To achieve intelligent feeding, userfriendly humancomputer interaction, and easy maintenance for lactating sows, a set of intelligent and precise feeding systems for lactating sows was designed. This system includes an intelligent feeder, a handheld personal digital assistant terminal, a central controller, and a CANBus bus. It enables convenient onsite management of pig entry and exit management, dynamic monitoring of pig status, and realtime alarm functions for abnormal conditions. In a largescale sow farm in Yunnan Province, 280 intelligent feeders for lactating sows were installed, and a production performance comparison test was carried out with the production line equipped with traditional feeding. The test results showed that intelligent feeding facilitates realized userfriendly humancomputer interaction, touchsensitive feeding, intelligent wet mixing, noncontact operation, and easy maintenance. Compared with traditional feeding, intelligent feeding increased the average daily feed intake of sows by 0.673kg and reduced the daily feed waste by 0.345kg, indicating significant differences (P<0.01) in the average daily feed intake and daily feed waste at different ages between intelligent feeding and traditional feeding. The number of healthy piglets per month increased by 10.44%, the number of healthy piglets per litter increased by 0.69, and the average weight of weaned piglets at 21 days increased by 0.370kg. The backfat loss of lactating sows decreased by 34.43%, and the 7-day weaning estrus rate increased by 4%. The return on investment analysis of the system demonstrated that intelligent feeding effectively reduces feed waste, improves production performance, and has a high return on investment, which can effectively help largescale pig farms reduce costs. This study provides a reference for the development and application of intelligent feeding systems for sows.

In order to solve the problem of environmental pollution caused by the end of intensive farming unorganized air emissions, combined with the principles of pickling and washing spray method, a PLC-based compound air purification platform for livestock and poultry breeding was designed. The platform can view data information and set control parameters through humancomputer interaction interface, automatically complete pickling, washing, waste discharge, adding acid and other work; Ultrasonic atomization dilution of ammonia solution was used to simulate ammonia emissions from livestock and poultry breeding. The distribution of gas concentration in the chamber of the test platform was analyzed with the aid of intelligent environmental monitoring instrument, and the influence of different pH values and organic acids on ammonia purification efficiency was explored. The test results showed that the pH value of the pickling solution had a significant effect on the purification efficiency, the lower the pH value of the solution and the higher the purification efficiency, but when the pH was less than 1.9, the effect was not significant, the purification efficiency was basically constant at about 90%. The average purification efficiency of concentrated sulfuric acid solution (8944%) > the average purification efficiency of acetic acid solution (82.03%) > the average purification efficiency of oxalic acid solution (8104%) > the average purification efficiency of citric acid solution (79.17%) > the average purification efficiency of lactic acid solution (78.73%) > the average purification efficiency of pure water solution (4396%). And with the purification reaction, the pH of concentrated sulfuric acid, oxalic acid and citric acid were more stable, while the pH of acetic acid and lactic acid changed more.

Cold storage energy release is affected by the air flow around it. In this study, an experimental platform based on Particle Image Velocimetry was developed to investigate the influence of factors such as air flow rate, windward surface shape, and placement spacing on the flow field of cold storage plate periphery. Consequently, the air velocity inhomogeneity in outer surface and the gap of cold storage plate increased with the increase in inlet air flow rate. In the test of single cold storage plate, the windward surface shape affected the air velocity of surface of cold storage plate, and the greater the inlet air flow, the more significant the effect. The cold storage plate with rectangular windward plane achieved optimal convection effect under air flow rate Q0 and 3Q0, and the cold storage plate with circular windward plane under air flow rate 5Q0. In the test of double cold storage plate, the average air velocity of the gap rose first and then decreased with increase in inlet air flow, and rose with increase in the placement spacing. The best combination of parameters were obtained when the optimal convection effect was double cold storage plate with circular windward plane, air flow rate was 3Q0 and placement spacing was 4 cm, which achieved average air velocity of surface of 1.82 m/s. The results will provide a reference for optimization of release efficiency of cold storage energy.

The liquid nitrogen filling method has the advantages of high efficiency and low cost, and the liquid nitrogen temperature is low, which can charge and cool the tuna cold storage distribution box. In order to understand the influence of the different cold source introduction parameters on the cold storage characteristics of the tuna cold storage distribution box, a test platform for the tuna cold storage distribution box was set up to study the effects of factors such as liquid nitrogen quality, heat transfer area and cold plate loading on the cold storage characteristics of the cold storage distribution box using quadratic orthogonal rotation combination design. The test results showed that the liquid nitrogen quality, heat transfer area and cold plate loading had significant effects on the cold storage characteristics of the cold storage distribution box. The cooling rate of the air in the box increased with the increase of liquid nitrogen quality and heat transfer area of the cold storage plate, but the cold plate loading had little effect on the cooling rate. With the parameters of 14 kg liquid nitrogen quality and 0.12 m2 heat transfer area, a better cooling rate could be achieved. The cold storage efficiency of the cold storage plate in the box increased with the increase of heat transfer area and cold plate loading and decreased with the increase of liquid nitrogen quality. With the parameters of 6 kg liquid nitrogen quality, 0.12 m2 heat transfer area and 70% cold plate loading, a better cold storage efficiency could be achieved. The research results will provide a reference for the optimization of the cold source introduction of the cold storage distribution box.

In order to understand the change rule of the influencing factors of the environmental regulation of the reserve sow houses in summer, the temperature, relative humidity and ammonia in the reserve sow house were tested by changing the number of fans, fan combination, and wet curtain. The results showed that the more fans were turned on, the greater the range of temperature decrease (the maximum range was 2.66 ℃) and the greater the range of relative humidity increase (the maximum range was 9.76%), the more uniform the distribution of temperature and humidity in the ventilation direction in the reserve sow house. The maximum cooling range was 4.27 ℃, and the maximum increase of relative humidity was 24.17%. When the left and right fans were turned on, the distribution of temperature and humidity in the shed was more uniform than that of the left or right middle fans. The average THI index in the reserve female sheds was 79.5, with a decrease rate of 3.86%, which could effectively alleviate the heat stress of pigs. The uneven coefficient of temperature field and relative humidity field in the reserve piggery were 0.42 and 0.5, respectively, indicating that the distribution of temperature and humidity in the reserve piggery was relatively uniform.