Comprehensive evaluation of treating drinking water for laying hens using slightly acidic electrolyzed water.

Slightly acidic electrolyzed water (SAEW) is well-known for its highly potent antibacterial properties and safe residue-free nature. In this study, a comprehensive evaluation was conducted on 2 disinfection methods for waterline cleaning in poultry houses: (1) continuously add SAEW into the waterline and (2) the conventional waterline disinfection method, which includes regular use of high-concentration chemical disinfectant for soaking the waterline and flushing with water. The evaluation focused on the effects of these methods on bacteria levels in laying hens' drinking water, the fecal normal rate of laying hens, egg quality, as well as the economic costs and water footprint associated with each method. The results show that the inhibition rate of the control group was 52.45% to 80.36%, which used 1500 mg/L sodium dichloroisocyanurate (DCCNa) for soaking and then flushing with water. The bacterial levels in the waterline returned to pre-treatment levels 26 h after cleaning. However, the experimental group with an available chlorine concentration (ACC) of 0.3 mg/L SAEW showed a higher inhibition rate (99.90%) than the control group (P < 0.05) and exhibited a sustained antimicrobial effect. Regarding eggshell thickness, eggshell strength, and Haugh units of the egg, there were no significant differences between the experimental and control groups. However, the experimental group had higher egg weight and darker yolk color (P < 0.05) than those of the control group. Besides, the experimental group exhibited a higher fecal normal rate and a lower water footprint than those of the control group. Hence, SAEW represents a favorable choice for disinfecting drinking water in poultry houses due to its ease of preparation, lack of residue, energy efficiency, and efficient antibacterial properties. To ensure adequate sanitation, it is recommended to incorporate SAEW with an ACC of 0.3 mg/L into the daily management of the drinking water system for laying hens.

New insights into concentrations, sources and transformations of NH3, NOx, SO2 and PM at a commercial manure-belt layer house.

Pollutant gases and particulate matters (PM) from livestock facilities can affect the health of animals and farm workers and lead to great social environmental risks. This paper presents a comprehensive study on the characteristics of ammonia (NH3), nitrogen oxides (NOx), sulfur dioxide (SO2) and PM (including PM2.5 and PM10) in a 100,000-bird manure-belt layer house in suburb Beijing for three typical seasons of summer, autumn and winter. Indoor air was sampled at an exhaust fan of the mechanically ventilated commercial house. The monitored indoor concentrations of NH3, NOx, SO2, PM2.5 and PM10 were 3.7-5.0 mg m-3, 17-58 µg m-3, 0-11 µg m-3, 100-149 µg m-3 and 354-828 µg m-3, respectively. The indoor NH3 concentrations were largely influenced by the manure removal frequency. The NOx and SO2 were mainly sourced from the ambient air, and the NOx was also partly sourced from manure decomposition in summer. The indoor PM2.5 and PM10 were largely sourced from the ambient air and the indoor manure, respectively. The abundant indoor NH3 caused significantly higher NH4+ concentration in the indoor PM10 (7.98 ± 9.04 µg m-3) than that in the ambient PM10 (3.48 ± 3.52 µg m-3). Secondary inorganic ions (SO42-, NO3- and NH4+) totally contributed 5.7% and 14.6% to the indoor and ambient PM2.5, respectively; they contributed 2.8% and 8.9% to the indoor and ambient PM10, respectively. Organic carbon was the main component of the PM and accounted for 26.6% and 41.5% of the indoor PM2.5 and PM10, respectively. Heavy metal elements (Zn, Cu and Cr) were likely transported from feed to manure and finally accumulated in the PM. Given the high emission potential, the air pollutants from animal production suggested potential risks for human health.