GLOBAL WARMING FROM POULTRY FARMING-IT’S STRATEGIES & MITIGATING MEASURES FROM INDIA’S PROSPECTIVE
Compiled & Edited by-DR RAJESH KUMAR SINGH ,JAMSHEDPUR, 9431309542,rajeshsinghvet@gmail.com
The on-going debate on global warming in Davos, Switzerland in the World Economic Forum where the issues related to the global warming has left some people convinced that human activity is seriously impacting climate change. Others are skeptical and dismissive. Whether you believe global warming is real or imagined, we know that the atmospheric concentrations of certain gases are increasing rapidly to levels that we have not seen before .While the impacts of these increased concentrations on climate is less certain, it is believed that these gases will trap heat in the atmosphere and could lead to global warming. Therefore, agriculture and other sectors poultry farming in the developing world in particular are under increasing public pressure to reduce emissions of these gases. Even still, by knowing the carbon footprint (energy use) of your operation, you can not only reduce your energy usage, but also improve your bottom line. While the figures for contribution to greenhouse gas emission by poultry production appear to be low, understanding how these GHG are generated and what we in the poultry industry can do to further reduce our impact remains important.
Livestock are responsible for 18 per cent of the greenhouse gases that cause global warming, more than cars, planes and all other forms of transport put together.
What are Greenhouse Gases?
Human activities, including modern agriculture, contribute to GHG emissions. Greenhouse gasses are defined by their radiative forces – defined as the change in net irradiance at atmospheric boundaries between different layers of the atmosphere – which change the Earth’s atmospheric energy balance. These gases can prevent heat from radiating or reflecting away from the Earth and thus may result in atmospheric warming. A 1996 report published by the International Panel on Climate Change showed that GHG levels have increased since the Industrial Revolution .GHGs of particular concern include carbon dioxide (CO2), nitrous oxide, methane, hydroflorocarbons and sulphur hexafluoride. Billions of tons of carbon in the form of carbon dioxide are absorbed by oceans and biomass and are emitted into the atmosphere naturally
Changes in land use and forestry practices can also emit carbon dioxide or act as a sink for carbon dioxide. Within the agricultural sector, nitrous oxide and methane are of primary concern; most of the other gasses are not typically associated with agricultural sources. Nitrous oxide is mainly emitted as a by-product of nitrification (i.e. aerobic transformation of ammonium to nitrate) and de-nitrification (i.e. anaerobic transformation of nitrate to nitrogen gas), which commonly occurs when fertilisers are used. Methane is emitted when organic carbon compounds break down under anaerobic conditions. These anaerobic conditions can occur in the soil, in stored manure, in an animal’s gut during enteric fermentation (mainly in ruminants) or during incomplete combustion of burning organic matter.
Several other gasses are also of interest because they may be converted into GHG, including nitrogen oxide, ammonia, non-methane volatile organic compounds and carbon monoxide.
Carbon Dioxide, Nitrous Oxide and Methane: Their Relationship with the Poultry Industry
Much of the carbon dioxide equivalent that the poultry industry generates is primarily from the utilisation of fossil fuels in the form of purchased electricity, propane use in stationary combustion units such as furnaces or incinerators, and diesel use in mobile combustion units such as trucks, tractors and generators that are used on the farm. In the animal industry, the consumption of plants (feed) by animals eventually results in the division of the carbon into either animal biomass (meat and eggs) or carbon dioxide respired by animals and fecal deposition of carbon in unutilised co-products (manure).
Aside from the fossil fuel emissions on poultry farms, nitrous oxide and methane gases are also emitted from manure during handling and storage. Nitrous oxide and methane emissions depend on management decisions about manure disposal and storage, as these gases are formed in decomposing manures as a by-product of nitrification / de-nitrification and methanogenesis, respectively. Stored manure will only emit nitrous oxide if nitrification occurs, which is likely to take place provided there is an adequate oxygen supply. Indirect GHG emissions of ammonia and other nitrogen compounds also occur from manure management systems and soils.
In animal agriculture, the greatest contribution to methane emissions is enteric fermentation (21 per cent) and manure management (eight per cent). Enteric fermentation is the most important source of methane in dairy production, while most of the methane from poultry and swine production originates from manure
Figure 4. Methane emissions from enteric fermentation in pounds (lbs.) based on animal type.
The figure represents emissions per animal per year.
Of course, one must consider the size (weight) of the livestock and the number of each type of livestock grown each year. Larger animals produce more methane than smaller animals. The amount of methane emitted increases with the number of animals grown. The type of digestive system will also determine the amount of methane produced. Cattle are poly-gastric animals with a four-compartment stomach. Their digestive tract is designed for microbial fermentation of fibrous material. One of the by-products of microbial fermentation is methane. Poultry and swine are monogastric animals with a simple stomach where little microbial fermentation takes place; therefore they produce less enteric methane.
Methane emissions may be generated as a result of the decomposition of manure under anaerobic conditions. These conditions occur readily when large numbers of animals are managed in a confined area. The main factor affecting methane emissions is the amount of manure produced and the portion of the manure that decomposes anaerobically. The amount of manure produced depends on the number of animals and the rate of waste production. Anaerobic decomposition depends on the type of manure storage. The majority of poultry production systems handle manure as a solid and the manure thereby tends to decompose under aerobic conditions, generating less methane than under anaerobic conditions.
The main cause of agricultural nitrous oxide emissions is from the application of nitrogen fertilisers and animal manures. Application of nitrogenous fertilisers and cropping practices are estimated to account for 78 per cent of total nitrous oxide emissions, according to Johnson et al., 2007. The EPA (2005) reported that manure from all livestock is a contributor to nitrous oxide emissions, with poultry accounting for nine per cent of manure nitrogen.
Nitrous oxide can be produced directly or indirectly through nitrification or denitrification of the nitrogen in the manure. Sixty-five per cent of all nitrous oxide emissions from stored manure result from soil microbial nitrification and denitrification. The loss of nitrogen from manure as gaseous emissions depends on how the manure is stored and applied to the land. Indirect emissions result from volatile nitrogen losses primarily in the form of ammonia and nitrogen oxide compounds. The amount of excreted organic nitrogen mineralised to ammonia during manure collection and storage depends on time and temperature. In the case of poultry, uric acid is quickly mineralised to ammonia nitrogen, which, due to its volatility, is easily diffused into the surrounding air. On the other hand, injecting or incorporating manure into the top layer of soil reduces ammonia emissions but can increase emissions of other nitrogen compounds.
How Can the Industry Address Carbon Footprints?
As the poultry industry moves toward becoming more energy efficient and sustainable, it is important to perform a complete evaluation of the carbon footprint of each segment of the poultry industry. Reducing poultry production’s carbon footprint will require identifying and adopting on-farm management practices and technological changes in production and waste management that can result in positive net changes for producers and the environment.
Reducing Fossil Fuel Use
Improvements in energy use on poultry farms have to be approached on an individual farm basis. Any savings in fossil fuel use will reduce emissions and thus the farm’s carbon footprint. There are a number of actions that can be taken to reduce the use of fossil fuel, specifically propane, on poultry farms, including:
- enclosing and insulating curtain openings in houses without solid walls to reduce heat loss and thus propane use
- installing attic inlets to allow the utilisation of the attic area as a solar energy collector
- adding insulation to the walls and ceilings to reduce heat loss
- installing circulatory fans to reduce temperature stratification and using radiant heaters instead of gas heaters for brooding
- choosing efficient exhaust fans for new buildings and replacing worn out fans in older/existing houses
- selecting energy-efficient generators and incinerators that will pay for themselves quickly with the amount of energy they conserve, and
- replacing incandescent lights with compact fluorescent lights to help reduce electricity use and costs.
Although many farms have already implemented some of these upgrades, there are still a number of poultry houses that have a lot of room for improving the efficiency of their heating systems and electricity use. It is not uncommon to see projected reductions of 40 per cent to 60 per cent. For more ideas on reducing energy use
Alternative Energy
Currently, there are a number of alternative energy sources that could be considered for poultry production. The most common are solar, wind and biomass. While these alternatives may eventually prove effective, they remain in the proving stage and are expensive to implement. Even though solar energy is readily available, it has a high cost of recovery when compared to fossil fuels. Wind energy is not as accessible as solar energy and is not practical in all areas. Biomass has a low power density and while it could not practically be used to power a poultry farm, it could be used to provide heat in poultry houses.
Alternatively, the litter in poultry houses could be used as renewable energy source, such as biomass for pyrolysis to produce liquid biofuels (which would be considered carbon-neutral) to power equipment on the farm. Replacing fossil-fuel energy with biofuel to operate equipment is considered carbon neutral because the contemporary carbon cycle produces and consumes this liquid fuel.
A co-product from biomass pyrolysis is bio-char, which can be used as a soil amendment that can sequester the carbon in soils for centuries. Bio-char has the capacity to reduce carbon dioxide emissions, thereby making the system carbon-neutral or in some instances carbon-negative.
Manure Management
Proper management of bedding and manure stores will reduce GHG emissions since substantial amounts of the methane and nitrous oxide are produced under sub-optimal conditions. Several factors affect methane and nitrous oxide emissions from manure, including temperature, moisture content and oxygen. Methane production from animal manures increases with increased temperature. This is where the majority of the methane is emitted during poultry production. The following mitigation strategies can help to reduce GHG emissions:
- handle manure as a solid or spread it on land where it decomposes aerobically and produces little or no methane
- avoid prolonged litter storage, which can increase methane emissions
- ensure manure heaps are covered to keep them dry
- add nitrification inhibitors to the poultry litter to reduce nitrous oxide emissions
- add high-carbon substrate to manure heaps, and
- compact solid manure heaps, which tends to reduce the oxygen entering the heap and therefore maintains an anaerobic condition in the heap. However, there is a drawback in that the anaerobic condition is favourable for methane production and one GHG would be swapped for another, i.e. reducing nitrous oxide but increasing methane emission.
What about Carbon Credits?
An international cooperation of 190 countries, including the United States, formed the Kyoto protocol, which has guided the global plan to reduce GHG emissions and invest in renewable technologies in developing countries. This global, compliance-driven market was valued at $120 billion in 2009 and estimates indicate that by 2020 it could be worth more than a trillion dollars.
From all indications, the majority of GHG gases generated by the poultry industry occur during the production stage (i.e. at the grow-out, pullet and breeder farms) and specifically come from propane and electricity use. It is therefore important that the poultry industry continues to work on improving efficiency when using fossil fuels in an effort to reduce GHG emissions. Engineering approaches will be necessary to address heating strategies and electricity use in poultry houses, and agricultural engineers and poultry scientists are constantly working on ways to make these houses more efficient. Through genetic selection and improved nutrition, the poultry industry has consistently improved growth rate and feed efficiency, and when compared to other animal production systems, the modern broiler, layer and turkey are considered to be very efficient. However, the scale of the Indian poultry sector is vast and even small impacts can add up; therefore, we must be vigilant and continue working to reduce emissions and make the industry more sustainable.
Climate Changes Opportunities for Poultry Farmers
Savings may be possible: winter energy costs may reduce as warmer winters reduce the need to heat buildings and flocks can be acclimatised outside. Locally grown soya and maize would cut feed costs and poultry ‘food miles’. Furthermore, meat products may increase in price and this – combined with feed prices possibly decreasing (due to the potential for soy yield to increase by 10 per cent as a result of rising carbon dioxide levels) – may make poultry farming more profitable.
Climate Changes Challenges
The challenges posed by climate change fit broadly into one of two categories: loss of productivity or increasing costs.
Regarding productivity, housing systems need to be managed to maintain optimal seasonal temperatures and reduce the risk of heat stress, and increased investment will be required in ventilation and cooling.
Reproductive capacity may decrease. Studies by the Department for the Environment, Food and Rural Affairs (Defra) on broiler hens found that a poultry house put under a future climate change scenario exceeded critical temperature on 30 per cent more occasions despite a 10 per cent increase in ventilation.
Furthermore, more dramatic events, such as storms, increase stress and may adversely affect productivity.
Costs are likely to increase as the result of the need to cool buildings more in summer and reduce house humidity. Building infrastructure and maintenance will have to cope with more intense weather events and increased rainfall. This means that building plans need to consider more sustainable options, with greater investment in drainage systems to accommodate more extreme and frequent floods and frequent rainfall.
Stocking density in the house may need to be reduced in extreme temperatures, and actively controlled ventilation could become essential in transportation vehicles.
Adaptation Suggestions
Poultry farmers should reconsider building design in new builds to more effectively cope with new climate and weather extremes, including the installation of more/new equipment to cope with new climate extremes.
Mitigating Measures
These include the installation of renewable energy – such as solar or wind power – to power poultry sheds, and using biomass boilers or anaerobic digestion of poultry litter.
Although some of the impacts might happen to a greater or lesser extent in the short, medium or longer term, it is important to think ahead for the future, especially in relation to issues such as building design.
Reducing energy use on the farm
From all indications, the majority of GHG gases generated from the poultry industry occur during the production stage (i.e. the grow-out, pullet and breeder farms), specifically propane and electricity use. The poultry industry continues to work on improving efficiency when using fossil fuels in an effort to reduce GHG emissions.
Improvements in energy use on poultry farms have to be approached on an individual basis. There are a number of actions that can be taken to reduce the use of fossil fuel, specifically propane on the poultry farms.
- For those houses that are not constructed with solid walls, enclosing and insulating curtain openings will reduce heat loss from the houses thereby reducing propane use.
- Installing attic inlets will allow the utilization of the attic area as a solar energy collector.
- Adding insulation to the walls and ceilings will reduce heat loss.
- Installing circulatory fans will reduce temperature stratification and using radiant heaters for brooding instead of gas heaters is not only more economical but is also more efficient.
- Energy efficient models of generators and incinerators should be selected as these will pay for themselves quickly with the amount of energy they conserve.
- Incandescent lights should be replaced with compact fluorescent lights to help reduce electricity use and costs.
Developing alternative energy sources
Currently, there are a number of alternative energy sources that could be considered, the most common are solar, wind and biomass. While these alternatives may eventually prove effective, they remain in the proving stage and are expensive to implement.
A considerable amount of poultry litter is generated annually in theIndia. A large amount of this litter is applied to crop lands and pastures as a means of soil amendment. The litter in poultry houses could alternatively be used as renewable energy source.
Reducing methane and nitrous oxide
Methane production from animal manures increases with increased temperature. This is where the majority of the CH4 emitted during poultry production. Prolonged litter storage can increase CH4 emissions and should be avoided when possible. To reduce the N2O emissions, nitrification inhibitors can be added to the poultry litter.
Genetic selection and nutrition
Other ways of becoming more efficient are through improving growth rate and feed efficiency. The poultry industry has consistently improved growth rate and feed efficiency through genetic selection and nutrition when compared to other animal production systems.
Reference-On Request
