This article was published in the Journal of the Chinese Academy of Sciences, No. 6, 2021, entitled "High-quality Development of Ecological Grassland And Animal Husbandry"
HE Zhi-xiong1,2 ZHOU Chuan-she1,2 WANG Min1 YANG Guo3 ZHONG Rong-zhen4 JIAO Jin-zhen1 TANG Shao-xun1 TAN Zhi-liang1,2*
1 Key Laboratory of Subtropical Agroecological Processes, Chinese Academy of Sciences
2 School of Modern Agricultural Sciences, University of Chinese Academy of Sciences
3 Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences
4 Jilin Provincial Key Laboratory of Grassland Animal Husbandry, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences
In order to meet the rigid demand of China's 1.4 billion people for animal products such as meat, eggs and milk, China's animal husbandry industry has made remarkable achievements in quantitative growth in the past 40 years. At present, China raises 1/2 of the world's pigs, 1/3 of the poultry, 1/5 of the sheep and 1/11 of the cattle, and the scale of animal husbandry production ranks the forefront in the world.
On the one hand, China's grass-fed animal husbandry has great potential for development. Statistics show that in 2019, China's annual meat output was 77.59 million tons, of which pork output was 42.55 million tons, beef output was 6.67 million tons, mutton output was 4.87 million tons, poultry meat output was 18.97 million tons; at the same time, poultry egg output was 33.09 million tons and milk output was 32.98 million tons.
Compared with the meat consumption structure of Chinese residents, grain-consuming pigs and poultry accounted for 79%, while herbivorous beef and mutton accounted for only 15%. The distortion of the proportion of grain-consuming pigs and poultry not only reflects the serious irrationality of China's animal husbandry industrial structure, but also does not match China's natural resource endowments and planting by-product resources (with about 400 million hectares of grassland, ranking first in the world, and about 800 million tons of crop straw per year). Compared with developed countries with herbivorous animal husbandry (for example, Herbivorous cattle and mutton in New Zealand and Australia account for 79% and 65% respectively), China's herbivorous animal husbandry has great potential for development.
On the other hand, in the face of the development trend of China's agriculture under the framework of new development stages, new development concepts and new development patterns, it is also an inevitable trend for the development of China's grass-fed animal husbandry to take the road of high-quality transformation and development. Functional agriculture will be the third stage of development after high-yield agriculture and green agriculture, and functional agricultural products are considered to be the development direction of high-end food in the future.
At present, some of China's livestock products have structural relative surplus: the amount of general homogeneous products is large and low, and the supply of high-quality products cannot meet consumer demand. Taking dairy cows as an example, consumers have insufficient confidence in the consumption of domestic dairy products, and with the substantial increase in the import volume of milk powder, the supply and demand of domestic fresh milk are seriously imbalanced.
Therefore, the development of domestic dairy meat functional products in the grass-fed animal husbandry industry is not only the primary task of the high-quality development of herbivorous animal husbandry, but also a new breakthrough in reshaping the national brand and allowing consumers to regain confidence, and it is also the only way to promote China's animal husbandry industry to enter the world's advanced ranks.
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Development status of functional animal products at home and abroad
Functional animal products are a type of functional food based on animal products. In addition to the basic properties of food such as nutrition and sensory function, functional food can also play a positive role in enhancing the body's immune function, preventing diseases, enhancing physical fitness and regulating body function.
The development of functional foods is roughly divided into 3 stages:
The first stage of functional food is mainly a variety of fortified foods, is not the most original functional food that has not been verified by any experiment, and most functional foods in China belong to this category;
The second stage of functional food, which has been proved by human or animal tests to have a physiological regulatory function;
The third stage of functional food is mainly reflected in the thorough study of functional components, that is, on the basis of the second stage of functional food, the structure, content and mechanism of action of functional factors are clarified, and functional factors have a stable form. At present, the research and development of functional foods in developed countries such as Europe and the United States is basically in the third stage.
At this stage, the functional agricultural products developed in China are mainly manifested as foods rich in mineral elements (such as selenium, calcium, zinc, etc.) characterized by the first stage. Functional eggs are a more studied type of animal product. For example, selenium-rich eggs are fed to layer chickens using a feed with higher selenium content such as inorganic selenium or organic selenium, so that selenium is converted into organic selenium in the chicken body and deposited in the egg. The absorption rate of organic selenium in eggs by the human body is as high as 80%, which shows that selenium-rich eggs are better selenium nutritional supplements. In addition, the content of cholesterol, fatty acids, phospholipids, amino acids, minerals, vitamins and carotenoids in eggs is regulated through layer feed, and the production of functional eggs that meet the dietary and nutritional needs of children, the elderly and other groups has also been reported.
Herbivorous livestock beef and lamb are a high-quality source of protein, low in cholesterol, and rich in many essential amino acids and other important minerals. Beef is rich in conjugated linoleic acid, carnitine, sarcosine, biohydrogenated intermediates and other functional components that cannot be compared with pig and poultry meat, which show positive effects on human health in reducing fat intake and preventing diabetes, cancer and cardiovascular disease.
China's herbivorous livestock dairy meat functional products have also been reported in recent years. For example, the National Geographical Indication product "Cypress Seed Lamb", which is known for its tender and fragrant flavor and non-fishy taste, is a high-quality goat meat with high protein, low fat and rich in free amino acids and a variety of trace elements.
In addition, colostrum is considered a functional food with great potential due to its rich bioactive substances such as immunoglobulin, lactoferrin and cytokines that enhance the body's immune function and promote growth and development.
At present, the research and development of functional products of herbivorous livestock milk meat in China is still in its infancy (the first stage of products); with the improvement of the health awareness of the Chinese people and the mining of the functional food market, aiming at the characteristics of the third stage of functional food to carry out fine research and development of functional products of herbivorous livestock milk meat, improving the scientific and technological connotation of the product is of great strategic significance for guiding the production of herbivorous livestock and the scientific diet of residents.
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Cutting-edge scientific and technological issues in the development of dairy meat functional products in the grass-fed animal husbandry industry
Overall objectives of the study of functional products of dairy meat of herbivorous livestock. Through scientific and technological innovation at the three levels of "target analysis - animal production - human health" of herbivorous livestock dairy meat functional products, the formation mechanism of important functional components of dairy meat products is analyzed, the targeted improvement technology of functional components of herbivorous livestock milk meat is constructed, and the relationship between milk meat nutrition and human health is elucidated, which provides basic theoretical support for guiding the design of precise diet and carrying out personalized third-stage development of herbivorous livestock milk meat functional products, and its main research strategy is shown in Figure 1.
Figure 1 Strategic roadmap for research on dairy meat functional products in grass-fed animal husbandry
The function of herbivorous livestock milk products forms a theoretical problem. It mainly focuses on the biological basis and regulation of nutritional processes in herbivorous livestock.
1. From the perspective of its own biological basis, it is necessary to elucidate the genetic basis of important functional components of herbivorous livestock dairy meat products (such as raw meat conjugated linoleic acid, carnitine and sarcosinate, etc.; raw milk lactoferrin and lecithin, etc.), and analyze the key target genes that characterize the important functional components of milk meat and their precursors.
2. From the perspective of nutrient process regulation, it is necessary to elucidate the chemical structure, biosynthesis process and the accumulation law of important functional components in the development process of herbivorous livestock, the threshold range, the influencing factors and their regulatory mechanisms, etc., and how to analyze the digestion, absorption, transport routes and distribution of key nutrients (such as carbohydrates, proteins and lipids) of feed to regulate the quality and function of dairy products. Take fat metabolism as an example: because most unsaturated fatty acids are hydrogenated into saturated fatty acids by microorganisms in the rumen of herbivorous livestock, it is necessary to clarify the relationship between hydrogenation of unsaturated fatty acids in the rumen and the production of yoke linoleic acid in dairy meat products.
Technical problems in animal production based on the enhancement of functional components of dairy meat products. The main problem in the production of herbivorous livestock is how to improve the functional components of dairy meat products through biological and non-biotechnology, based on ensuring their yield and quality.
1. For fresh meat, the quality of meat is usually quantitatively evaluated by indicators such as muscle pH, meat color, system hydraulics, tenderness, intermuscular fat content, thiobarbiturate acid reaction value and flavor score. From the perspective of functional components of fresh meat, the issues that need to be paid attention to in herbivorous livestock breeding include: how to use the technologies of diet amino acid balance, dietary anion balance, diet nitrogen release synchronization index and functional green additives to enhance the content of important functional components such as branched-chain amino acids, phospholipids, conjugated linoleic acid, biohydrogenated intermediates, sarcosine and carnitine in meat products on the basis of environmental friendliness; the appropriate addition forms, additive amount and production costs of functional regulators and animal tolerance doses.
2. For fresh milk, China has formulated strict production and quality standards, and made strict threshold limits for indicators such as milk fat rate, milk protein and non-fat milk solids of fresh milk. On the basis of meeting industry standards, how to improve the content of important functional components of fresh milk (such as lecithin, conjugated linoleic acid, lactoferrin), as well as the dose effect and production cost of fresh milk regulators, is a problem that needs to be paid attention to at the level of dairy herbivorous livestock breeding.
The theoretical basis of the functional components of herbivorous livestock milk meat and human health. It mainly includes: the digestion, absorption and efficacy of important functional components of dairy meat in the human body, and the functional classification of dairy meat products; how the body's immune system, liver, gastrointestinal tract and its microorganisms and other tissues and organs respond after ingesting the functional components of herbivorous livestock milk meat at different ages; how the functional component intake and the physiological process of the human body are compared with the temporal and spatial effects; according to the functional component content of herbivorous livestock milk meat products, the dietary programs of people at different physiological stages and different health levels are formulated.
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Practical exploration of the development of dairy meat functional products in herbivorous animal husbandry
Breeding of new strains using genetic improvement methods
The excellent genetic background of livestock is the basis for the formation of good breeds. Breeding livestock breeds with highly expressed genes of important functional components through breed selection or genetic engineering methods is an effective way to produce functional animal products rich in specific functional components.
For example, lactoferrin is the core nutritional protein that can be extracted from milk, which has a variety of health care functions such as regulating immunity and promoting bone growth for human health. Domestic and foreign researchers use somatic cell cloning technology to obtain human lactoferrin genes, cultivate human lactoferrin clone cows, and improve the content of recombinant human lactoferrin in fresh milk.
High intermuscular fat is the basis for the formation of marbling of beef and mutton, and it is also one of the important factors affecting meat quality. The deposition of intermuscular fat is closely related to the breed, management, nutrition and genetic basis of herbivorous livestock. The ecological grass animal husbandry research team of the Chinese Academy of Sciences has identified the relevant genes affecting the fat deposition between the muscles of sheep in the early stage, screened and constructed the meat trait gene screening chip based on the sheep breed in China, with the goal of producing high-quality lamb, and is carrying out the breeding of new strains of snowflake lamb with high intermuscular fat by using the combined breeding technology of good breeding.
In addition, herbivorous livestock dairy products contain phospholipids that improve cardiovascular health, metabolic diseases and nerve health, especially beef and lamb, which contain higher concentrations of sarcosine and carnitine that increase human muscle and strength. Although these functional ingredients are important functional components that are different from pig and poultry products in herbivorous livestock milk products, there is currently less attention. By analyzing the main control genes of phospholipids, sarcosine and carnitine and other important functional components in herbivorous livestock milk products, and using genetic improvement methods to cultivate phospholipids, sarcosine or carnitine high-expression indigenous herbivorous livestock breeding sources, it is the development direction to realize the functionalization of dairy meat products.
Regulates the diet formula to change the synthesis process of functional ingredients
Because herbivorous livestock have a digestive organ that is very different from that of monogastric animals, the rumen, so that key nutrients show a unique digestive and metabolic mechanism in the animal body.
For example, under the action of rumen microbial fermentation, carbohydrates including crude fibers are degraded to produce short-chain fatty acids as the main energy source of animals, proteins are degraded to ammonia nitrogen and further generate microbial proteins containing various essential amino acids, and unsaturated fatty acids in fats are hydrogenated to generate saturated fatty acids. Researchers at home and abroad have been studying and exploring the regulation of important functional components of dairy products from the perspective of the nutritional metabolism process of herbivorous livestock, of which conjugated linoleic acid is the most studied. Herbivorous livestock milk products are high in conjugated linoleic acid, which has a positive effect on human health in reducing fat intake and preventing diabetes, cancer and cardiovascular disease. Studies have shown that the content of conjugated linoleic acid in dairy meat can be improved by increasing the proportion of herbivorous livestock coarsened and changing the type and quantity of fatty acids.
In the early stage of the study of the application of plant functional ingredients to regulate the quality of grass-fed livestock products, the research team of ecological grass animal husbandry and animal husbandry of the Chinese Academy of Sciences found that adding 3.0-4.0 g/kg catechin to the diet of meat sheep can effectively improve the muscle quality of meat sheep and increase the proportion of unsaturated fatty acids in muscle; the tannins in the diet of lactating sheep are increased, and the content of monounsaturated fatty acids and polyunsaturated fatty acids in sheep milk increases linearly with the increase of tannins added in the diet.
At present, there are few studies on the improvement of important functional components such as phospholipids, sarcosine and carnitine in herbivorous livestock dairy products through dietary regulation methods, and based on their importance in herbivorous livestock dairy products and human nutrition, it is necessary to strengthen the targeted dietary formulation technology and functional feed product research and development for these important functional components.
Targets synthetic herbivorous livestock dairy meat functional component precursors
In recent years, synthetic biology has made remarkable progress in modifying the genetic material and metabolic pathways of microorganisms. The ability to design and synthesize DNA sequences from a simple gene to the genome of the entire microorganism has been developed, and viruses, prokaryote genomes and eukaryote chromosomes have been successfully synthesized.
With the continuous breakthrough of synthetic biology technology, researchers have been able to introduce complex exogenous metabolic pathways in specific microbial hosts and engineer them to achieve directed evolution. For herbivorous livestock, the rumen is inhabited by complex and diverse microorganisms, including bacteria, fungi, archaea and protozoa, which have a variety of species and functional complexity, and can be used as a natural resource library for various functional components (such as amino acids, fatty acids, vitamins).
Based on synthetic biology, the synthetic pathways of precursors of functional components of herbivorous livestock are excavated, and the corresponding synthetic pathways are constructed in rumen mode microorganisms; the metabolic pathways of functional constituent precursors that have been verified by function are combined and synthesized in the form of functional clusters; and the combination optimization of synthetic networks is realized by mining efficient synthetic components, increasing the copy number of key rate-limiting enzymes and introducing molecular regulatory circuits. Targeting the transformation of herbivorous animal rumen specific microorganisms to synthesize functional component precursors, promoting the synthesis and deposition of herbivorous livestock functional meat quality (branched-chain fatty acids and flavored amino acids, etc.) and milk components (conjugated linoleic acid, phospholipids and lactoferrin, etc.), and the application potential in improving the quality of herbivorous livestock milk meat is huge and needs to be tapped.
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Policy recommendations
The development of herbivorous animal husbandry dairy meat functional products is still in the exploratory stage, and it is of great strategic significance to carry out major basic research, major technical research and major product development around the functional products of herbivorous livestock milk meat at the national strategic level, which is of great strategic significance for forming differentiated herbivorous animal husbandry dairy products, creating flagship dairy meat brands, and promoting China's grass-fed animal husbandry to take the road of high-quality development and guiding consumers to healthy diets. For the high-quality development of grass-fed animal husbandry, 2 policy recommendations are proposed.
Improve organizational management
It is necessary to further strengthen the top-level design and coordinate the relevant scientific and technological resources of functional product technology and product research and development in the herbivorous animal husbandry industry. Actively establish close cooperative relations with top academic institutions and scientists at home and abroad, form a scientific research community, exert the initiative and discourse power, seize the commanding heights in several fields, and form a top academic team to establish a number of top academic research platforms.
Strengthen research investment
At the national strategic level, governments at all levels play a guiding role in policy formulation, deploy major scientific and technological tasks around the development of the industrial chain of functional products of grass-fed animal husbandry in response to the consumption needs of different regions and different groups, increase government investment for basic research, and guide enterprises and social capital to invest in the technology research and development and product development of functional products of herbivorous livestock.
background
Since the 20th century, the global population has generally appeared due to overnutrition caused by "rich diseases", such as diabetes, cardiovascular and cerebrovascular diseases, etc., which in turn has led to the concept of functional food. In 2017, the report of the 19th National Congress proposed the development strategy of "Healthy China". Under the background of the great health strategy, the development of functional animal products integrating nutrition and health is not only a powerful hand to drive the supply-side reform of animal husbandry to gradually form a new industrial pattern of high-quality development, but also an important way to help the implementation of the healthy China strategy. From 2020 to 2035, after building a moderately prosperous society in an all-round way and achieving the first centenary goal, China will march towards the second centenary goal. The demand for health products in the whole society is becoming increasingly diversified, differentiated and personalized, and the consumption of animal products such as meat, eggs and milk in the dietary structure of Chinese residents is increasing year by year, and people's requirements for animal product quality will become more and more urgent. In the next 15 years, the size of China's middle-income group is expected to grow from 400 million to 800 million. Strong endogenous market demand will also promote the production and development of high-quality functional animal products to meet the consumer demand of middle-income groups while driving increased product production.
He Zhixiong is a researcher at the Institute of Subtropical Agroecology, Chinese Academy of Sciences. He is mainly engaged in the research of nutrition and physiology of maternal and juvenile herbivores, as well as scientific and technological demonstration work in the areas of beef and mutton fattening, meat quality control, and optimal breeding technology of young animals. In recent years, he has presided over scientific research projects such as the National Natural Science Foundation of China, the Talent Selection Project of the Chinese Academy of Sciences, and the Key Project of the Science and Technology Service Network Program (STS) of the Chinese Academy of Sciences. He has published more than 50 SCI papers in mainstream animal science journals.
Tan Zhiliang, Director and Researcher, Institute of Subtropical Agroecology, Chinese Academy of Sciences. Chief scientist of the innovation team of "Gastrointestinal Health and Breeding Ecological Safety of Livestock and Poultry" in the key areas of the Ministry of Science and Technology, chief scientist of the modern agricultural herbivorous industry technology system of Hunan Province, and vice chairman of the Animal Nutrition Branch of the Chinese Society of Animal Husbandry and Veterinary Medicine. He has won 2 second prizes of the National Science and Technology Progress Award and 4 first prizes of the Hunan Provincial Science and Technology Progress Award. He has presided over more than 30 major scientific and technological projects in Hunan Province, international cooperation projects of the Ministry of Science and Technology, major international (regional) cooperation projects and key projects of the National Natural Science Foundation of China, and published more than 150 SCI papers.
Article from: He Zhixiong, Zhou Chuanshe, Wang Min, Yang Guo, Zhong Rongzhen, Jiao Jinzhen, Tang Shaoxun, Tan Zhiliang. Strategic thinking on the development of dairy meat functional products in herbivorous animal husbandry. Journal of the Chinese Academy of Sciences,2021,36(6):685-691.]