A report by the United Nations Food and Agriculture Organization (FAO), estimates that 18 percent of annual worldwide green house gases emissions, are attributable to livestock viz: cattle, buffalo, sheep, goats, camels, horses, pigs and poultry that cause global warming. Globally the sector contributes 7.1 billion tones CO2 equivalent of global greenhouse gas emissions. Although it accounts for only 9 percent of global CO2, it generates 65 percent of human related nitrous oxide (N2O) and 35 percent of methane (CH4).
As far as Poultry sector is concerned it contributes both directly and indirectly to green house gases through the emissions of different gases viz: ammonia, carbon dioxide, methane, nitrous oxides well as dust, pathogens and other micro-organisms, which affect the quality of the air in the poultry house which ultimately has huge effect on the health of poultry birds, humans and the surrounding environment. Therefore it is important to control the emission of these harmful gases as low as possible so that it should not affect the health of birds, workers within the house as well as the environment.
There are so many reasons for the production of these gasses in commercial poultry farm. The majority of green house gases emissions generated from the house are because of poor management in poultry house, mainly over crowding, excess wetting of litter material, unorganized ventilation system, air temperature, air movement above the litter surface, air penetration through the litter, litter temperature, humidity, moisture, pH, feed composition and manure handling practices in the poultry farms along with feed production and from the breakdown of fecal matter, which results in the production of these hazardous gases. Following are the some important green house gases.
Harmful Gases generated from poultry house:
Ammonia:
Ammonia (NH3) is one of the important gas produced in the poultry farm. It is generated mainly during bacterial decomposition of protein and urea under aerobic and anaerobic conditions. Besides this other reasons are like, wet litter, humidity, improper ventilation, poorly maintained water in drinkers, high bird stocking density and flocking behavior. The amount of ammonia emissions increases in advance stage of birds and with the age of litter, which leads to the reduction in the feed intake and poor bird weight gain, decreased egg production as well as egg quality, damages the respiratory tract. It also increases the susceptibility of bacterial and viral diseases. According to one report the average ammonia emission rate per bird was 19.7 and 18.1 mg. h–1 in the summer and winter, respectively (Calvet al., 2011).
Methane:-
Chickens release negligible amount of methane during their digestion process. Methane emissions are all associated with poultry house. Droppings of chickens contributes to generation of atmospheric methane especially when decomposition of the fecal matter occur sunder the anaerobic condition and manure application. Its production increases with increase in temperature. As per the report the average CH4 emissions was found 0.44mg.h-1 per bird in summer and 1.87 mg.h-1 per bird in winter(Calvetet al., 2011).
Nitrous oxide
Gaseous nitrogen compounds are known to cause severe environmental problems. Nitrous oxide (N2O) is a very potent greenhouse gas, The non-ruminant sector is a minor N2O emissions contributor compared with ruminant N2O emissions. The poultry industry is the largest direct N2O producer of the non-ruminant livestock industries, contributing 92.8% of the total non-ruminant N2O emissions (Toit Du C.J.L et al., 2013). The production of N2O from poultry manure depends on feces composition, microbes and enzymes involved and the conditions after excretion. Average N2O emissions was found 1.74 and 2.13 mg.h-1 per bird in summer and winter, respectively(Calvetet al., 2011). It was found that daily emission of 46 mg N2O per chicken and for whole 60 days period 2.8 kg per bird (Medaet al., 2011) The actual rate of N2 O emission is highly dependent on the management strategies implemented on a farm.
Carbon dioxide
Production of CO2 is mainly due to the use of heating material especially propane in broiler and pullet houses during brooding and cold weather. However it is also seen that major part of CO2 seemed to have its origin from bird respiration with assumed production of approx. 147 kg of CO2.h-1. CO2 emission was most affected by chickens towards the end of the fattening period taking dominance over the process of natural gas burning by heaters. The mean CO2 emission from the chicken house ranged between 120 and 247 kg.h-1 in the first quarter of periods and between 325 and 459kg.h-1 in the last ones. After the evaluation of CO2 emission rates were 3.84 and 4.06 g.h-1 per bird in summer and winter, respectively(Calvetet al., 2011).
Remedies:
The goal for most of the poultry producers is either to avoid, to control or to minimize the gases production in poultry house so that to avoid its impacts on bird health and performance. There are some important measures which can help to reduce the emission of green house gases to some extent from poultry house.
Primary action is to modify poultry housing on scientific lines, efficient management of litter material used and proper handling and disposal manure. The levels of gases in poultry housing have been closely associated with manure management. The increase in manure organic content raises N2O emissions. Separation of manure solids lowers the organic content of liquid manure, which generally results in lower emissions of N2O. Reducing dietary protein by 3-5% may cause a reduction of 60% or more in total nitrogen excretion from broilers and laying hens.
Diet management is important to control ammonia production in poultry house, so proper provision of a balanced and complete diet is of the highest importance to prevent ammonia production and increases broiler performance and feed efficiency. A well-balanced diet contains highly digestible ingredients and functional feed additives that can improve the digestibility of nutrients in the small intestine of birds.
Proper stocking density is important to limit excessive moisture in the poultry house by maintaining the proper ventilation for minimal production of ammonia. However, this should only be in accordance with the climate and temperature of the poultry house. Proper handling and disposal of poultry manure which includes litter material is also help to reduce the generation of harmful gases. Scientific housing and feeding management is very important to combat this problem. Poultry owners must continually seek advances in housing technology to improve indoor air quality of their farms.
References:-
1. Calvet, S., Cambra-Lopez, M., Estelles, F. & Torres A.G. (2011). Characterization of gas emissions from a Mediterranean broiler farm. Poult. Sci., 90, 534–542. DOI: 10.3382/ps.2010-01037.
2. Meda, B., Hassouna, M., Flechard, C., Lecomte, M., Germain, K., Picard, S., Cellier, P. & Robin P. (2011). Housing emissions of NH3, N2O and CH4 and outdoor emissions of CH4 and N2O from organic broilers. In J. Kofer& H. Schobesberger (Eds.), Proceedings of the XVth International Congress of the International Society for Animal Hygiene (pp. 215−218). Tribun, EU.
3. Toit Du C.J.L., Van Niekerk W.A., Meissner H.H. Direct Methane And Nitrous Oxide Emissions Of Monogastric Livestock In South Africa. South African Journal Of Animal Science 43, 362, 2013.
Dr Nazir Ahmed1, Dr Malik RaiesUl Islam2DrAijaz A Dar3 and Dr Mir Rovida4
1Scientist Animal Science KVK-Kupwara, SKUAST-K
2Scientist Animal Science KVK-Srinagar, SKUAST-K
3Assistant Professor, Veterinary Medicine, SKUAST-K
4Guest Lecture Division of LPT-F.V.Sc. and A.H-SKUAST-K
Corresponding Author: -animaldr2@gmail.com
