With the continuous expansion of animal husbandry production scale and the increasing degree of intensification, a large amount of ammonia gas, hydrogen sulfide, skatole, trimethylamine and other malodorous gases and nitrogen and phosphorus in excrement are produced in the livestock production process. Heavy metals, etc., have caused serious environmental pollution; at the same time, with the continuous development of the economy and the gradual improvement of people's quality of life, not only food is required to be rich in nutrition, health and safety, but also requires a good environment for the whole process of production. Therefore, the preparation of ecological nutrient feeds and the reduction of environmental pollution in animal husbandry have become an effective measure to promote the sustainable development of animal husbandry and fundamentally control the pollution of animal husbandry.

1 Proposal of ecological feed

The environmental pollution caused by livestock production mainly comes from the excretion of livestock and poultry excreta and the residues of harmful substances in food. The root cause lies in feed. In order to maximize the production performance of livestock and poultry, livestock and poultry breeders and feed producers tend to increase the concentration of dietary protein in feed preparation, resulting in increased nitrogen excretion in excreta; not paying attention to mineral elements and trace elements in feed. The enrichment of toxic and harmful substances in livestock and poultry and the discharge of imperfect substances, resulting in excessive residues of harmful substances in livestock and poultry, endangering human health, and causing pollution of water and soil after the discharge of phosphorus, copper, arsenic, zinc and pharmaceutical additives. It has worsened people's living environment.

With the further development of animal nutrition research and the increasing awareness of human environmental protection, it has been mentioned on the agenda of solving the public hazard of livestock and poultry products and reducing the environmental pollution of livestock and poultry. Ecological feed is the use of ecological nutrition theory and methods, focusing on the pollution of livestock and poultry products and reducing the environmental pollution of livestock and poultry, from the purchase of raw materials, formula design, processing and feeding, etc., strict quality control, and implementation of animal nutrition regulation In order to control the possible pollution of livestock and poultry products and environmental pollution, so that the feed can achieve low cost, high efficiency and low pollution.

2 Preparation of ecological feed

2.1 Reasonable selection of raw materials

Feed ingredients are the basis of processed feed. The choice of raw materials must first ensure that 90% of the raw materials are derived from the identified green food products and their by-products. Others can be products that meet the green food standards. Secondly, attention should be paid to the purchase of high digestibility and nutrition. Small variation of raw materials. It has been determined that the selection of high digestibility feeds can at least reduce the 5% nitrogen excretion in the excreta. Once again, it is necessary to pay attention to the selection of feeds with low toxic and harmful ingredients and high safety to reduce the environmental pollution caused by the accumulation and discharge of toxic and harmful components in livestock and poultry.

2.2 Precision processing of feed

The precision of feed processing has a great impact on the digestion and absorption of livestock and poultry. Different livestock and poultry have different requirements for feed processing. Li Defa (1994) reported that pig feed pellets ranged from 700 μm to 800 μm, with the highest conversion rate of feed. Using puffing and granulation processing technology, it can destroy and inhibit anti-nutritional factors, toxic and harmful substances and microorganisms in feed, improve feed hygiene, increase nutrient digestibility, and reduce dry matter discharged from manure by one-third.

2.3 Preparing an Amino Acid Balance Diet

Amino acid balanced diet refers to a diet formulated according to the "ideal protein model." A diet in which the amino acid level of the diet is compatible with the amino acid level of the animal. It has been reported that the protein level of the diet can be appropriately reduced on the basis of meeting the needs of effective amino acids. Research data indicates that livestock manure, pens, sewage, waste and harmful gases are related to the composition of livestock and poultry diets. For every 1% reduction in protein content in pig diets, nitrogen emissions were reduced by 8.4%. If the crude protein content in the diet is reduced from 18% to 15%, the nitrogen emissions can be reduced by 25%. If the protein in the chicken diet is reduced by 2%, the amount of nitrogen in the feces can be reduced by 20%. The stench of fecal contamination is mainly caused by protein spoilage and is caused by incomplete absorption of nutrients in the diet. If the dietary protein digestibility is increased or the dietary protein supply is reduced, the production of malodorous substances will be greatly reduced. This not only saves protein resources, but also is an important measure to fundamentally reduce nitrogen pollution in livestock manure.

2.4 Formulating rations based on livestock breeds and their different growth stages

The nutritional needs of different growth stages of animals vary greatly. In the production, the nutritional needs of each stage of the animal and the utilization rate of each nutrient should be accurately estimated. The diet with the same nutritional level and animal physiological needs should be designed. This is the key to reducing nutrient consumption and reducing environmental pollution. Many studies in recent years have shown that formulating diets based on different ages, physiological functions, and environmental changes in livestock and poultry can effectively reduce nitrogen and phosphorus emissions. The amino acid needs to vary with the age and physiological state of the livestock. To minimize the loss of nitrogen, the supply of amino acids must be adjusted frequently. For breeding pigs, the implementation of stage feeding is beneficial for reducing nitrogen excretion. The need for nitrogen in pregnant sows is much lower than that of lactating sows. Reconstituted diet during pregnancy can reduce nitrogen than using the same diet. The discharge amount is 15%-20%, and does not affect the reproductive performance.

3 Rational use of feed additives

Adding enzyme preparations, acidifiers, probiotics, yucca extract, oligosaccharides and Chinese herbal medicine additives to the diet can better maintain the balance of intestinal flora of livestock and poultry, improve feed digestibility and reduce environmental pollution.

3.1 Addition of enzyme preparations Officerh and Batterham (1992) experiments on pigs showed that the apparent digestibility of protein and essential amino acids in pig ileum increased by 9%-12% after the addition of microbial phytase. Studies on broilers have also shown that the addition of phytase to the diet can save 1% of protein and reduce nitrogen excretion by 10% without affecting its performance and carcass quality. At the same time, the addition of microbial phytase can reduce fecal phosphorus excretion by 50%, while the method of reducing exogenous phosphorus addition or increasing feed conversion can only be reduced by 10% (Simous and Versteegh, 1990). Lei et al. (1993) showed that the addition of 750 U/kg phytase to the weaned corn-soybean meal diet showed a linear increase in the utilization of phytase and a 42% reduction in phosphorus excretion in the feces. Adding β-glucanase and xylanase to poultry, piglets or growing or finishing pigs (wheat or barley) basal diets can reduce the stickiness of non-starch polysaccharides and increase the utilization of energy, phosphorus and amino acids .

3.2 Adding acidifiers Acidifiers are mainly used in piglets. Adding 1%-2% citric acid and fumaric acid to weaned piglets can improve feed utilization efficiency by 5%-10%, increase weight gain by 4%-7%, and reduce piglet diarrhea rate by 20%-50%. The effect of adding acid to the piglet diet is related to the type of acidifier, the amount added, and the type of diet. The suitable addition amount of fumaric acid is 2%-3% of the diet, citric acid is 1%, and the lactic acid-based composite acidifier is generally added 0.1%-0.3%. From the type of diet, the effect of acidification of whole plant diets is better than that of large amounts of animal feed. The addition of acidifiers to broiler and yak diets has a certain effect on improving feed utilization, reducing environmental pollution, and promoting animal health and growth.

3.3 Adding probiotics When the activity of harmful bacteria such as Escherichia coli in the intestinal tract of animals is enhanced, it will lead to the conversion of proteins into ammonia, amines and other harmful substances or gases, while probiotics can reduce the excessive production of ammonia and other spoilage substances and reduce intestinal content. The content of ammonia in the matter and feces reduces the content of cresol, sputum, skatole, etc. in the intestinal contents, thereby reducing the odor of the feces. The aminated oxidase and the sulfide-decomposing enzyme produced by Bacillus in the large intestine can completely oxidize the odorant ruthenium compound into a odorless, non-toxic, non-polluting substance. At the same time, Bacillus can also reduce the concentration of blood ammonia in animals. In addition, the addition of Lactobacillus acidophilus, Bifidobacterium, Streptococcus faecalis, etc. in the feed can reduce the ammonia emissions of the animals, purify the air in the house, reduce the nitrogen content in the manure and urine, and reduce the pollution to the environment.

3.4 Adding Yucca Extract In 1982, the American researchers determined the active ingredients in the yucca extract, which can limit the formation of ammonia in the feces and increase the decomposition rate of organic matter, thereby reducing the concentration of ammonia in the air of the livestock house. Stinky effect. The latest research shows that this extract has two active ingredients, one can be combined with ammonia, and the other can be combined with toxic and harmful gases such as hydrogen sulfide and methyl hydrazine, thus having the effect of controlling the malodor of livestock and poultry excrement. At the same time, it can also cooperate with intestinal microbes to break down feed, improve the digestive function of the intestine, promote the absorption of nutrients, and inhibit the activity of urease in the microflora, thereby inhibiting the decomposition of urea and reducing the excretion of livestock and poultry by 40%. -50% ammonia.

3.5 Adding fluorspar, calcification and other fluorite is a natural mineral deodorant. There are many holes inside, which can produce strong electrostatic adsorption. Adding to the feed or spreading it on the ground of the manure and livestock house, or as a carrier for mineral additives, can reduce the temperature and ammonia concentration in the livestock house. At the same time, it can exchange and adsorb some radioactive elements and heavy metal elements, and also has a strong adsorption effect on harmful gases such as ammonia and hydrogen sulfide in the digestive tract of livestock and poultry. If 5% of fluorspar is added to the pig diet, the ammonia content in the excreta can be reduced by 21%. In addition, the addition of calcium sulphate, calcium chloride and calcium benzoate to livestock and poultry diets can also reduce the pH of the feces and thus reduce the volatilization of ammonia.

3.6 Adding oligosaccharides The oligosaccharides currently studied in the animal nutrition community are functional oligosaccharides, which are an animal microecological regulator and an immunopotentiator. In recent years, foreign studies have proved that oligosaccharides have antibiotic-like effects, but they are non-polluting, non-residual, and powerful. Therefore, they have become one of the hot spots for research and development of new ecological nutrient feed additives in animal nutrition. The ideal ecological nutrient feed additive. It can promote the proliferation of beneficial bacteria in the hindgut of animals and improve the health of animals. By promoting the excretion of harmful bacteria and activating animal-specific immunity, the overall immune function of livestock and poultry can be improved, and the occurrence of livestock diseases can be effectively prevented.

3.7 Chinese herbal medicine additives Chinese herbal medicine additives are based on traditional Chinese medicine theory such as natural Chinese herbal medicine (yin and yang, warm and cold), odor (acid, sweet, bitter, spicy, salty) and inter-substance relationship, supplemented by animal feeding and The feed industry is a purely natural green feed additive made from more modern scientific theory and technology. Chinese herbal medicine is a pure natural substance. It has the characteristics of homologous, homologous and common use with food. It is an ideal ecological nutrient feed additive for the feed industry. It can improve the body's metabolism, promote growth and development, improve immune function and prevent and cure. The role of livestock and other diseases. Such as Ai Ye, garlic, Atractylodes, etc., not only can promote the growth and development of livestock and poultry, but also improve the utilization of feed for livestock and poultry.