Introduction
As per DAHD annual report 2021, India has an estimated milk production of 198.44 million tonnes during 2019-20 with growth of 5.69 % compared to previous year (DAHD annual report 2021).Livestock contributes to climate change through emission of methane, nitrous oxide and carbon dioxide and land use changes. Livestock contributes greenhouse gas emissions around 7.1 Gt CO2e per year (FAO, 2006) which is around 14.5% of the world’s greenhouse gas emissions. Greenhouse gas emissions from dairy production systems account for 2.13 Gt of CO2e per year which is 30% of the emissions from livestock (Gerber et al., 2013). Research shows there is widegap in intensive and extensive dairy system in terms of its GHG emission due to difference in the enteric methane, and nitrous oxide emissions from the dung of animal.
Dairy farming systems
With respect to dairy farming there are three different farming systems:
- Intensive– In intensive farming system, farmers bring and provide water and chopped or cut grass to their cattle in a paddock.
- Semi-intensive– Cattle of semi-intensive farming get their feed by themselves from pastureland in morning and are stallfed during rest of the day.
- Extensive– Cattle of this farming graze freely on pasture land, and they do not need extra feed in general condition. Animals are tied only in harsh condition.
In free-range systems, livestock may overgraze land, resulting in desertification, and pollution of water sources. Intensive farming systems can cause problems due to manure management, including: pollution, insect, dust, and odour. Overgrazing, with eventual soil erosion, habitat degradation and desertification, is cited frequently as an ecological problem throughout the world.
| FARM | OBSERVATION | REFERENCE |
| Organic, free range and conventional | Climate change, acidification and eutrophication have lower values in free-range and organic systems, compared to conventional system | Haas et al.,2001 |
| Organic and conventional | Organic -lower energy use and eutrophication potential.Acidification potential and globalwarming potential were similar for both systems | Thomassen et al., 2008 |
| Intensive dairy farm (New Zealand) | Intensification reduced dairy farm eco-efficiency | Basset-Mens et al., 2009 |
| Alpine dairy farms | Best environmental performances by farms having low stocking density, low production intensity, and large land availability | Penati et al., 2011 |
Environmental impact of dairy farm intensification
To meet growing demands of milk and milk based products for human consumption, there have been efforts of intensification of dairy farming systems. However, with large scale intensification of dairy cattle production system, environmental side-effects became visible.
Animal manure is an environmental hazard due to its high concentration of nitrate, phosphate, potassium and ammonia. NH3 contributes to eutrophication and acidification when redeposited. This eventually results in leaching of nitrate and phosphate contribute to nutrient water enrichment; contributed to declining ecological quality of water.
| Emissions | Estimates | Reference |
| Enteric CH4 emission estimate | 14.3 Tg/year for the year 2010 | Patra , 2014 |
| Enteric CH4emission prediction | 15.8 Tg/year and 18.8 Tg/year by 2025 and 2050 respectively |
The most important GHGs that are emitted from dairy supply chain are carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O) and to a lesser extent hydrofluorocarbons (HFCs).
The greenhouse gas emissions from livestock are mostly on farm (72%) and off farm emissions (28 %) are less comparatively. The on-farm sources of emissions included: Cow – 25% as enteric CH4
- Manure – 24% as CH4 and N2 O
- Field – 19% as N2O and CO2
- Farm energy – 4% as CO2
To plan for reducing harmful effect on environment, we must first know the negative impact. Environmental impact of dairy cattle production systems can be assessed by indicators derived from
- Input-Output Accounting (IOA) – process oriented on-farm method frequently used to assess nutrient surpluses of agricultural production systems
- Ecological Foot Print analysis (EFP)- the amount of resources consumed
- Life Cycle Assessment (LCA)
EFP and LCA are life cycle based methods. Life cycle based methods evaluate global emissions and impacts from the entire production chain (life cycle), in relation to types and amounts of products produced. LCA indicators appeared to be most effective, because of their high relevance, good quality and the fact that they focus on more than one environmental aspect and take into account pollutants throughout the production chain.
Strategies to reduce the environmental burden
- Ration Balancing approach can provide promising results in reducing enteric methane emission from cows and buffaloes
- Increasing the quality of feed, especially roughage, can reduce enteric CH4 production
- Optimizing protein feeding can result in reduction of nitrogen emission
- Elimination of non-milking animals could also reduce emissions
- Higher recycling of manures and better integration of livestock in farming systems can lead to reductions in chemical fertilisers and reductions in losses from nitrogen and phosphorus.
- Monitoring of various hotspots can help reduce the negative environment impact
Conclusion
The environmental impact of livestock is one of the main constraints to the development of livestock sector; vary with the system of dairy farming since intensification increases the environmental load per unit area. So, it is better to optimize the level of production and reduce the environmental impact by feeding animals on the mixture of extensive and intensive systems. High yielding animals or animals with higher growth rate cannot be sustained on the extensive system alone. GHGs emitted from the dairy production are carbon dioxide, methane, nitrous oxide and to a lesser extent hydrofluorocarbons (HFCs) ; 72% are on farm.
Komal Chauhan, Bilal Chamadia and Rashika Srivastava
PhD Scholar, Division of Animal Nutrition, ICAR-National Dairy Research Institute, Karnal-132001
e-mail: chauhankomal603@gmail.com
