Carbon Footprint Assessment and Mitigation Options of Dairy under Chinese Conditions

With the rapid human population growth and economic development, demand for animal products continues to increase and livestock production rapidly expands. Greenhouse gases (GHG) emission from livestock research 7.52 billion tons CO2-eq per year, accounting for 50% of agricultural emissions and 18% of global anthropogenic GHG emissions (FAO, 2014), making it become an important source of GHG emissions. The Chinese livestock production emits 373 GHG of million tons CO2-eq. Methane (CH4) emitted from enteric fermentation is 10.74 million tons (equivalent to 225.6 million tons CO2-eq), accounting for 60.7% of total livestock GHG emissions. CH4 emitted from manure management is 3.33 million tons (equivalent to 69.9 million tons CO2-eq), accounting for 18.9% of total livestock GHG emissions. Nitrous oxide (N2O) emitted from manure management is 0.25 million tons (equivalent to 77.2 million tons CO2-eq), accounted for 20.4% of the total livestock GHG emissions (MEE, 2018). The enteric fermentation and manure management contribute 40% to agricultural GHG emissions. Expansion of livestock production results in high demand of feedstuffs, bringing greater pressure on natural resources. It is of particular concern that the livestock sector has already been a major user of natural resources. For example, approximately 35% of total cropland and 20% of green water have been used for animal feed production (Opio et al., 2013). Feed-related emissions represent about half of total emissions from livestock supply chains (Gerber et al., 2013). Therefore, it is very important to evaluate GHG emissions from the whole life cycle of livestock production. Besides improved manure utilization and water usage efficiency, management of carbon emissions and carbon footprint is highlighted as an important research topic. This project is expected to identify and execute appropriate interventions for reducing carbon footprint and economic cost of dairy production

Carbon Footprint Assessment and Mitigation Options of Dairy under Chinese Conditions

With the rapid human population growth and economic development, demand for animal products continues to increase and livestock production rapidly expands. Greenhouse gases (GHG) emission from livestock research 7.52 billion tons CO2-eq per year, accounting for 50% of agricultural emissions and 18% of global anthropogenic GHG emissions (FAO, 2014), making it become an important source of GHG emissions. The Chinese livestock production emits 373 GHG of million tons CO2-eq. Methane (CH4) emitted from enteric fermentation is 10.74 million tons (equivalent to 225.6 million tons CO2-eq), accounting for 60.7% of total livestock GHG emissions. CH4 emitted from manure management is 3.33 million tons (equivalent to 69.9 million tons CO2-eq), accounting for 18.9% of total livestock GHG emissions. Nitrous oxide (N2O) emitted from manure management is 0.25 million tons (equivalent to 77.2 million tons CO2-eq), accounted for 20.4% of the total livestock GHG emissions (MEE, 2018). The enteric fermentation and manure management contribute 40% to agricultural GHG emissions. Expansion of livestock production results in high demand of feedstuffs, bringing greater pressure on natural resources. It is of particular concern that the livestock sector has already been a major user of natural resources. For example, approximately 35% of total cropland and 20% of green water have been used for animal feed production (Opio et al., 2013). Feed-related emissions represent about half of total emissions from livestock supply chains (Gerber et al., 2013). Therefore, it is very important to evaluate GHG emissions from the whole life cycle of livestock production. Besides improved manure utilization and water usage efficiency, management of carbon emissions and carbon footprint is highlighted as an important research topic. This project is expected to identify and execute appropriate interventions for reducing carbon footprint and economic cost of dairy production

Performance Evaluation of Manure Nitrogen Output Models Suitable for Lactating Dairy Cows in China

Manure nitrogen (N) output from dairy cattle is a major environmental concern in China. Various empirical models are available to predict manure N output from dairy cattle, but accuracy and precision of these models has not been assessed for Chinese conditions. The objective of this study was to evaluate the performance of extant models that predict different forms of manure N output for lactating dairy cows in China with the aim of identifying the best-fit and most suitable prediction models. A total of 35 empirical models were evaluated for their ability to predict N excretion of dairy cows in China fed a wide range of diets. The data set consisted of 99 treatment means from 32 publications with information on animal and dietary characteristics and N output flows. Performance of models was evaluated using root mean square prediction error (RMSPE) and concordance correlation coefficient (CCC) analysis. The N intake (NI) based model of Kebreab et al. (2010) was selected as best for predicting fecal N excretion (RMSPE = 15.8% and CCC = 0.75). The Reed et al. (2015) model, which also used NI as an input variable, was most suitable for predicting urinary N (RMSPE = 26.0% and CCC = 0.63) and total N (RMSPE = 15.8% and CCC = 0.81). Models predicting urinary urea N (UUN) and urinary N / total N performed poorly. Overall, the deviation of regression line from the equality line (y = x line) for even the best-fit urinary, fecal, and total N excretion models demonstrated the need to develop improved models for use under Chinese conditions. Using N output data from dairy cows in China to develop manure N output models may help improve environmental stewardship of the dairy industry in China

Greenhouse gas emissions on Chinese dairy farms and potential for reduction

A life cycle assessment method was used to calculate the greenhouse gas (GHG) emissions of a sample of 181 dairy farms. A database with survey data of these dairy farms was used to calculate and analyze the resulting GHG emission data. The results show that the annual average carbon footprint of milk from the sample farms is 1.95 kg CO2-eq kg-1 fat and protein corrected milk (FPCM). There are great differences in GHG emission, ranging from 0.82 to 5.09 kg CO2-eq kg-1 FPCM. Regions in south China have the highest carbon footprint, while those in North China have the lowest level. The largest emission source is feed production and processing (31.8%), followed by enteric fermentation (30.0%), manure management (20.8%), energy consumption (9.7%), transport (7.7%) and manure application (7.2%). This large range is caused by different farm conditions and farm management practices, such as herd size, milk yield, and manure management among others. Improving the local dairy production efficiency, manure management, and the integration of crop and dairy production systems are major factors to combine the growing Chinese demand for milk consumption with the global need to reduce GHG emissions. This should be guided through governmental policies, including closing the productivity and efficiency gaps in domestic dairy and feed production, innovations in manure management and the use of green energy. Policy guidelines for the reduction of GHG emissions should take into account differences between regions and farms

A new error bound for linear complementarity problems involving B− B- matrices

In this paper, a new error bound for the linear complementarity problems of $B-$matrices which is a subclass of the $P-$matrices is presented. Theoretical analysis and numerical example illustrate that the new error bound improves some existing results

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

Ammonia and greenhouse gas emissions from co-composting of dead hens with manure as affected by forced aeration rate

The effect of ventilation rate (VR) on ammonia (NH3) and greenhouse gas (GHG) emissions from composting piles of dead hens mixed with hen manure was quantified by measuring the gaseous concentrations and airflow rate through the compost bins. Three VR levels of 0.9, 0.7 and 0.5 m³/hr/bin (equivalent to the air exchanges per hour of 0.9, 0.7 and 0.5) were evaluated, each with three replicates. The compost piles were turned once (on day 58) during the 11-wk composting period. Gaseous concentrations of the inlet and exhaust air of the compost bins were measured using a multi-gas infrared photoacoustic analyzer coupled with a multi-channel sampler; VR was measured with a flow meter; and the emission rate (ER) of each gas was computed from the VR and the gas concentration. Decomposition of the carcass over the 11-wk composting period was found to be greater than 88%, as assessed by the reduction in carcass mass. NH3 ER was relatively stable when the compost pile was at high temperatures (~60?). Sharp increase in carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) emissions occurred quickly after construction of the compost pile. VR was found to significantly affect NH3, CO2 and CH4 emissions (p less than 0.05). Specifically, cumulative emissions per kg of initial co-compost matter for the three VR of 0.9, 0.7 and 0.5 m³/hr/bin were, respectively, 2.4, 2.0 and 1.2 g NH3; 78, 66 and 42 g CO2; 120, 90 and 52 mg CH4; and 6.4, 6.1 and 5.1 mg N2O. Hence, the study results suggest that the rate of forced aeration can be adjusted to reduce NH3 and GHG emissions from animal mortality compositing

Assessment of Tubing Type on Ammonia Gas Adsorption

Different types of tubing and operating conditions may be involved when measuring ammonia (NH3) concentrations and its emissions from animal production facilities. Prices of commercially available tubing vary substantially. A question that has often come up but has not been well investigated is how the tubing type (e.g., PVC vs. FEP) may impact the certainty of NH3 concentration measurement. The study reported here was conducted to address this issue in that it assessed and compared the magnitude of NH3 adsorption to different types of commercially available tubing under conditions that may be present in animal feeding operation (AFO) air emission studies. The types of tubing evaluated were: Teflon® (PFA and FEP tubing), HDPE (clear plastic tubing), and PVC (vinyl tubing). Each tested tubing had a length of 30.5 m (100 ft) and an inside diameter of 6.35 mm (0.25 in.). Five nominal NH3 levels of 10, 20, 40, 80, and 160 ppm, generated with poultry manure, were passed through the tested tubing at an airflow rate of 8 L min-1 (0.28 CFM) for 60 min. Simultaneous measurements of NH3 concentrations at the inlet and outlet of the tested tubing were made with two photoacoustic gas spectrometers (1% repeatability of measured value and 0.2-ppm NH3 detection limit). Although the Teflon tubing had significantly lower NH3 adsorption than the HDPE or PVC tubing, all the tested tubing showed \u3c3% NH3 differences between the inlet and outlet concentrations after the 60-min exposure and mostly \u3c1% for NH3 levels \u3e40 ppm. The results of this study thus suggest that the HDPE and PVC tubing offer viable, more economical air sampling options for AFO NH3 emission studies

Ammonia and Greenhouse Gas Emissions from Co-Composting of Dead Hens with Manure as Affected by Forced Aeration Rate

The effect of ventilation rate (VR) on ammonia and greenhouse gas emissions from co-composting dead hens mixed with hen manure was quantified. Three VR levels of 0.9, 0.7, and 0.5 m3 h-1 were evaluated. Gaseous concentrations were measured using a multi-gas infrared photoacoustic analyzer, VR was measured with flowmeters, and the gas emission rate was computed from the VR and gas concentration. Decomposition of the carcasses over the 11-week composting period was greater than 88%. VR was found to significantly affect NH3, CO2, and CH4 emissions (p \u3c 0.05). Specifically, cumulative emissions per kg of initial matter for VR of 0.9, 0.7, and 0.5 m3 h-1 were, respectively, 2.4, 2.0, and 1.2 g NH3; 78, 66, and 42 g CO2; 120, 90, and 52 mg CH4; and 6.4, 6.1, and 5.1 mg N2O. Hence, the study results suggest that the ventilation rate can be adjusted to reduce NH3 and GHG emissions from animal mortality compositing