Carbon Dioxide Production in Animal Houses: A literature review

This article deals with carbon dioxide production from farm animals; more specifically, it addresses the possibilities of using the measured carbon dioxide concentration in animal houses as basis for estimation of ventilation flow (as the ventilation flow is a key parameter of aerial emissions from animal houses). The investigations include measurements in respiration chambers and in animal houses, mainly for growing pigs and broilers. Over the last decade a fixed carbon dioxide production of 185 litres per hour per heat production unit, hpu (i.e. 1000 W of the total animal heat production at 20 oC) has often been used. The article shows that the carbon dioxide production per hpu increases with increasing respiration quotient. As the respiration quotient increases with body mass for growing animals, the carbon dioxide production per heat production unit also increases with increased body mass. The carbon dioxide production is e.g. less than 185 litres per hour per hpu for weaners and broilers and higher for growing finishing pigs and cows. The analyses show that the measured carbon dioxide production is higher in full scale animal houses than measured in respiration chambers, due to differences in manure handling. In respiration chambers there is none or very limited carbon dioxide contribution from manure; unlike in animal houses, where a certain carbon dioxide contribution from manure handling may be foreseen. Therefore, it is necessary to make a correction of data from respiration chambers, when used in full scale animal buildings as basis for estimation of ventilation flow. Based on the data reviewed in this study, we recommend adding 10% carbon dioxide production to the laboratory based carbon dioxide production for animal houses with slatted or solid floors, provided that indoor manure cellars are emptied regularly in a four weeks interval. Due to a high and variable carbon dioxide production in deep straw litter houses and houses with indoor storage of manure longer than four weeks, we do not recommend to calculate the ventilation flow based on the carbon dioxide concentration for these houses

Carbon Dioxide Production in Animal Houses: A Literature Review

This article deals with carbon dioxide production from farm animals; more specifically, it addresses the possibilities of using the measured carbon dioxide concentration in animal houses as basis for estimation of ventilation flow (as the ventilation flow is a key parameter of aerial emissions from animal houses). The investigations include measurements in respiration chambers and in animal houses, mainly for growing pigs and broilers.Over the last decade a fixed carbon dioxide production of 185 litres per hour per heat production unit, hpu (i.e. 1000 W of the total animal heat production at 20 oC) has often been used. The article shows that the carbon dioxide production per hpu increases with increasing respiration quotient. As the respiration quotient increases with body mass for growing animals, the carbon dioxide production per heat production unit also increases with increased body mass. The carbon dioxide production is e.g. less than 185 litres per hour per hpu for weaners and broilers and higher for growing finishing pigs and cows.The analyses show that the measured carbon dioxide production is higher in full scale animal houses than measured in respiration chambers, due to differences in manure handling. In respiration chambers there is none or very limited carbon dioxide contribution from manure; unlike in animal houses, where a certain carbon dioxide contribution from manure handling may be foreseen. Therefore, it is necessary to make a correction of data from respiration chambers, when used in full scale animal buildings as basis for estimation of ventilation flow. Based on the data reviewed in this study, we recommend adding 10% carbon dioxide production to the laboratory based carbon dioxide production for animal houses with slatted or solid floors, provided that indoor manure cellars are emptied regularly in a four weeks interval. Due to a high and variable carbon dioxide production in deep straw litter houses and houses with indoor storage of manure longer than four weeks, we do not recommend to calculate the ventilation flow based on the carbon dioxide concentration for these houses

Odor from anaerobic digestion of swine slurry: influence of pH, temperature and organic loading

Farm slurry management from storage and/or treatment is the main source of odors from swine production, which are determined by factors such as operational variations (organic loading), cleaning of facilities and animal diet (pH) or environmental conditions (temperature). The aim of this study was to evaluate the influence of pH, temperature and organic loading on odor generation during anaerobic digestion of swine slurry. The methodology employed batch experimental units under controlled pH (6.0, 6.5, 7.0 and 8.0) and temperature (20, 35 and 55 °C) conditions. Additionally, an Upflow Anaerobic Sludge Blanket (UASB) system was operated under two Organic Loading Rate (OLR) conditions as Chemical Oxygen Demand (COD) (Phase I: 0.4 g L-1 d-1 of COD, Phase II: 1.1 g L-1 d-1 of COD). Odor (batch and UASB reactor) was evaluated by detection and recognition threshold as Dilution Threshold (D-T). Acidic conditions (pH 6.0) and thermophilic temperatures (55 °C) increased odors (1,358 D-T) and acidified the system (Intermediate/Total Alkalinity ratio (IT/TA): 0.85) in batch experiments. Increasing OLR on UASB reactor reduced odors from 6.3 to 9.6 D-T d-1 due to an increase in the production of biogas (0.4 to 0.6 g g-1 COD removed of biogas)

Delegation in Long-Term Relationships

This paper considers the e effcts of a two-period interaction on the decision of a principal to delegate authority to a potentially biased but better informed agent. Compared to the (repeated) one-period case, the agent's first period actions may also signal his type which in turn impacts wages in Period 2. As a result, biased agents have an incentive not to follow their own preferences in Period 1, thereby inducing the principal to delegate more often. Moreover, we find that, depending on the players' relative utilities and the wage schedule, long term relationships will increase aggregate welfare. Finally, to empirically support our findings, we analyse data from the German Socio-Economic Panel (SOEP) which show that temporary workers indeed experience less autonomy in their decisions

Epidemiological trends of HIV/HCV coinfection in Spain, 2015-2019

Altres ajuts: Spanish AIDS Research Network; European Funding for Regional Development (FEDER).Objectives: We assessed the prevalence of anti-hepatitis C virus (HCV) antibodies and active HCV infection (HCV-RNA-positive) in people living with HIV (PLWH) in Spain in 2019 and compared the results with those of four similar studies performed during 2015-2018. Methods: The study was performed in 41 centres. Sample size was estimated for an accuracy of 1%. Patients were selected by random sampling with proportional allocation. Results: The reference population comprised 41 973 PLWH, and the sample size was 1325. HCV serostatus was known in 1316 PLWH (99.3%), of whom 376 (28.6%) were HCV antibody (Ab)-positive (78.7% were prior injection drug users); 29 were HCV-RNA-positive (2.2%). Of the 29 HCV-RNA-positive PLWH, infection was chronic in 24, it was acute/recent in one, and it was of unknown duration in four. Cirrhosis was present in 71 (5.4%) PLWH overall, three (10.3%) HCV-RNA-positive patients and 68 (23.4%) of those who cleared HCV after anti-HCV therapy (p = 0.04). The prevalence of anti-HCV antibodies decreased steadily from 37.7% in 2015 to 28.6% in 2019 (p < 0.001); the prevalence of active HCV infection decreased from 22.1% in 2015 to 2.2% in 2019 (p < 0.001). Uptake of anti-HCV treatment increased from 53.9% in 2015 to 95.0% in 2019 (p < 0.001). Conclusions: In Spain, the prevalence of active HCV infection among PLWH at the end of 2019 was 2.2%, i.e. 90.0% lower than in 2015. Increased exposure to DAAs was probably the main reason for this sharp reduction. Despite the high coverage of treatment with direct-acting antiviral agents, HCV-related cirrhosis remains significant in this population

Glossary of terms on animal housing: interconnecting engineering, physical and physiological definitions

Animal Housing is a multidisciplinary scientific area which requires the involvement of scientists from different fields such as engineers, physicians, animal scientists, veterinarians, etc. Their collaboration requires the establishment and use of a standardized vocabulary that provides consistency and reduces misunderstandings among scientists with diverse background or Nationality. A first dictionary entitled 'Glossary of Terms on Animal Housing: Basic Engineering, Physical and Physiological Definitions' has been prepared by a Working Group (Animal Housing in Hot Climate) established under CIGR-Section II. The glossary made reference to Engineering, Thermal Biology and Environmental physiology disciplines and it aimed at (1) setting-up uniformity in Animal Housing terms related to climatization and to (2) serve as a focal point for the development of valuable new terms and definitions, and become a functional tool for all those involved in this study subject. Furthermore, the glossary can eventually become a background document for opening-up further discussions on the meaning of various terms used in Animal Housing

Desarrollo y evaluación de un sistema informatizado on-line para el registro de medidas de velocidad del aire, temperatura y presión diferencial en granjas avícolas

Experimental research on airflow patterns and thermal comfort in livestock buildings require the development of an on-line multi-point computerized system for environmental measurements. The characteristics, development and tests of such equipment are described in this article. The system was based on a laptop, a data acquisition card with 16 input channels and a set of air temperature, air velocity and differential pressure sensors. Sensors were resistance temperature detectors for temperature and air velocity measurements. The accuracy of the computerized sensing system after calibration was, for air velocity measurements, 0.05 m s–1 in the range of 0.1 to 1.5 m s–1, and from 0.03 to 0.14 m s–1 in the range of 1.5 to 7 m s–1; 0.2°C for air temperature measurements; and 5 Pa for pressure measurements. The system has been used in several research studies in commercial poultry buildings and the developed system has been proven to be robust and stable.El desarrollo de un sistema informatizado on-line y multi-punto para la medida de parámetros ambientales en granjas es necesario para la realización de trabajos de investigación sobre ventilación y confort ambiental. En este artículo se describen las características, desarrollo y utilización de dicho equipo de medida. Éste se compone de un ordenador portátil, una tarjeta de adquisición de datos de 16 canales y un conjunto de sensores de temperatura, velocidad del aire y presión diferencial. Los sensores de temperatura y velocidad del aire son sensores de temperatura resistivos. La precisión del sistema de medida tras la calibración fue de 0,05 m s1 en el rango de 0,1 a 1,5 m s1, y de 0,03 a 0,14 m s1 en el rango de 1,5 a 7 m s1;±0,2°C para medidas de temperatura; y±5 Pa para medidas de presión diferencial. El sistema se ha utilizado en varios trabajos de investigación en granjas avícolas comerciales, comprobándose que es un equipo de medida robusto y estable