1. Theory and practice of closed-loop biosafety system


1.1 Biosafety hierarchical management theory.


According to the theory of "Great Wall-Pass Guard", the risk factors of entering the pig farm adopt four types of colors: red, orange, yellow and green: (1) separate levels; (2) draw boundaries; (3) set up gates; (4) block Broken carrier.　　


1.2 Closed-loop biosafety system.


Around each link of the pig industry chain, build the supply end (feed ingredients, feed processing, transportation), production end (supply of materials outside the breeding farm, 3km risk factors, various production units on the farm, etc.), and production back end (contract farms) , Multi-point self-finishing farm), the risk factor management biosafety system at the sales end and the slaughter end. 2. Upstream biosafety of pig supply 　　


2.1 Biosafety of feed mills.
The overall innovation method: one-point production, multi-point distribution, partition management, airtight "supply, production, consumption".


(1) The feed implements the whole process control method, including the selection of raw materials, the transportation process, and the production process to ensure the safety of each link. (2) With reference to the red-orange-yellow-green district management plan, the feed mill adopts various levels of gateway management methods for personnel, materials, and vehicles entering the site. (3) Check the raw material suppliers, discard high-risk raw materials, test each batch of raw materials before purchasing, and select them after they are qualified. (4) The feed pelleting temperature is guaranteed to be 85°C for 3 minutes. (5) All feed transport vehicles use professional transport vehicles, which are cleaned, inspected, and tested according to the process, and used after they are qualified.
2.2 Elimination of 3km risk factors in pig farms


(1) The surrounding environment is mainly aimed at retail farmers within 3km and surrounding key roads. (2) Determine the scope of the clearing group with the help of satellite maps, and conduct a household-by-house inspection of each village in groups. (3) For the main roads around the pig farm, the weekly disinfection frequency shall be established in accordance with the disinfection plan to ensure effective disinfection. (4) Set up a security inspection team to conduct regular inspections around the pig farm every day.　　


2.3 Control of other risk factors


2.3.1 Vehicle control (1) Set up a three-level decontamination system within 5km of the pig farm, which are 5km first-level decontamination, 3km second-level decontamination, and near-farm three-level decontamination. (2) Formulate detailed procedures for the overall vehicle flow, and formulate detailed decontamination procedures for decontamination points at all levels. (3) All personnel in the decontamination center need to undergo professional training and take up their posts after being qualified. (4) In accordance with the biosafety checklist, the biosafety officer conducts an on-site inspection of each vehicle after decontamination.　　 2.3.2 Material management and control (1) Develop detailed material entry procedures.　(2) Set up a material isolation and detoxification point and a food material washing center about 3km away from the pig farm. At the same time, pretreatment functions such as cleaning, cutting, and boiling are performed on the food entering the pig farm. (3) Material isolation and detoxification points and food material washing centers formulate special treatment procedures, and carry out internal pollution-cleaning divisional management. (4) Use a special material transport vehicle to transport materials and food to the gate of the site, and the unloading process follows the management requirements of the clean pollution area. 2.3.3 Personnel management and control (1) Develop detailed personnel entry and exit procedures. (2) Set up personnel isolation points at a distance of about 10km from the field area, where personnel are inspected, changed, bathed, and isolated. (3) After the personnel have undergone detoxification treatment and passed the test, they shall be transported to the site by a special personnel transport vehicle. (4) Entering the venue after going through the dressing, bathing and other detoxification measures again at the entrance of the venue.


3. Biosecurity at the production end


3.1 Group and individual diagnosis


The technicians of the whole field were repeatedly trained, and the head of the house confirmed one-on-one that the person in charge of the building mastered the clinical symptoms of the fourth-stage African swine fever. Report the clinical symptoms of abnormal pigs every day.　


3.2 Three-week purification compass method


The "Three-week Purification Compass Method" is a combination of technology and management methods, including work objectives (to achieve group purification and elimination within 3 weeks), work methods (a new generation of qPCR whole-group detection-precise elimination-comprehensive purification), group Monitoring and other measures.　　 3.2.1 Whole group detection and investigation
(1) Determine the contaminated area, swine nose + anal swab, and the whole group of environmental sampling. (2) Disposal, low pollution state outlier after adequate preparation. (3) Monitor abnormal pigs for 3 weeks. (4) Purification of the pig herd and environment can usually be achieved within 3 weeks, and all monitoring is negative.　3.2.2 Precise removal of positive pigs and threatened pigs
(1) All pigs that test positive every day must be cleared of outliers as soon as possible. (2) Pig driving operation: When positive pigs are driven out of the pig house, all the passages in the house must be covered with carpets and colored strips on both sides, and wetted with disinfectant (Weike 1:100). (3) Pig transfer personnel: the on-site personnel involved in the transfer, the pig-driving personnel, and the off-site personnel wear disposable isolation suits and shoe covers, and immediately undergo harmless treatment after the transfer of pigs.　






3.2.3 Accurate removal of environmental viruses by grid
(1) Divide the pig house into a number of cells according to the arrangement, which are a grid of individual stalls for positive pigs and a grid of overall stalls. (2) The cell grid is fully covered and tested, the positive column is disinfected by flame disinfection + chlorine disinfectant to remove the pathogen, and the negative grid is not processed. (3) Re-examine the grid of positive treatment fields and the threatened grid area, continue to repeat the treatment for positive treatment, and complete environmental pathogen removal for negative treatment. (4) According to the change of grid color, all houses are turned green, that is, all pig herds + environment are cleared and purified.　


4. Rapid laboratory testing system


The new generation of qPCR detection-removal technology is powerfully guaranteed. Based on a comprehensive laboratory detection system, the company has established a nationwide three-level rapid detection and monitoring linkage laboratory system, namely the "three-level detection system", which is 4h sampling and 6h sampling. As a result, there are actions at 12h to provide a strong guarantee.