytase, cellulase, xylanase, Î’-glucanase, pectinase, and the like. In production, these enzyme preparations are selectively used in combination according to the characteristics of the diet.
Zhang Keying et al. showed that the addition of 500 IU/kg phytase to the piglet diet can significantly improve the piglet production performance, increase the ileal digestibility of tryptophan, and improve the utilization of phosphorus and protein. Adding 0.1% of xylanase to the feed of piglets increased the dry matter and nitrogen use efficiency of the feed by 21% and 34%.
Wang Mi et al. added 1% citric acid to piglet rice, and the digestibility of dry matter and crude protein increased by 2.28% and 6.1%. Adding 0.5% lactic acid to the diet of corn-soybean weaned piglets increased the digestibility of dietary nitrogen and dry matter by 36.6% and 9.8%, respectively.
3.2.5 Inhibition of urease and uricase activity By using urease inhibitors and uricase inhibitors, adding probiotics or antibiotics to inhibit the activity of microorganisms that produce enzymes, or by immunizing them with highly immunized egg whites that contain urease-containing antibodies, Reduce ammonia production and improve animal performance.
3.2.6 Intestinal pH Adjustment by Components of the Diet Because ammonia emissions are affected by pH in the excreta, other conditions are the same, the lower the pH, the lower the ammonia emission, and thus the diet can be changed. Components to reduce the pH of pig manure, thereby reducing the ammonia emission. The reduction of dietary protein levels by addition of synthetic amino acids and the addition of NSP to pig diets have been associated with a reduction in the amount of ammonia emitted and a decrease in the pH of the pig excreta. When calcium sulfate, calcium chloride, or calcium benzoate was used instead of 3 or 6 g of calcium carbonate added to calcium carbonate diets, the pH of urine decreased by 1.3 and 2.2, respectively, and the pH of the stored feces also changed similarly. It has been reported that for each 5% increase in sugar beet syrup in pig diets, fecal pH drops by 0.4 to 0.5 and ammonia emissions decrease by approximately 15%. The presence of tea polyphenols in the pig's large intestine increases the number of acidophilic bacteria. 0.07% of catechins are added to pig diets to lower the pH and reduce the concentration of spoilage compounds in the stool.
3.3 Other methods The use of certain chemical substances for the treatment of feces and bedding is very useful for reducing the content of ammonia, which can absorb ammonia in feces and bedding, such as H2O2, potassium permanganate, copper sulfate, benzoic acid, acetic acid, etc. Both have an odor suppressing effect. Using 4% cupric sulfate or 2% benzoic acid to treat the litter can effectively control or reduce the ammonia concentration.
The use of microbial fermentation can also effectively reduce the ammonia concentration in the livestock house. It has been reported that adding 0.25% of Lactobacillus, Bacillus subtilis, and Streptococcus-like mixtures to the feed can achieve optimum performance of the flock, and addition of 0.5% can effectively reduce ammonia in the faeces.
4. Summary and outlook With the rapid development of livestock and poultry husbandry, the harmful gas in livestock and poultry houses—ammonia severely affects the health and productivity of animal organisms—it has become the default fact. Become more and more prominent. How to better control the harmful gas in livestock houses has become the focus of domestic livestock and poultry breeding workers and researchers. For a reasonable ammonia control program, the use of health pig raising technology, from the daily management, feed coordination, metabolism control in vivo and other comprehensive considerations, from the source to control the production of ammonia, to reduce the incidence of disease, so that producers get more Big economic benefits. Plant extract deodorants have the advantages of less addition, rich resources, and stable performance, which will surely become the focus of future research.
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