Introduction: 2021 is the opening year of the "14th Five-Year Plan", standing at the historical intersection of the "two hundred years" goal, the three aspects of "scientific and technological innovation" have pointed out the main direction for us. Promoting academic exchanges on animal nutrition and helping young talents grow is the purpose of the "Yihe Youth Award Activity", and this activity will continue to present their scientific and technological innovation achievements in recent years. Hereby, thank you Shandong Longchang Dongbao for your strong support for this event!
Scientific observation of animal nutrition and feed in central and southern China, Ministry of Agriculture and Rural Affairs
The experimental station recommends young scholars
Researcher Li Fengna is the deputy director and researcher of the Research Center for Healthy Breeding of Livestock and Poultry, Institute of Subtropical Agroecology, Chinese Academy of Sciences
Biography
Research interests: nutrition and meat quality of single-stomach animals
Institute of Subtropical Agroecology, Chinese Academy of Sciences, researcher, doctoral supervisor, deputy director of the Research Center for Healthy Breeding of Livestock and Poultry And Animal Husbandry and Composite Ecology of Agriculture and Animal Husbandry, director of the Animal Nutrition Branch of the Chinese Society of Animal Husbandry and Veterinary Medicine, executive director and deputy secretary-general of the Feed Branch of the China High-tech Industrialization Research Association. He graduated from China Agricultural University with a Ph.D. in agronomy in 2009 and went to the School of Nutritional Sciences at the State University of New Jersey (Rutgers University) for a one-year visiting study in 2015. He has long been committed to the formation mechanism of excellent meat quality of pigs and its nutritional regulation technology, systematically studying the relationship between muscle fiber development and fat deposition and meat quality traits, laying a theoretical foundation for the improvement of pork quality and the efficient utilization of feed resources. In the past 5 years, he has been the first or corresponding author of Science in China: Life Sciences, Animal Nutrition, Journal of Animal Science and Biotechnology, Meat Science, Trends in Pharmacological Sciences, Cytokine & Growth Factor Reviews, Molecular Nutrition and Food Research and other important journals of nutrition at home and abroad have published 45 SCI papers, with a maximum of 153 citations in a single article, 6 national invention patents and software copyrights, 15 national and provincial and ministerial projects, and 2 achievement appraisals in Hunan Province. In 2015, he won the first prize of Chinese Agricultural Science and Technology Achievements of the Ministry of Agriculture, in 2016 he was selected by the Youth Innovation Promotion Association of the Chinese Academy of Sciences, in 2017 he was selected into the "Huxiang Young Talents Support Program" of Hunan Province, in 2019 he was awarded the Outstanding Young Scientist Award of the Guangzhou Branch of the Chinese Academy of Sciences, in 2020 he was funded by the "Jieqing" of Hunan Province, and in the same year he was selected as an outstanding member of the Youth Innovation Promotion Association of the Chinese Academy of Sciences.
Scientific and technological innovation achievements
1. The molecular mechanism of the formation of excellent meat quality traits of the local parmesan pig and its response to the egg-energy ratio of the nutrient level of the feed grain were revealed, and it was found that there was a significant interaction between nutrition, variety and growth stage on nitrogen metabolism and fat deposition in muscle tissue
It was found that the muscle fiber type composition, anabolic capacity and metabolomics characteristics of muscle tissue proteins in different breeds of pigs were different, and there were also significant differences in the expression levels of key enzymes and fatty acid transporters in the dorsal longest muscle metabolism, and the fat content (>5%), saturated fatty acid content and fat anabolic related gene expression level of Bama Xiang pigs were higher than those of long white pigs, but the expression level of PepT1, amino acid transporter, was low; The nutrient level of feed grain can regulate the expression of lipid metabolism-related genes in different types of pig skeletal muscle, and affected by the breed, high egg energy can activate the AKT/mTOR signaling pathway in the longest muscle of parmesan pigs and long white pigs to varying degrees than feeds, thereby significantly improving the synthesis capacity of muscle tissue proteins, and upregulating the expression levels of fat breakdown-related genes such as HSL and LPL in the growth period of long white pigs, reducing fat deposition capacity, and the signaling pathway AKT/mTOR participates in this pathway (British Journal of Nutrition, 2015, tied for first author; Journal of Animal Science and Biotechnology, 2015, Corresponding Author). The above-mentioned research reveals the molecular mechanism of the formation of excellent meat quality traits of local breeds of pigs represented by Bama Xiang pig and the regulatory role of feed-to-egg energy ratio, and elucidates the differences in nitrogen metabolism and fat deposition development of different economic types of pigs and their mechanisms, which is of great reference significance for digging deep into and using the germplasm characteristics of excellent local breeds in China, and the local pig ecological feeding technology formed to help the whole ethnic group in Huanjiang Maonan Autonomous County, Guangxi Province get rid of poverty and become rich (2020).
2. The utilization and deposition mechanism of pig muscle tissue protein and its accompanying energy metabolism under low-protein feeding conditions were elucidated, the fat content in the muscle was increased, and the composition of muscle fiber type was improved
On the basis of the previous discussion on the regulation of the quality traits of different varieties of pork by the ratio of feed to egg, the applicant deeply studied the turnover and utilization mechanism of nitrogen content in muscle tissue under low-protein feeding conditions and its accompanying energy metabolism law, in order to improve the theory of low-protein amino acid balance diet. It was found that pigs were fed low-protein feeds at different growth stages (NRC recommended standards were reduced by 3 percentage points) and supplemented with four restricted amino acids of Lai, egg, threon and tryptophan, and the intramuscular fat content of fattened pigs increased by nearly 40%, the redness value a* increased by about 10%, and the proportion of oxidized muscle fiber types increased, which was conducive to the improvement of pork quality, and the overall improvement of the expression level of amino acid transport receptors SNAT2, LAT1, PAT1 and PAT2 in pig muscle tissue at each growth stage was improved; While protein levels were reduced by 6 percentage points from the NRC recommendation, low-protein diets significantly inhibited pig muscle growth and production performance by adjusting the muscle tissue free amino acid profile, downregulating the mTORC1 protein synthesis pathway, and upregulating the ubiquitinated proteasome protein degradation pathway, increasing the number of positive apoptotic cells in muscle tissue, and reducing the energy state AMP/ATP ratio overall, significantly inhibiting pig muscle growth and production performance Biotechnology, 2016, Corresponding Author; Journal of Agricultural and Food Chemistry，2016; 2017, Corresponding Author). This research provides strong technical support for the application of low-protein feed food in pigs, saves protein feed resources, improves the utilization efficiency of nitrogen nutrients, and improves meat quality traits, and also provides new ideas and references for the implementation of ideal amino acid models and precision nutrition.
3. Elucidating the balanced BCAAs ratio of low-protein feeds improves muscle growth and development and energy distribution by regulating the activity of important signaling pathways such as mTOR/AMPK, reducing body fat rate, and the metabolic intermediate of leucine is more effective in HMB
The utilization efficiency of amino acids is the speed limiting factor that regulates protein synthesis, amino acids are not only the basic units for synthesizing proteins, but also the key metabolites in muscle are considered to be regulatory signals for protein synthesis - nutrient sensors, especially branched-chain amino acids. The applicant confirmed that low-protein feed supplementation with an appropriate proportion of BCAAs can promote the growth and development of porcine muscle tissue by modulating the muscle tissue free amino acid library, upregulating the mTORC1 protein synthesis pathway, and downregulating the ubiquitinated proteasome protein degradation pathway, upregulating the expression of myocyte cytokine IL-15, and reducing the activity of adipose tissue lipoprotein lipase (Journal of Animal Science, 2016, Corresponding Author; Nutrition, 2017, Corresponding Author); Altered energy distribution and lipid metabolism in growing pigs, lipolysis promoted by the Adipokine-AMPKα-mTORC1 signaling pathway, mediated amprk α-SIRT1-PGC-1α signaling pathway to regulate mitochondrial biosynthesis (Journal of Functional Foods, 2018, corresponding author), improved muscle fiber type composition. In further studies, it was found that the metabolic intermediate β-hydroxy-β-methylbutyric acid (HMB) added to low-protein feeds can significantly increase the blood insulin content and muscle tissue protein synthesis rate of piglets, reduce the blood urea nitrogen content and muscle tissue protein degradation rate, thereby improving the utilization of nitrogen nutrients, promoting muscle growth, and its effect is even better than leucine, and the amount of HMB added is less than leucine. Analysis of free amino acid profiles of blood and muscle tissue found that the addition of HMB to low-protein feeds did not cause an imbalance in the proportion of branched-chain amino acids (Journal of Functional Foods, 2019, corresponding author). The above studies show that the balanced branched-chain amino acid ratio of low-protein feeds can exert the important physiological function of leucine as a nutrient receptor signaling molecule, and it is found that HMB can be used as an alternative to leucine in pig low-protein feeds, reducing feed costs while improving the utilization rate of nitrogen nutrients, which has important application value.
4. It was found that myocyte factors and adipocyte cytokines can participate in the "dialogue" between cells as important mediators, adjust the ratio of muscle to adipose tissue, and ultimately improve carcass traits and meat quality
The aforementioned study also shows that branched-chain amino acids, especially leucine, regulate energy distribution between muscle tissue and adipose tissue, but the mechanism of "dialogue" between muscle cells and fat cells is not well understood. From the myocyte factor IL-15 and adipocyte cytokine Chemelin as the entry point, the applicant found that the differentiation stage of co-culture between porcine muscle cells and fat cells, the upregulation of myocyte IL-15 expression and inhibition of the differentiation of fat cells, the downregulation of the regulatory gene c/EBPβ expression in the early differentiation stage, the decrease in the secretion of the fat cytokine Leptin, and the activation of the PI3K/Akt and ERK1/2 signaling pathways. Confirmed the involvement of porcine myocyte factor IL-15 in the interaction of muscle cells and fat cells (Molecular Biology Report, 2014, corresponding author; FASEB Journal, 2015, first author), also found that there are differences in the expression levels of myocyte factors IL-6 and IL-15 in muscle tissue at different physiological stages in piglets (Animal Nutrition, 2015, corresponding author; Journal of Animal Science, 2016, first author), and found that Chemerin inhibits myocyte differentiation by activating the ERK1/2 and mTOR signaling pathways to promote their proliferation, confirming that adipocyte-secreted adipocyte-secreted adipocyte cytokines can act on muscle cells in an autocrine or paracrine manner (Cytokine, 2012, corresponding author); In addition, feed nutrients regulate the expression levels of major adipocytes and muscle cytokines in subcutaneous adipose tissue, dorsal longest muscle, and liver tissue on the back of pigs (Molecular and Cellular Endocrinology, 2013, corresponding author). The results of the study together reveal that myocyte factors and adipocytes are used as effective mediators for regulating the interaction between muscle cells and fat cells, and participate in the regulation of the muscle-adipose tissue ratio of pigs to improve the carcass traits and the overall energy metabolism balance, and also point out the direction for the next step of research work.
Scientific and technological innovation