Yue Jian

Environmental health and biosecurity in pig farms and surroundings are increasingly threatened by pathogenic bacteria carried by fine particulate matter with an aerodynamic diameter of 2.5 μm or less (PM_2.5) in enclosed piggeries. However, limited attention has been given to these pathogens and their association with the respiratory microbiome of pigs. Using high-throughput sequencing, we investigated the overall and pathogenic bacterial communities attached to PM_2.5 in pig houses, as well as those in the upper (URT) and lower respiratory tracts (LRT) of healthy fattening pigs. Concentrations of PM_2.5, particulate matter with an aerodynamic diameter of 10 μm or less (PM₁₀), ammonia (NH₃), total volatile organic compounds (TVOCs), and hydrogen sulfide (H₂S) were significantly higher inside the piggery than in the surrounding environment. The composition of PM_2.5-associated bacteria varied with sampling height and showed greater similarity to the microbiota of the URT, particularly the oropharynx, than to that of the LRT. Additionally, 140 core potential bacterial pathogens were identified via Venn analysis in both PM_2.5 and respiratory tracts. Co-occurrence network analysis and community assembly patterns revealed that microbial communities in PM_2.5 and the respiratory tract exhibit distinct interaction and assembly characteristics. These findings highlight the potential role of PM_2.5 as a vector for respiratory pathogens and underscore the importance of air quality management in pig farming to safeguard environmental health.

Lighting is an important environmental parameter in livestock farming, which can affect the physiology and behavior of animals, and it can regulate animal production. To explore the comprehensive effects of light intensity and duration on the performance, behavior, and physiological indicators of piglets, a 3 × 2 two-factor experiment (three levels of lighting intensity × two lighting durations) was conducted. The three light intensities used were high (100–120 lux), medium (40–50 lux), and low (5–20 lux). The two lighting durations were 8 h and 10 h of light per day. The experiment used a total of six lighting combinations, which corresponded with the six test units. A total of 96 Landrace–Yorkshire hybrid piglets, with an initial body weight of 13.23 ± 0.18 kg, were randomly assigned to six lit units, four pens per unit, and four piglets per pen. The results showed that lighting intensity and duration had no significant effect on the average daily feed intake, average daily gain, feed/gain, or water consumption of pigs (p > 0.05). For IgM, the main effect caused by the light duration was significant. When the light intensity was 5–20 lux and 40–50 lux, the serum IgM levels of piglets in the 10 h/day light group were 45.80% and 39.54% higher than those in the 8 h/day group, respectively (p < 0.05). For SOD and GSH-Px, the interaction between the lighting duration and intensity was significant (p < 0.05). In the 8 h/day light group, the serum SOD levels of piglets at light intensities of 5–20 lux and 40–50 lux were significantly higher than those at 100–120 lux (p < 0.05). When the light intensity was 5–20 lux and 40–50 lux, the SOD level in the 8 h/day group was significantly higher than that of the 10 h/day group (p < 0.05). The main effect of lighting duration on lying down and abnormal behavior was significant (p < 0.05). In the 8 h/day light group, the abnormal behavior of piglets under a light intensity of 5–20 lux was twice that of 40–50 lux (p < 0.05), and the lying percentage of piglets under a light intensity of 40–50 lux was 14.03% higher than that of piglets under a light intensity of 5–20 lux (p < 0.05). Overall, under the conditions used in this study, although extending the duration of light with an intensity of 40–50 lux to 10 h can improve some immune-related indicators, the extent of this effect was limited. The recommended lighting scheme for piglet houses is a light intensity of 40–50 lux and a lighting duration of 8 h. However, the range of lighting conditions set in this study was still very limited, and various environmental factors must be comprehensively considered in an actual production setting.

Concentrations of critical aerial pollutants within animal farms are important to the health of animals and farm staff and can be reduced via manure management, ventilation control, and barn design. This study characterized measurements of ammonia (NH₃), total suspended particle (TSP), and airborne microbial communities of a large-scale pig-fattening house, as well as their correlations with environmental variables in Southwestern China. Monitoring was conducted for 15 consecutive days during both August and January, at various locations inside the pig house. The concentrations of NH₃ and TSP averaged 3.22 and 0.55 mg m⁻³, respectively, while the average number of airborne microbial colonies was 3.91 log cfu m⁻³. The aerial pollutant concentrations displayed significant seasonal differences (p < 0.05). Specifically, concentrations in winter were significantly higher than those in summer (p < 0.05), and the 07:00 measurements were the highest among the three measurement times. The concentrations were significantly correlated with indoor temperature and relative humidity. In summer, TSP concentration was negatively correlated with temperature (correlation coefficient = −0.732), while NH₃ concentration was positively correlated with temperature (correlation coefficient = 0.58). In winter, TSP and NH₃ concentrations were negatively correlated with relative humidity (correlation coefficients = −0.739 and −0.713, respectively), while the airborne microbial colonies were not correlated with either humidity or temperature in summer or winter. These findings confirm that the aerial pollutant concentrations in a Southwestern China pig-fattening house exhibited significant seasonal and diurnal variations. Air quality can be improved by more precise ventilation control as observed by the correlation of concentrations with ventilation control, indoor temperature, and humidity.