Baoming Li

Effect of slightly acidic electrolyzed water for inactivating Escherichia coli O157:H7 and Staphylococcus aureus analyzed by transmission electron microscopy.

The use of different available chlorine concentrations (ACCs) of slightly acidic electrolyzed water (SAEW; 0.5 to 30 mg/liter), different treatment times, and different temperatures for inactivating Escherichia coli O157:H7 and Staphylococcus aureus was evaluated. The morphology of both pathogens also was analyzed with transmission electron microscopy. A 3-min treatment with SAEW (pH 6.0 to 6.5) at ACCs of 2 mg/liter for E. coli O157:H7 and 8 mg/liter for S. aureus resulted in 100% inactivation of two cultures (7.92- to 8.75-log reduction) at 25°C. The bactericidal activity of SAEW was independent of the treatment time and temperature at a higher ACC (P > 0.05). E. coli O157:H7 was much more sensitive than S. aureus to SAEW. The morphological damage to E. coli O157:H7 cells by SAEW was significantly greater than that to S. aureus cells. At an ACC as high as 30 mg/liter, E. coli O157:H7 cells were damaged, but S. aureus cells retained their structure and no cell wall damage or shrinkage was observed. SAEW with a near neutral pH may be a promising disinfectant for inactivation of foodborne pathogens.

Impacts of a freedom farrowing pen design on sow behaviours and performance

The limited space in farrowing crate imposes many challenges, such as prolonged farrowing duration and high piglet stillbirth rate. Although the features of farrowing pens compensate for the drawbacks of farrowing crates, they are associated with high piglet crushing mortality caused by the greater space afforded to sows and their rolling-over behaviour. Therefore, a freedom farrowing pen was designed to overcome the drawbacks of both farrowing crates and farrowing pens. The main features of the freedom farrowing pen are its left anti-crushing bar and detachable right anti-crushing bar on the sides of the sow lying area. It also has a 10 cm-high anti-crushing bar in the non-lying area. Eighteen healthy, multiparous Yorkshire sows (3-7 parity) were averaged and randomly assigned to farrowing crates, farrowing pens, and freedom farrowing pens to compare the effects of the farrowing systems on sow behaviour and performance. Results showed that the farrowing duration and the mean piglet birth intervals were longer for the sows in farrowing crates than for those in farrowing pens and freedom farrowing pens (P<0.05), but there was no difference between the sows in farrowing pens and those in freedom farrowing pens (P>0.05). The piglet stillbirth rate was higher for the sows in farrowing crates than for those in farrowing pens and freedom farrowing pens (P<0.001). Crushing mortality was higher among piglets in farrowing pens (P<0.001), but there was no difference between piglets in freedom farrowing pens and those in farrowing crates (P>0.05). The freedom farrowing pen and the farrowing pen allowed sows to turn around and move freely, but because of the different structures of their anti-crushing bars, the increase in sow movement did not cause higher piglet crushing mortality (P>0.05). Sows in freedom farrowing pens were found to be more protective of their piglets.

Model Estimation and Measurement of Ammonia Emission from Naturally Ventilated Dairy Cattle Buildings with Slatted Floor Designs

Abstract Laboratory experiments were carried out in a wind tunnel with a model of a slurry pit to investigate the characteristics of ammonia emission from dairy cattle buildings with slatted floor designs. Ammonia emission at different temperatures and air velocities over the floor surface above the slurry pit was measured with uniform feces spreading and urine sprinkling on the surface daily. The data were used to improve a model for estimation of ammonia emission from dairy cattle buildings. Estimates from the updated emission model were compared with measured data from five naturally ventilated dairy cattle buildings. The overall measured ammonia emission rates were in the range of 11–88 g per cow per day at air temperatures of 2.3–22.4 °C. Ammonia emission rates estimated by the model were in the range of 19–107 g per cow per day for the surveyed buildings. The average ammonia emission estimated by the model was 11% higher than the mean measured value. The results show that predicted emission patterns generally agree with the measured one, but the prediction has less variation. The model performance may be improved if the influence of animal activity and management strategy on ammonia emission could be estimated and more reliable data of air velocities of the buildings could be obtained.

Application of neutral electrolyzed water spray for reducing dust levels in a layer breeding house.

Reducing airborne dust is an essential process for improving hen housing environment. Dust reduction effects of neutral electrolyzed water (pH 8.2) spray were investigated in a commercial tunnel-ventilated layer breeding house during production in northern China. A multipoint sampler was used to measure airborne dust concentration to study the dust reduction effects and distribution in the house. Compared with the control treatment (without spray), airborne dust level was reduced 34% in the 3 hr after spraying 216 mL m−2 neutral electrolyzed water in the breeding house. The dust concentration was significantly higher during the periods of feed distribution (1.13 ± 0.13 mg m−3) and artificial insemination (0.72 ± 0.13 mg m−3) compared with after spray (0.47 ± 0.09 mg m−3) and during lights-off period (0.29 ± 0.08 mg m−3) in the three consecutive testing days (P < 0.05). The experimental cage area was divided into four zones along the length of the house, with zone 1 nearest to the evaporative cooling pad and zone 4 nearest to the fans. The air temperature, relative humidity, airflow rate, and dust concentration were measured at the sampling points of the four zones in 3 consecutive days and mortality of the birds for the duration of a month were investigated. The results showed that the air temperature, airflow rate, dust concentration, and number of dead birds increase from zone 1 to zone 4 in the tunnel-ventilated layer breeding house. Implications: It is difficult to effectively reduce hen house airborne dust levels and limited information is available on airborne dust distribution in tunnel-ventilated hen houses. This work investigates (i) the application of neutral electrolyzed water spray for reducing dust in a layer breeding houses; (ii) dust concentration variations in 24-hr house operation; as well as (iii) the effects of location on dust concentrations. It was demonstrated that neutral electrolyzed water spray can be efficiently used for dust reduction in poultry houses. Further, a better understanding of the dust concentration variations in 24-hr house operation and in different spatial zones can contribute to bird housing environment management and poultry house design so as to improve bird health.

In vitro inactivation of porcine reproductive and respiratory syndrome virus and pseudorabies virus by slightly acidic electrolyzed water

Slightly acidic electrolyzed water (SAEW, pH 5.0-6.5) is a novel disinfectant with environmentally friendly broad spectrum microbial decontamination properties which could have significant utility on farm. Two of the most important pathogenic viruses in pigs are porcine reproductive and respiratory syndrome virus (PRRSV) and pseudorabies virus (PRV). The aim of this study was to evaluate the viricidal effectiveness of SAEW against PRRSV and PRV in vitro under different available chlorine concentrations (ACCs, 30, 50 and 70 mg/L), treatment times (5, 10 and 15 min) and temperatures (4, 20, 40 and 60°C), respectively. SAEW had a strong viricidal activity against both PRRSV and PRV. This activity increased with increasing ACC, treatment time and temperature. PRRSV and PRV titres of 7.0 log(10)TCID(50)/mL and 5.9 log(10)TCID(50)/mL, respectively, were completely inactivated by SAEW at an ACC of ≥ 50 mg/L for 10 min even though SAEW had no negative effect on the host cells. SAEW thus shows promise as a disinfectant for use on pig farms to reduce the spread of both PRRSV and PRV, and to limit the morbidity associated with those viruses.

Application of slightly acidic electrolyzed water for inactivating microbes in a layer breeding house

Lots of microorganisms exist in layer houses can cause bird diseases and worker health concerns. Spraying chemical disinfectants is an effective way to decontaminate pathogenic microorganisms in the air and on surfaces in poultry houses. Slightly acidic electrolyzed water (SAEW, pH 5.0-6.5) is an ideal, environmentally friendly broad-spectrum disinfectant to prevent and control bacterial or viral infection in layer farms. The purpose of this work was to investigate the cleaning effectiveness of SAEW for inactivating the microbes in layer houses. The effect of SAEW was evaluated by solid materials and surface disinfection in a hen house. Results indicate that SAEW with an available chlorine concentration of 250 mg/L, pH value of 6.19, and oxygen reduction potential of 974 mV inactivated 100% of bacteria and fungi in solid materials (dusts, feces, feather, and feed), which is more efficient than common chemical disinfectant such as benzalkonium chloride solution (1:1,000 vol/vol) and povidone-iodine solution (1:1,000 vol/vol). Also, it significantly reduced the microbes on the equipment or facility surfaces (P < 0.05), including floor, wall, feed trough, and water pipe surfaces. Moreover, SAEW effectively decreased the survival rates of Salmonella and Escherichia coli by 21 and 16 percentage points. In addition, spraying the target with tap water before disinfection plays an important role in spray disinfection.

Bactericidal Activity of Slightly Acidic Electrolyzed Water Produced by Different Methods Analyzed with Ultraviolet Spectrophotometric

Abstract Slightly acidic electrolyzed water (SAEW) as a novel antimicrobial agent is generated by electrolysis of dilute hydrochloric acid (HCl) and/or sodium chloride (NaCl) solution in a cell with or without a separating membrane. The ultraviolet absorption spectra were used to determine the concentration of hypochlorous acid (HClO) and hypochlorite ion (ClO–) in SAEW generated by four different methods and their bactericidal efficiency for inactivation of Escherichia coli O157:H7 and Salmonella enteritidis was evaluated. During the production of equivalent available chlorine in SAEW, more HClO was produced by electrolysis of HCl solution in a non-membrane generator and mixing the acid and alkaline electrolyzed water generated in a generator with membrane, compared with the methods of adding HCl to neutral electrolyzed water (NEW) and electrolyzing the mixture of NaCl and HCl solution in a non-membrane cell. At the 10 mg/L available chlorine concentration, SAEW produced by the methods with more HClO generation had significantly higher (p<0.05) bactericidal efficiency for inactivation of both pathogens.

Airborne bacterial reduction by spraying slightly acidic electrolyzed water in a laying-hen house

Spraying slightly acidic electrolyzed water (SAEW) has been considered as a potential approach to reduce airborne bacteria in laying-hen houses. In this study, the effects of spraying SAEW on airborne bacterial reduction were investigated in a laying-hen house as compared with using diluted didecyl dimethyl ammonium bromide (DDAB). Averaged air temperature reduced by approximate 1 °C and average relative humidity increased by 3% at a stable ventilation rate (about 2.5 m3 hr−1 per bird) in the laying-hen house 30 min after spraying (120 mL m−2). Compared with the control without spraying, the airborne bacterial concentration was reduced by about 0.70 and 0.37 log10 colony-forming units (CFU) m−3 in the 4 hr after spraying 120 mL m−2 SAEW (available chlorine concentration [ACC] of 156 mg L−1) and diluted DDAB (active compound concentration of 167 mg L−1), respectively. Compared with spraying diluted DDAB, spraying SAEW was determined to be more effective for reducing airborne bacterial in laying-hen houses. The effects of spraying SAEW and diluted DDAB on airborne bacterial reduction in the laying-hen house increased with the increasing available chlorine concentrations for SAEW (156, 206, 262 mg L−1) and increasing active compound concentrations for diluted DDAB (167, 333, 500 mg L−1), respectively. Spraying SAEW and diluted DDAB with two levels of spraying volumes (120 and 90 mL m−2) both showed significant differences on airborne bacterial reduction in the laying-hen house (P < 0.05). Implications: It is difficult to effectively reduce airborne bacteria in laying-hen houses. This work describes the application of spraying slightly acidic electrolyzed water as a new approach for reducing airborne bacteria in a laying-hen house. The effects of active compound concentrations and spray volumes on the airborne bacterial reductions by spraying SAEW were also investigated. This study provided a new effective and environmentally friendly approach to reduce the airborne bacteria in poultry houses, contributing to bird housing environment management and improving bird health.

Effects of neoprene mat on diarrhea, mortality and foreleg abrasion of pre-weaning piglets

Modern commercial swine farrowing crates are typically equipped with slatted iron floor to improve management efficiency (e.g., ease of manure handling, cleanliness of the farrowing crates and hence improved animal hygiene). However, the bare and hard floor surface can impair the welfare of the sow-litter because of some undesirable impacts on the pigs, such as foreleg abrasion, large temperature gradients between the cold floor surface and the abdomen of the piglets (hence higher susceptibility to diarrhea), and higher pre-weaning mortality or morbidity. Although straw bedding has been shown to be conducive to providing better environment for the sow-litter, use of straw creates challenges in terms of economics, hygiene and manure handling. This study investigates the use of neoprene mat (NM) in key areas of the farrowing crates - underneath the sow and in the piglet suckling area to improve the microenvironment and hence welfare of the sow-litter. Two experiments were conducted, each involving 12 sow-litters. The first experiment was to evaluate the thickness of a rectangular-shaped NM (7, 10 or 13 mm) vs. the slatted iron floor (control or Ctrl) and collect the corresponding animal response data; while the second follow-up experiment was to verify the benefits of supplying an improved, double concave (or H)-shaped NM with 10mm thick (CNM10) vs. Ctrl for the farrowing operation. Results of both experiments demonstrated considerable benefits of the NM placement in the farrowing crates. Specifically, the NM reduced the piglet foreleg lesion area and joint swellings (0% for NM vs. 8-10% for Ctrl during suckling periods in both Expts 1 and 2, P<0.001); reduced pre-weaning piglet crushing mortality (18.5+/-5.0%, 6.7+/-3.3% and 9.1+/-5.2% and for Ctrl, NM7 and NM10 and in Expt 1, P<0.05); and reduced piglet diarrhea morbidity (0.6+/-0.2% for CNM10 vs. 2.7+/-0.3% for Ctrl in Expt 2, P<0.01). Piglets in the NM litters had smaller temperature gradients between the abdomen and the contact floor surface (3.8+/-2.3 degrees C for NM vs. 7.6+/-0.5 degrees C for Ctrl in Expt 1, P<0.001; 9.2+/-0.5 degrees C for CNM10 vs. 15.9+/-0.5 degrees C for Ctrl in Expt 2, P<0.001). Moreover, sows in the NM regimens showed longer transition time when changing from standing to lying position (7.4+/-0.3s for CNM10 vs. 4.5+/-0.2s for Ctrl in Expt 2, P<0.05), indicative of more floor comfort for the NM condition. Results of this study suggest that supply of NM underneath the sow and in the piglet suckling area is conducive to enhancing comfort, health and welfare of the sow and litter.

Reduction of microbial contamination on the surfaces of layer houses using slightly acidic electrolyzed water

The objective of this study was to evaluate the effectiveness of slightly acidic electrolyzed water (SAEW) in reducing pathogens on pure cultures and on cotton fabric surfaces in the presence of organic matter and estimate its efficacy in comparison with povidone iodine solution for reducing pathogenic microorganisms on internal surfaces of layer houses. Pure cultures of E.coli, S.enteritidis, and S.aureus and cotton fabric surfaces inoculated with these strains were treated with SAEW in the presence of bovine serum albumin (BSA). In the absence of BSA, complete inactivation of all strains in pure cultures and on cotton fabric surfaces was observed after 2.5 and 5 min treatment with SAEW at 40 mg/L of available chlorine concentration (ACC), respectively. The bactericidal efficiency of SAEW increased with increasing ACC, but decreased with increasing BSA concentration. Then, the surfaces of the layer houses were sprayed with SAEW at 60, 80, and 100 mg/L of ACC and povidone iodine using the automated disinfection system at a rate of 110 mL/m(2), respectively. Samples from the floor, wall, feed trough, and egg conveyor belt surfaces were collected with sterile cotton swabs before and after spraying disinfection. Compared to tap water, SAEW and povidone iodine significantly reduced microbial populations on each surface of the layer houses. SAEW with 80 or 100 mg/L of ACC showed significantly higher efficacy than povidone iodine for total aerobic bacteria, staphylococci, coliforms, or yeasts and moulds on the floor and feed trough surfaces (P < 0.05). SAEW was more effective than povidone iodine at reducing total aerobic bacteria, coliforms, and yeasts and moulds on the wall surface. Additionally, SAEW had similar bactericidal activity with povidone iodine on the surface of the egg conveyor belt. Results suggest that SAEW exerts a higher or equivalent bactericidal efficiency for the surfaces compared to povidone iodine, and it may be used as an effective alternative for reducing microbial contamination on surfaces in layer houses.