109 research outputs found
Optimization of Surface Wetting to Cool Broiler Chickens
Surface wetting to cool broiler chickens (46±3 d, 2.8± 0.1 kg) was investigated under 18 acute thermal conditions formed by three dry-bulb temperatures (tdb, 35, 38, and 41 oC) × two dew-point temperatures (tdp,19.4 and 26.1oC) × three air velocity (V, 0.2, 0.7 and 1.2 m ·s-1). The synergistic effects of tdb and tdp were expressed in terms of vapor pressure deficit of the air (VPDair). Surface temperature of the cooled birds was 1.9-2.5 oC lower than that of their control counterparts. Core body temperature (tb) rise of the cooled birds was 1.2, 1.6, and 1.7 oC lower than that of the control birds at 35, 38, and 41 oC, respectively. Increasing V narrowed the difference in tb between the cooled and the control broilers, 2.0, 1.4, and 1.2 oC for V of 0.2, 0.7, and 1.2 m ·s-1, respectively. Increasing tdp from 19.4 to 26.1 oC produced only 0.2 oC overall difference in tb. Results of this study demonstrate that surface wetting coupled with good air movement, as in the case of tunnel ventilation, is effective in relieving heat stress of the birds even under relatively humid conditions. The cooling water needs, expressed as spray interval at a nominal spray dosage of 22 ml ·bird-1 (SI22, min) and evaporation rate (ER, ml/min ·kg0.67), were optimized by relating the SI22 or ER to the thermal conditions, of the form, SI22 = 70.50 – 27.14 . V – 4.84 .VPDair, and ER = - 0.0471 + 0.1700 . V + 0.0297 .VPDair
Acute Synergistic Effects of Air Temperature, Humidity, and Velocity on Homeostasis of Market-Size Broilers
Core body temperature (t b ) of market-size male broilers (46 ± 3 d; 2.8 ± 0.1 kg; Ross × Ross breed) was continuously measured by telemetry during acute, 90- to 240-min exposures to 18 thermally challenging conditions. The thermal conditions consisted of 18 factorial combinations of three dry-bulb air temperatures (t db ; 35°C, 38°C, and 41°C), two dewpoint temperatures (t dp ; 19.4°C and 26.1°C), and three air velocities (V; 0.2, 0.7, and 1.2 m s -1 ). Based on t b rise after 90-min exposures to the thermal conditions, a temperature-humidity-velocity index (THVI) was developed to delineate the synergistic effects of the thermal components on the birds, having the form of THVI = (0.85t db + 0.15t wb ) × V -0.058 , where t wb = wet-bulb temperature. The homeostasis state of the bird was classified as normal, alert, danger, or emergency, which correspond to a t b rise threshold of 1.0°C, 2.5°C, 4.0°C, or \u3e 4.0°C, respectively. These different homeostasis states were functionally and graphically expressed in terms of THVI and exposure time. For example, if the broilers were acutely exposed to a thermal condition for 90 min, then the THVI threshold for the normal, alert, danger, and emergency state would be about 35°C, 38°C, 40°C, and \u3e40°C, respectively. If the exposure duration was increased to 120 min, the THVI threshold would drop to 34°C, 37°C, 38°C, and \u3e38°C, respectively. The results of this study serve as a scientific basis for making management decisions and risk assessment associated with market-size broiler production and handling under thermally challenging conditions
Surface Wetting and its Optimization to Cool Broiler Chickens
Surface wetting to cool broiler chickens (Ross . Ross male, 46 .3 d, 2.8 . 0.1 kg) was investigated under 18 acute thermal conditions formed by 3 . 2 . 3 factorial combinations of dry–bulb temperature (tdb) of 35.C, 38.C, and 41.C; dew–point temperature (tdp) of 19.4.C and 26.1.C; and air velocity (V) of 0.2, 0.7, and 1.2 m s–1. The synergistic effects of tdb and tdp were expressed in terms of vapor pressure deficit of the air (VPDair, kPa). Surface temperature of the cooled birds was 1.9.C to 2.5.C lower than that of their control counterparts. Core body temperature (tb) rise above the normal level for the cooled birds was 1.2.C, 1.6.C, and 1.7.C lower than that for the control birds at 35.C, 38.C, and 41.C, respectively. Increasing V tended to narrow the difference in tb between the cooled and the control broilers, 2.0.C, 1.4.C, and 1.2.C for V of 0.2, 0.7, and 1.2 m s–1, respectively. Increasing tdp from 19.4.C to 26.1.C produced only 0.2.C overall difference in tb. Results of this study demonstrate that surface wetting coupled with good air movement, as in the case of tunnel ventilation, is effective in relieving heat stress of the birds even under relatively humid conditions. The cooling water needs, expressed as spray interval at a nominal spray dosage of 22 mL bird–1 (SI22, min) and evaporation rate (ER, mL/min kg0.67), were optimized by relating the SI22 or ER to the thermal conditions: SI22 = 70.50 – 27.14 V – 4.84VPDair, and ER = –0.0471 + 0.1700 V + 0.0297VPDair
Temperature-Humidity-Velocity Index for Market-size Broilers
A temperature-humidity-velocity index (THVI) for male broilers (46 ± 3 d; 2.8 ± 0.1 kg; Ross × Ross breed) was established based on body temperature (tb) rise of the bird during acute exposure to 18 thermally challenging conditions. The thermal conditions consisted of 18 factorial combinations of 3 dry-bulb air temperature (tdb, 35, 38, and 41 oC), 2 dew-point temperature (tdp, 19.4 and 26.1 oC), and 3 velocity (V, 0.2, 0.7, and 1.2 m/s). The THVI has the form of 058 . 0 ) 15 . 0 85 . 0 ( - × × + × = V t t THVI wb db (where twb = wet-bulb temperature). Homeostasis state of the bird was classified as normal, alert, danger, or emergency that corresponds to a tb rise threshold of 1.0, 2.5, 4.0 or \u3e4.0 oC. These different homeostasis states are functionally and graphically expressed in terms of THVI and exposure time. The results of this study provide a scientific basis for making management decisions and risk assessment associated with marketsize broiler production and handling under adverse thermal conditions
Evaluation of Airborne Dust Concentration And Effectiveness of Cooling fan with Spraying Misting Systems in Swine Gestation Houses
Airborne dust in swine houses can cause serious health problems for humans as well as for animals. The aim of this experiment was to evaluate the airborne dust concentration range and effectiveness of cooling fan with spraying misting systems in the gestation houses in the management practices of China. The experiment was implemented in a gestation barn housed 239 gestation pigs in Hebei Province of China. The tests showed that the average airborne dust concentration was about 4.70 ±3.24 mg/m3 in cold weather and 2.18 ±1.61 mg/m3 in warm weather, respectively. The high dust concentration of 17.55 ± 1.18 mg/ m3 in winter and 15.25 ± 1.77 mg/m3 in summer happened in the feeding period. When the misting cooling system with droplet diameter of 20-50µ m turned on, the average airborne dust concentration could be reduced by 75%, from 7.94 ±4.67 mg/m3 to 1.98 ±1.80 mg/m3, during the feeding period
Daily Variation of Thyroid Hormones in Broiler Under High-Temperature Conditions
Market-size (61-68 day-old) AA broiler chickens were exposed to simulated high-cyclic summer temperatures of North, Central and South China for 5 continuous days. Blood samples were collected at 0AM, 4AM, 8AM, 0PM, 4PM and 8PM each day, and concentrations of triiodothyronine (T3) and thyroxine (T4) were determined by double-antibody radioimmunoassay (RIA). T3, T4 concentration and T3/T4 ratio had two peaks, but the daily variation patterns of thyroid hormones were different between each other. T3 peaked at 12 AM and 12 PM, while T4 peaked at 8 AM and 12 PM, with the two peaks of T3/T4 ratio showing at 4 AM and 12 AM. The lowest concentrations of both T3 and T4 occurred at 4 PM. According to above results, the blood samples should be collected around the time corresponding to the peak of temperature sinusoid, when thyroid hormones (both T3 and T4 concentrations) are used to evaluate the heat stress status of broilers
Temporal Variation of Greenhouse Gas Emission in Gestation Swine Building
The objective of this study was to examine the temporal variation of greenhouse gas (GHG) concentration in the swine building over both daily and seasonal basis. The air samples were collected every one hour continuously for three days during summer and spring, and analyzed by gas chromatography (GC). Barn temperature was collected and the management practices were also noted. Results showed that methane (CH4) and carbon dioxide (CO2) concentration was related to the internal temperature and ventilation. Daily CH4 and CO2 concentrations varied more during cold weather than warmer weather; nighttime GHG concentration in the gestation building was higher than daytime because of the low air exchange. Average CH4 concentration in the gestation building was 16.67 + 9.88 ppm in spring and 9.25 + 7.64 ppm in summer. Average CO2 concentrations were 2361.65 + 960.96 ppm in spring and 1134.96 + 373.53 ppm in summer
Comparative Evaluation of Cooling Systems for Farrowing Sows
The field studies reported here compare the performance of three cooling systems for relieving farrowing/lactating sows of heat stress under the warm and humid production climate in southern China. The comparative systems included (1) tunnel ventilation (TV) with vertical head-zone ventilation (HZV) vs. TV with HZV and drip cooling (DC), (2) TV only vs. TV with DC, and (3) horizontal air mixing (HAM) only vs. HAM and DC. For the HZV, a perforated overhead air duct was used to create an air velocity of 0.6 to 0.8 m/s (118 to 157 ft/min) in the head zone of the sow. The paired tests were conducted successively in an experimental commercial farrowing barn housing 42 sows. Body temperature (Tb) and respiration rate (RR) of the sows were used to evaluate the efficacy of the systems. The results indicate that sows under TV + DC or TV + HZV + DC had significantly lower Tb than those under TV only or TV + HZV (P \u3c 0.01 and P \u3c 0.001, respectively). DC under HAM was less effective for Tb reduction (P \u3e 0.05). DC reduced RR in all cases, 42% under TV (P \u3c 0.01), 41% under TV + HZV (P \u3c 0.01), and 22% under HAM (P \u3e 0.05). It was concluded that TV with DC provides the most cost-effective cooling scheme
Effects of Digestate from Swine Manure Digester on in Vitro Growth of Crop Fungal Pathogens: A Laboratory Study
Anaerobic digestion is one of the most popular methods for swine manure treatment in China, and the resultant digestates are mainly used as fertilizer on arable land. Residues from anaerobic fermentation may be used to mitigate the use of chemical fungicides, but relevant information is lacking. In this lab-scale study, original digestate (OD) from a swine manure-fed digester and centrifuged supernatant liquid (SL) with different storage times (0, 7, 14, or 28 d) were added to potato dextrose agar (PDA) media at a rate of 5% to investigate the effects on in vitro mycelial growth of seven phytopathogenic fungi: Fusarium oxysporum, Sclerotinia sclerotiorum, Rhizotonia cerealis, Bipolaris sorokinianum, Rhizoctonia solani, Exserohilum turcicum, and Bipolaris maydis. Diameters of the fungal colonies were measured at 1 d intervals for 7 consecutive days, and the absolute growth rate (AGR) and growth coefficient (k) were calculated. Results showed that the colony sizes of Fusarium oxysporum, Sclerotinia sclerotiorum, Rhizotonia cerealis, Bipolaris sorokinianum, and Rhizoctonia solani on the OD-treated media were significantly smaller (p \u3c 0.01) than the corresponding controls regardless of the storage time. Similarly, independent of storage time, SL-treated media were shown to significantly (p \u3c 0.01) suppress AGR compared to the controls for all seven fungi except for Exserohilum turcicum, where no significant difference was observed between the 14-day-old SL treatment and control. The average k values of the fungi on the OD-treated media ranged from 29% to 143% of the values on the SL-treated media. The results of this study suggest potential use of digestate for plant disease control, which would reduce the use of chemical fungicides. Further studies are needed to investigate the fungicidal mechanism and fungicidal efficacy of OD and SL under field conditions
Ammonia, Methane, and Carbon Dioxide Concentrations and Emissions of a Hoop Grower-Finisher Swine Barn
Hoop structures have been used quite widely for animal production in the U.S. due to their lower capital costs and multi-purpose versatility. Hoop barns for grower-finisher (G-F) swine production have attracted attention in China as an alternative, environmentally friendly, and water-saving production system. This study was conducted to assess concentrations and emissions of ammonia (NH3) and greenhouse gases (GHGs) for a hoop G-F pig barn at a commercial pig operation in suburban Beijing, China. The NH3 and GHG concentrations and emissions of the facility were measured for three consecutive days during spring and summer seasons. The results revealed the following hourly gaseous concentrations (mean ±SD, mg m-3): 5.9 ±2.7 NH3, 2,183 ±1,376 CO2, and 4.0 ±2.5 CH4 in spring, and 6.8 ±3.4 NH3, 1,530 ±364 CO2, and 5.0 ±2.3 CH4 in summer. The estimated gaseous emissions averaged, in g pig-1 d-1, 22.7 NH3, 2,003 CO2, and 6.7 CH4, or in g AU-1 d-1 (AU = 500 kg), 124 NH3, 11,264 CO2, and 36.2 CH4. The emission values from this study, while being generally comparable with those reported in the literature, add new information concerning emissions from alternative swine housing system
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