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Abstract Modern ecological breeding has the characteristics of protecting the ecological environment， health， nutrition， delicious， and so on. In the ecological breeding of traditional breeding chicken， using non antibiotic breeding， traditional Chinese medicine and other breeding technologies can not only obtain green， non-harmful and safe food products， but also reduce the cost of farmers and provide breeding efficiency This is a sustainable development path. This paper gave a brief overview of this field.
Key words Ecological breeding mode; Broilers; Laying hens; Research progress
Received： April 23， 2021 Accepted： June 26， 2021
Supported by International Science and Technology Innovation Cooperation Project of Sichuan Province （2020YFH0202）; Key Research and Development Project of Science and Technology Plan of Liangshan Prefecture （20ZDYF0002）.
Huang QIAN （1996-）， female， P. R. China， master， devoted to research about food processing and safety.
*Corresponding author. Lili JI （1982-）， female， P. R. China， associate professor， devoted to research about food science and engineering.
The development of traditional animal husbandry not only provides people with meat food resources， but also brings about problems of animal derived food safety and ecological environment[1]. The development of animal husbandry to modern ecological mode has become an important work in the development of modern characteristic agriculture[2]. Ecological aquaculture is a kind of green， pollution-free scientific and advanced aquaculture technology， which can not only ensure the improvement of the quality and efficiency of aquaculture， but also obtain healthy， green and delicious food products to meet people’s demand for healthy and nutritious food[3-4].
Ecological breeding technology is a kind of breeding method that uses natural environment such as pollution-free water area， mountain， forest， etc. or adopts ecological technology measures to improve the breeding environment， and puts pollution-free feed in the process of breeding or value-added， so as to maximize the restoration of the breeding livestock and poultry growth environment[5]. Ecological breeding has the characteristics of pollution-free， green， high income and low risk[6]. The application of green ecological breeding technology in livestock and poultry breeding can not only meet people’s demand for green products， protect the interests of farmers， but also protect the environment[7]. It has certain economic benefits and ecological value， and can promote the ecological development of modern agriculture[8]. Ecological chickens grow in the natural condition， and hormones and antibiotics are not used. Their meat tastes tender and delicious， and is rich in amino acids， protein and other nutrients[9-10]. Compared with traditional chicken breeding， ecological chickens not only ensure the high quality and safety of the product， but also protect the environment to a certain extent. It is a sustainable breeding method， which has certain use value and practical significance. In this paper， the application of ecological breeding technology in chicken breeding quality selection， breeding mode and non resistance breeding technology in chicken breeding were briefly summarized.
Modern Ecological Breeding Mode
In order to achieve the purpose of ecology， according to different breeding areas， a variety of breeding models have been developed， including outdoor stocking combined with mountain forests， wasteland and fruit forest. They can not only bring into playing to the ecological characteristics of the breeding farm， but also improve the quality of chicken and eggs[11]. Studies have shown that the daily gain， carcass and live weight before slaughter of free-range black bone chickens are higher than those of cage-reared ones， but the feed intake and feed-to-meat ratio of free-range chickens are lower than those of cage-reared ones[12]. Compared with caged chickens， the muscle shear force， muscle water capacity， meat color and crude protein content of free-range chickens were higher than caged chickens， but the crude fat and essential amino acid content of free-range chickens were lower than caged chickens[13]. Free-range chickens have good taste， high nutritional value and are popular with consumers in the market[14]. If the stocking density is too high， the long-term feeding will have a greater ecological impact on the soil and plants， and the free feeding of chickens also has the hidden danger of parasites and other diseases[15]. In Germany and other western countries， due to the limitation of the natural environment， higher requirements for animal welfare， but also to achieve the purpose of ecological breeding， the indoor ground flat breeding mode has been developed. In this model， chickens are reared indoors， the density of breeding is controlled， sufficient light and reasonable feed are given， and modern breeding equipment is used. It can also make the chickens grow healthily without the use of antibiotics and other drugs[16]. Studies have shown that the surface feeding can reduce the incidence rate of chicken leg disease， chest cyst and other diseases， and improve survival rate[17]. The amino acid and linoleic acid content of muscle were significantly increased， and the content of linolenic acid was increased by indoor flat culture[18]. The feed-to-egg ratio， foot pad damage and back feather damage of high density group were significantly higher than those of low and medium density group， but the walking time， rest time and CORT and ACTH in serum of laying hens were lower than those of low and medium density group. The optimal feeding density was 8 hens/m2[19]. Ecological stocking has higher requirements on the natural environment， and indoor flat stocking has higher requirements on the breeding density. The cost of the two ecological breeding modes is high， and the production is also limited. In order to satisfy the consumers’ consumption of ecological chicken and eggs and reduce the breeding cost， the fully closed automatic and semi-automatic breeding mode has entered the field of vision of farmers. The introduction of automation is not only convenient and standardized， but also improves the efficiency of the whole breeding[20]. The key of automatic chicken breeding is mainly from the state of chicken， growth environment， automatic feeding， garbage automatic treatment and other technologies[21]. To realize automation and standardization of chickens raised according to standardized construction， automatic feed supply， automatic drinking water， automatic lighting， automatic fecal and waste cleaning， automatic ventilation and cooling， automatic egg collection and automatic disinfection are required[22-23]. It can provide healthy and safe feed， drinking water and air for chickens， and timely clean up the feces that spread the disease， cut off the possibility of disease transmission. In the whole breeding， it can achieve no antibiotic and no drug use. The quality of eggs and chickens can reach the high-quality ecological level， the breeding cost is greatly reduced， and the product price is more friendly to the people.
Varieties of Modern Ecological Culture
In order to realize the modern ecological breeding， it is very important to select chicken breeds[24]. Chicken breeds are required to have high adaptability and certain commercial value. Sanhuang chicken， Gushi chicken， Langshan chicken， Beijing Red Chicken and other traditional native chicken breeds have strong adaptability to the natural environment and strong disease resistance， so they are suitable for stocking[25-26]. White feathered broiler is the main breed in industrial breeding because of its high meat and egg production ability. However， it is not suitable to be raised in the wild.In the industrial breeding， by combining the four new technology conditions of precision feed coordination;management;disease prevention and environmental control，ecological breeding can also achieve the effect of ecological breeding， and can improve the quality and safety of chicken eggs， improve the economic effect[27]. Yellow feathered broiler is a cross breed of yellow feathered chicken and imported broiler， which has the characteristics of health and delicious. According to the growth and development characteristics of yellow feathered broiler， modern ecological breeding technology carries out ecological healthy breeding from five aspects： brooding device， chicken stage， medium chicken stage， big chicken stage and meat quality conditioning stage， and the products obtained are more nutritious， healthy and safe. It is also one of the modern ecological chicken breeds[28]. It can be seen that the varieties of modern ecological breeding are no longer limited to "native chicken". If the breeding equipment and mode can reach the modern level， "foreign chicken" can also realize ecological breeding， with excellent quality and higher yield. Modern Ecological Breeding and Disease Prevention
Non antibiotic ecological culture
The use of antibiotics in aquaculture will not only produce drug resistance， drug residues in food products， and then reduce the quality of chicken and its products， but also affect human health and cause environmental pollution[29]. Non-antibiotic breeding means that in the process of breeding poultry， no antibiotics， hormones and other exogenous drugs are allowed to be added to the feed. In the process of breeding， the use of antibiotics is strictly controlled within the scope of disease treatment， and the rest period of products is fully followed to ensure that there is no antibiotic residue in poultry products[30]. A large number of researchers have found that in order to achieve non resistant breeding， it is necessary to first select varieties with strong disease resistance， and combine different growth stages with reasonable feed， immune procedures and breeding management methods， improve the immune level of chickens by natural means， strictly control the breeding density， and cut off the route of disease transmission. It can achieve the goal of no resistance culture in the whole culture process， and the meat quality， flavor substances and amino acid content of the products under the culture mode of this technology are better than those of the products with resistance culture[31]. In this breeding mode， most of the traditional native chicken breeds are used， and the breeding time is long. Some researchers have also provided a scheme for non-resistance breeding in chicken breeding combined with clinical biological products， Chinese veterinary drugs and other optional substances[32].
Additive culture of microecological agents
Microecological agents refer to the preparations that can promote the normal growth and reproduction of microbiota and inhibit the growth and reproduction of pathogenic bacteria. Probiotics or their growth promoting substances， which are beneficial and harmless to the host， are made by culture， fermentation， drying and processing based on the principle of microecology[33-34]. Because of the characteristics of non-toxic side effects， no drug resistance， low cost， good effect and no pollution to the environment， probiotics have been recognized by the aquaculture industry[35]. Currently， probiotics are divided into probiotics， prebiotics and synbiotics[36]. Microecological agents can inhibit the growth of harmful microorganisms in animal gastrointestinal tract， ensure the normal flora structure of gastrointestinal tract， improve immunity to a certain extent， so as to promote the growth and development of animals and improve the utilization rate of feed[37]. The study of Miao[38] mentioned that either single or compound lactobacillus preparation can play an important role in the production performance of broilers. The mixture of Lactobacillus acidophilus and Lactobacillus casei plays an important role in improving the feed conversion efficiency in the production performance research of laying hens. The preparation of Streptococcus faecalis can improve the egg weight and protein quality of eggs. Zhang et al.[39] used probiotic fermentation bed culture mode to test Newcastle disease antibody level， avian influenza antibody level and drug resistance of broilers in different 40， 70 and 100 d. The results showed that probiotic fermentation bed culture mode could enhance the resistance of broilers to Newcastle disease and avian influenza virus， but could not significantly improve the drug resistance of Escherichia coli. Probiotics can effectively improve the feed conversion rate， inhibit the growth of E. coli and improve the immune ability of broilers[40]. Microecological preparations have health care effect on Chicken intestines and improve its production performance[41]. Traditional Chinese medicine added culture
Traditional Chinese medicine is a kind of pure natural substance with the good name of "natural antibiotics". It not only contains bactericidal and anti-virus biological components such as flavonoids and saponins， which can directly inhibit or kill pathogenic microorganisms， but also contains substances such as polysaccharides and peptides that can repair and adjust the body and disease resistance ability[42].Yuan Wenjie of Laiyang， Shandong Province， in the breeding of white feathered broilers， according to the different stages of development and growth of the chicken， added different pure Chinese medicine starter to feed. The obtained chicken is not only nutritious and healthy， but also free from disease. Meanwhile， the cost of feeding with Chinese medicine starter is reduced， which is a modern non resistant breeding method worthy of promotion[43]. Traditional Chinese medicine can be used alone or in combination with other drugs， not only the efficacy will not be mutually exclusive， offset， but also complement each other. In the study of Chinese medicine probiotics compound on the growth performance of broilers， four experimental schemes were designed：There is only basic diet in the control group，adding 0.5% compound Chinese medicine， 0.25% probiotics and 0.25% compound Chinese medicine probiotics. The body weight， feed-to-weight ratio and organ index of broilers were taken as indexes to prove that adding appropriate amount of compound Chinese medicine probiotics can improve the growth performance of ecological broilers and promote the development of immune organs[44]. Zhu et al.[45] found that the Chinese medicine probiotics complex can not only increase the weight and reduce the incidence rate， but also increase the income of farmers and increase economic benefits. The results showed that traditional Chinese medicine as an additive in feed production can replace some antibiotics and chemical drugs， which is a new way of safe and pollution-free breeding development[46].
Other epidemic prevention breeding
In addition to the three ways mentioned above， there are also other ways to prevent epidemic breeding. In the application of enzyme preparation in livestock and poultry breeding， it can not only improve the digestibility of feed， regulate animal intestine， kill bacteria and other functions， but also save feed cost and protect the environment[47]. 30% FOS premix （FOS） can improve chicken performance and immune ability， and the optimal FOS supplemental amount is 0.4% in time production[48]. The biological fermented feed contains lower crude fiber and lignin， higher crude protein and crude fat. Meanwhile， the fermented feed contains yeast and its metabolites. After feeding it to chickens， it can promote the chicken intestinal peristalsis， beneficial bacteria breeding， pathogenic bacteria inhibition， improve digestion and absorption ability， in turn， increase the efficiency of feed， and also can improve immune ability， promote animal growth[49]. The application of anti-epidemic breeding technology can not only produce healthy， safe and green products， but also bring considerable economic benefits to farmers. Qian HUANG et al. Modern Ecological Chicken Raising and Its Research Progress
Conclusions
With the improvement of people’s living standards and the enhancement of their awareness of health concepts， people prefer safe， green， healthy and nutritious food. Meanwhile， under the conditions of the new era， we call on us to take good care of the environment and protect our home. The traditional breeding mode needs to be improved， the ecological breeding mode has gradually entered the vision of farmers， and healthy， green， safe and delicious food products have entered people’s lives. For the ecological breeding of chicken， we should start from the selection of chicken breeds， feeding， daily management， feeding environment and other technical aspects. The corresponding chicken and its products are not only nutritious， delicious， green， safe， but also environmentally friendly. In the ecological breeding chicken， the traditional breeding is to select the natural ecological breeding environment， breed the varieties with good disease resistance， and cooperate with microecological agents， traditional Chinese medicine or probiotics to improve the animal resistance. Modern breeding with automation equipment， purification of breeding environment， with scientific and reasonable breeding management methods， provides a non infectious source of growth environment for chickens. Because of the low breeding density， the former is greatly affected by the natural environment， the output is difficult to improve， the cost is high， and the product price is expensive. The latter has high equipment investment， but high breeding density， controllable environment， high output， relatively low cost and low product price. Under the traditional and modern ecological breeding mode， we can produce high-quality chicken and egg products. The application of ecological breeding mode in aquaculture will bring innovation and benefits， meet the needs of people and healthy food， and solve the problems of the relationship between ecology and aquaculture environment， and the conflict between farmers and interests. It is a sustainable development road.
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Key words Ecological breeding mode; Broilers; Laying hens; Research progress
Received： April 23， 2021 Accepted： June 26， 2021
Supported by International Science and Technology Innovation Cooperation Project of Sichuan Province （2020YFH0202）; Key Research and Development Project of Science and Technology Plan of Liangshan Prefecture （20ZDYF0002）.
Huang QIAN （1996-）， female， P. R. China， master， devoted to research about food processing and safety.
*Corresponding author. Lili JI （1982-）， female， P. R. China， associate professor， devoted to research about food science and engineering.
The development of traditional animal husbandry not only provides people with meat food resources， but also brings about problems of animal derived food safety and ecological environment[1]. The development of animal husbandry to modern ecological mode has become an important work in the development of modern characteristic agriculture[2]. Ecological aquaculture is a kind of green， pollution-free scientific and advanced aquaculture technology， which can not only ensure the improvement of the quality and efficiency of aquaculture， but also obtain healthy， green and delicious food products to meet people’s demand for healthy and nutritious food[3-4].
Ecological breeding technology is a kind of breeding method that uses natural environment such as pollution-free water area， mountain， forest， etc. or adopts ecological technology measures to improve the breeding environment， and puts pollution-free feed in the process of breeding or value-added， so as to maximize the restoration of the breeding livestock and poultry growth environment[5]. Ecological breeding has the characteristics of pollution-free， green， high income and low risk[6]. The application of green ecological breeding technology in livestock and poultry breeding can not only meet people’s demand for green products， protect the interests of farmers， but also protect the environment[7]. It has certain economic benefits and ecological value， and can promote the ecological development of modern agriculture[8]. Ecological chickens grow in the natural condition， and hormones and antibiotics are not used. Their meat tastes tender and delicious， and is rich in amino acids， protein and other nutrients[9-10]. Compared with traditional chicken breeding， ecological chickens not only ensure the high quality and safety of the product， but also protect the environment to a certain extent. It is a sustainable breeding method， which has certain use value and practical significance. In this paper， the application of ecological breeding technology in chicken breeding quality selection， breeding mode and non resistance breeding technology in chicken breeding were briefly summarized.
Modern Ecological Breeding Mode
In order to achieve the purpose of ecology， according to different breeding areas， a variety of breeding models have been developed， including outdoor stocking combined with mountain forests， wasteland and fruit forest. They can not only bring into playing to the ecological characteristics of the breeding farm， but also improve the quality of chicken and eggs[11]. Studies have shown that the daily gain， carcass and live weight before slaughter of free-range black bone chickens are higher than those of cage-reared ones， but the feed intake and feed-to-meat ratio of free-range chickens are lower than those of cage-reared ones[12]. Compared with caged chickens， the muscle shear force， muscle water capacity， meat color and crude protein content of free-range chickens were higher than caged chickens， but the crude fat and essential amino acid content of free-range chickens were lower than caged chickens[13]. Free-range chickens have good taste， high nutritional value and are popular with consumers in the market[14]. If the stocking density is too high， the long-term feeding will have a greater ecological impact on the soil and plants， and the free feeding of chickens also has the hidden danger of parasites and other diseases[15]. In Germany and other western countries， due to the limitation of the natural environment， higher requirements for animal welfare， but also to achieve the purpose of ecological breeding， the indoor ground flat breeding mode has been developed. In this model， chickens are reared indoors， the density of breeding is controlled， sufficient light and reasonable feed are given， and modern breeding equipment is used. It can also make the chickens grow healthily without the use of antibiotics and other drugs[16]. Studies have shown that the surface feeding can reduce the incidence rate of chicken leg disease， chest cyst and other diseases， and improve survival rate[17]. The amino acid and linoleic acid content of muscle were significantly increased， and the content of linolenic acid was increased by indoor flat culture[18]. The feed-to-egg ratio， foot pad damage and back feather damage of high density group were significantly higher than those of low and medium density group， but the walking time， rest time and CORT and ACTH in serum of laying hens were lower than those of low and medium density group. The optimal feeding density was 8 hens/m2[19]. Ecological stocking has higher requirements on the natural environment， and indoor flat stocking has higher requirements on the breeding density. The cost of the two ecological breeding modes is high， and the production is also limited. In order to satisfy the consumers’ consumption of ecological chicken and eggs and reduce the breeding cost， the fully closed automatic and semi-automatic breeding mode has entered the field of vision of farmers. The introduction of automation is not only convenient and standardized， but also improves the efficiency of the whole breeding[20]. The key of automatic chicken breeding is mainly from the state of chicken， growth environment， automatic feeding， garbage automatic treatment and other technologies[21]. To realize automation and standardization of chickens raised according to standardized construction， automatic feed supply， automatic drinking water， automatic lighting， automatic fecal and waste cleaning， automatic ventilation and cooling， automatic egg collection and automatic disinfection are required[22-23]. It can provide healthy and safe feed， drinking water and air for chickens， and timely clean up the feces that spread the disease， cut off the possibility of disease transmission. In the whole breeding， it can achieve no antibiotic and no drug use. The quality of eggs and chickens can reach the high-quality ecological level， the breeding cost is greatly reduced， and the product price is more friendly to the people.
Varieties of Modern Ecological Culture
In order to realize the modern ecological breeding， it is very important to select chicken breeds[24]. Chicken breeds are required to have high adaptability and certain commercial value. Sanhuang chicken， Gushi chicken， Langshan chicken， Beijing Red Chicken and other traditional native chicken breeds have strong adaptability to the natural environment and strong disease resistance， so they are suitable for stocking[25-26]. White feathered broiler is the main breed in industrial breeding because of its high meat and egg production ability. However， it is not suitable to be raised in the wild.In the industrial breeding， by combining the four new technology conditions of precision feed coordination;management;disease prevention and environmental control，ecological breeding can also achieve the effect of ecological breeding， and can improve the quality and safety of chicken eggs， improve the economic effect[27]. Yellow feathered broiler is a cross breed of yellow feathered chicken and imported broiler， which has the characteristics of health and delicious. According to the growth and development characteristics of yellow feathered broiler， modern ecological breeding technology carries out ecological healthy breeding from five aspects： brooding device， chicken stage， medium chicken stage， big chicken stage and meat quality conditioning stage， and the products obtained are more nutritious， healthy and safe. It is also one of the modern ecological chicken breeds[28]. It can be seen that the varieties of modern ecological breeding are no longer limited to "native chicken". If the breeding equipment and mode can reach the modern level， "foreign chicken" can also realize ecological breeding， with excellent quality and higher yield. Modern Ecological Breeding and Disease Prevention
Non antibiotic ecological culture
The use of antibiotics in aquaculture will not only produce drug resistance， drug residues in food products， and then reduce the quality of chicken and its products， but also affect human health and cause environmental pollution[29]. Non-antibiotic breeding means that in the process of breeding poultry， no antibiotics， hormones and other exogenous drugs are allowed to be added to the feed. In the process of breeding， the use of antibiotics is strictly controlled within the scope of disease treatment， and the rest period of products is fully followed to ensure that there is no antibiotic residue in poultry products[30]. A large number of researchers have found that in order to achieve non resistant breeding， it is necessary to first select varieties with strong disease resistance， and combine different growth stages with reasonable feed， immune procedures and breeding management methods， improve the immune level of chickens by natural means， strictly control the breeding density， and cut off the route of disease transmission. It can achieve the goal of no resistance culture in the whole culture process， and the meat quality， flavor substances and amino acid content of the products under the culture mode of this technology are better than those of the products with resistance culture[31]. In this breeding mode， most of the traditional native chicken breeds are used， and the breeding time is long. Some researchers have also provided a scheme for non-resistance breeding in chicken breeding combined with clinical biological products， Chinese veterinary drugs and other optional substances[32].
Additive culture of microecological agents
Microecological agents refer to the preparations that can promote the normal growth and reproduction of microbiota and inhibit the growth and reproduction of pathogenic bacteria. Probiotics or their growth promoting substances， which are beneficial and harmless to the host， are made by culture， fermentation， drying and processing based on the principle of microecology[33-34]. Because of the characteristics of non-toxic side effects， no drug resistance， low cost， good effect and no pollution to the environment， probiotics have been recognized by the aquaculture industry[35]. Currently， probiotics are divided into probiotics， prebiotics and synbiotics[36]. Microecological agents can inhibit the growth of harmful microorganisms in animal gastrointestinal tract， ensure the normal flora structure of gastrointestinal tract， improve immunity to a certain extent， so as to promote the growth and development of animals and improve the utilization rate of feed[37]. The study of Miao[38] mentioned that either single or compound lactobacillus preparation can play an important role in the production performance of broilers. The mixture of Lactobacillus acidophilus and Lactobacillus casei plays an important role in improving the feed conversion efficiency in the production performance research of laying hens. The preparation of Streptococcus faecalis can improve the egg weight and protein quality of eggs. Zhang et al.[39] used probiotic fermentation bed culture mode to test Newcastle disease antibody level， avian influenza antibody level and drug resistance of broilers in different 40， 70 and 100 d. The results showed that probiotic fermentation bed culture mode could enhance the resistance of broilers to Newcastle disease and avian influenza virus， but could not significantly improve the drug resistance of Escherichia coli. Probiotics can effectively improve the feed conversion rate， inhibit the growth of E. coli and improve the immune ability of broilers[40]. Microecological preparations have health care effect on Chicken intestines and improve its production performance[41]. Traditional Chinese medicine added culture
Traditional Chinese medicine is a kind of pure natural substance with the good name of "natural antibiotics". It not only contains bactericidal and anti-virus biological components such as flavonoids and saponins， which can directly inhibit or kill pathogenic microorganisms， but also contains substances such as polysaccharides and peptides that can repair and adjust the body and disease resistance ability[42].Yuan Wenjie of Laiyang， Shandong Province， in the breeding of white feathered broilers， according to the different stages of development and growth of the chicken， added different pure Chinese medicine starter to feed. The obtained chicken is not only nutritious and healthy， but also free from disease. Meanwhile， the cost of feeding with Chinese medicine starter is reduced， which is a modern non resistant breeding method worthy of promotion[43]. Traditional Chinese medicine can be used alone or in combination with other drugs， not only the efficacy will not be mutually exclusive， offset， but also complement each other. In the study of Chinese medicine probiotics compound on the growth performance of broilers， four experimental schemes were designed：There is only basic diet in the control group，adding 0.5% compound Chinese medicine， 0.25% probiotics and 0.25% compound Chinese medicine probiotics. The body weight， feed-to-weight ratio and organ index of broilers were taken as indexes to prove that adding appropriate amount of compound Chinese medicine probiotics can improve the growth performance of ecological broilers and promote the development of immune organs[44]. Zhu et al.[45] found that the Chinese medicine probiotics complex can not only increase the weight and reduce the incidence rate， but also increase the income of farmers and increase economic benefits. The results showed that traditional Chinese medicine as an additive in feed production can replace some antibiotics and chemical drugs， which is a new way of safe and pollution-free breeding development[46].
Other epidemic prevention breeding
In addition to the three ways mentioned above， there are also other ways to prevent epidemic breeding. In the application of enzyme preparation in livestock and poultry breeding， it can not only improve the digestibility of feed， regulate animal intestine， kill bacteria and other functions， but also save feed cost and protect the environment[47]. 30% FOS premix （FOS） can improve chicken performance and immune ability， and the optimal FOS supplemental amount is 0.4% in time production[48]. The biological fermented feed contains lower crude fiber and lignin， higher crude protein and crude fat. Meanwhile， the fermented feed contains yeast and its metabolites. After feeding it to chickens， it can promote the chicken intestinal peristalsis， beneficial bacteria breeding， pathogenic bacteria inhibition， improve digestion and absorption ability， in turn， increase the efficiency of feed， and also can improve immune ability， promote animal growth[49]. The application of anti-epidemic breeding technology can not only produce healthy， safe and green products， but also bring considerable economic benefits to farmers. Qian HUANG et al. Modern Ecological Chicken Raising and Its Research Progress
Conclusions
With the improvement of people’s living standards and the enhancement of their awareness of health concepts， people prefer safe， green， healthy and nutritious food. Meanwhile， under the conditions of the new era， we call on us to take good care of the environment and protect our home. The traditional breeding mode needs to be improved， the ecological breeding mode has gradually entered the vision of farmers， and healthy， green， safe and delicious food products have entered people’s lives. For the ecological breeding of chicken， we should start from the selection of chicken breeds， feeding， daily management， feeding environment and other technical aspects. The corresponding chicken and its products are not only nutritious， delicious， green， safe， but also environmentally friendly. In the ecological breeding chicken， the traditional breeding is to select the natural ecological breeding environment， breed the varieties with good disease resistance， and cooperate with microecological agents， traditional Chinese medicine or probiotics to improve the animal resistance. Modern breeding with automation equipment， purification of breeding environment， with scientific and reasonable breeding management methods， provides a non infectious source of growth environment for chickens. Because of the low breeding density， the former is greatly affected by the natural environment， the output is difficult to improve， the cost is high， and the product price is expensive. The latter has high equipment investment， but high breeding density， controllable environment， high output， relatively low cost and low product price. Under the traditional and modern ecological breeding mode， we can produce high-quality chicken and egg products. The application of ecological breeding mode in aquaculture will bring innovation and benefits， meet the needs of people and healthy food， and solve the problems of the relationship between ecology and aquaculture environment， and the conflict between farmers and interests. It is a sustainable development road.
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