Agriculture sector contributes 10-12 per cent of total GHG emissions from human activities directly. Additional indirect emissions that can be attributed to agriculture arise from fertilizer production, clearing of forest land and the use of fossil fuels in farm operations, storage and transport. Emissions directly associated with animal production have increased by about 1.1 per cent per year since 2000, linked to a steady growth in demand for animal products.
At the same time, the GHG emissions intensity of animal production (i.e. emissions generated on-farm for each kg of meat or per litre of milk produced) has decreased significantly (38% to 76% for various livestock products) from the 1960s to the 2000s. As demand for livestock is projected to continue to increase over the next decades in Pakistan, further reductions in emissions intensity are needed to limit the environmental burden from food production while ensuring sufficient supply of high quality, protein-rich food for a growing world population.
Emissions intensities currently vary widely within and across geographic regions and production systems, by a factor of two to more than four, especially for products from ruminant animals (meat and milk) but also for pork and poultry. Intensive animal production systems tend to have higher overall GHG emissions, but their emissions intensity is lower than in low-yield extensive systems. The gap between high and low emissions intensity producers in itself signals significant mitigation opportunities.
Pakistan is a major victim of global climate change (16th among 170 nations of the world) although it contributes very little to the global greenhouse gas emissions. It is ranked 135 among the countries of the world on the basis of per capita GHG emissions. Reducing emissions intensity on-farm will not necessarily translate into lower absolute emissions, as these depend on total production and responses of farmers to wider market and policy signals.
Emissions of GHGs in livestock systems imply losses of nitrogen, organic matter and energy, decreasing the overall efficiency of the sector. Increasing overall productivity and efficiency of farm systems, and recovering energy and nutrients, are key strategies to reduce the emissions intensity of livestock systems. The main drivers for this increased efficiency are generally economic benefits and increased resource utilization, with reduced GHG emissions intensity usually being an indirect benefit. Such existing trends can be accelerated by the increased adoption of current best practice across a wider number of farms which elevates average productivity and efficiency.
KEY OPPORTUNITIES FOR IMMEDIATE ACTION
Currently, four key available approaches for reducing on-farm livestock GHG emissions intensity are: two options specific to ruminants (improving feed quality/digestibility, and precision farming) and two options that are applicable to both ruminant and mono-gastric animals (improving animal health and husbandry, and manure management). Note that for specific farm systems and contexts, other specific mitigation options may also be effective and relevant. In addition, improving overall energy efficiency is a general and often cost-effective option, but reductions of total on-farm emissions are generally small except in some intensive and industrial-scale production systems, or when coupled with on-farm biogas production and energy generation.
A) IMPROVING FEED QUALITY AND DIGESTIBILITY
Low-quality and low-digestibility feeds result in relatively high enteric emissions per unit of meat or milk, particularly in systems with low productivity. Improving feed digestibility and energy content, and better matching protein supply to animal requirements can be achieved through better grassland management, improved pasture species, changing forage mix and greater use of feed supplements to achieve a balanced diet, including cropping by-products and processing of crop residues. These measures can improve nutrient uptake, increase animal productivity and fertility, and thus lower emissions per unit of product, but care needs to be taken that emissions from off-farm production of supplementary feeds and/or processing do not outweigh any on-farm reductions.
B) IMPROVING ANIMAL HEALTH AND HUSBANDRY
Increasing herd and animal efficiency can be achieved by improving herd and animal health management, extending the productive life of animals, and improving reproduction rates to reduce the number of animals kept for herd maintenance rather than production. Reducing the prevalence of common diseases and parasites would generally reduce emissions intensity as healthier animals are more productive, and thus produce lower emissions per unit of output. However, the mitigation potential from health interventions remains poorly quantified, largely due to limited disease statistics and barriers to the adoption of existing disease control mechanisms. Education and availability of efficient animal health diagnostic tools and therapeutics are a key part to improve animal (and human) health. These measures can increase productivity, reduce mortality rates, and reduce the age of first reproduction and replacement rates.
C) MANURE MANAGEMENT: COLLECTION, STORAGE AND UTILIZATION
Manure collection and storage is often poor and valuable resources contained in manure are lost. Improved manure storage facilities – with proper floors and coverage to prevent run-off to the surrounding environment – and customized technologies to apply manure would enhance production of food and feed crops. In addition, improved manure storage improves the hygienic conditions for animals and humans and enables the recycling of nutrients. Feeding a balanced diet to meet animal protein needs strongly influences manure composition and, depending on existing limitations or surplus of nitrogen in the feed supply, can reduce manure emissions and/or improve animal productivity. Biogas capture and utilization from manure ponds can provide a cost-effective low-carbon energy source and support energy access in remote rural areas, depending on herd size, housing system and initial capital investment costs.
D) PRECISION LIVESTOCK FARMING
Precision livestock farming caters for the individual animals needs in bigger herds, integrating health, genetics, feed, social behaviour and resource use and availability, which can be supported by sensor technology integrated in monitoring systems. Precision application of fertilizer and irrigation, aided by remote sensing of soil moisture, pasture growth and quality, can improve resource use efficiency. Precision livestock farming thus builds on and extends the individual approaches of optimizing feed quality and digestibility, and animal health and husbandry. For some farms, reducing overstocking can deliver higher quantity and quality of feed and health care and thus increase productivity of individual animals, which can maintain overall farm profitability while reducing absolute emissions and emissions intensity.
The authors are associated with the Agro-Climatology Lab, University of Agriculture, Faisalabad, Pakistan.