Improving feed efficiency increases animal productivity per unit of feed, may increase farm profitability
Photo: iStock About 32 per cent of global anthropogenic methane emissions result from microbial processes that occur during the enteric fermentation of ruminant livestock and manure management systems, while another 8 per cent comes from rice paddies, a new report showed. To tackle this, the Food and Agriculture Organization (FAO) of the United Nations suggested four strategies (discussed later) for better management of livestock.
Methane emissions in livestock and rice systems: Sources, quantification, mitigation and metrics published by FAO on September 25, 2023 focuses on both the sources and sinks of methane gas, outlines how emissions can be measured, describes a broad sampling of mitigation strategies and evaluates the kind of metrics that can be used to measure both emissions and their mitigation on the climate system.
Methane is a short-lived greenhouse gas (GHG), which has an atmospheric lifetime of around a decade, as against the dominant GHG carbon dioxide, which affects the climate for hundreds of years. However, methane is more than 25 times as potent as carbon dioxide at trapping heat in the atmosphere.
“Because of this difference in their respective lifetimes, the GHG emission metrics used to compare methane with carbon dioxide vary depending on what time frame they consider,” said the report.
It, however, pointed out that measuring methane emissions and inventories is tricky and that appropriate quantification and reporting of GHG emissions, specifically methane, is important for mitigation.
While precise methods have been developed, often involving placing animals in respiration chambers, they are expensive, labour-intensive and difficult to apply to grazing animals. “Sophisticated use of drones and satellites has been deployed, but this approach entails much modelling and research is lagging behind in validating these methods,” FAO said.
The report, put together by a multidisciplinary team composed of 54 international scientists and experts of the Livestock Environmental Assessment and Performance Partnership, was released during FAO’s first ever ‘Global Conference on Sustainable Livestock Transformation’ from September 25-27, 2023.
The Sixth Assessment Report of the Intergovernmental Panel on Climate Change had found that methane emissions from all anthropogenic activities currently contribute about 0.5 degrees Celsius to observed global warming, making their reduction an important pathway to achieve the Paris Agreement.
Besides agrifood systems, other human activities that generate methane emissions include landfills, oil and natural gas systems, coal mines and more.
Among ruminants, the highest daily emitters on a per animal basis are cattle, followed by sheep, goats and buffalo.
Meat and milk from ruminant livestock provide an important source of protein and other nutrients for human consumption. By 2050, the global demand for animal products is projected to increase by 60-70 per cent, with developing countries accounting for the majority of this increase.
The study noted four broad strategies in mitigating methane emissions: i) Animal breeding and management; ii) Feed management, diet formulation and precision feeding; iii) Forages and iv) Rumen manipulation.
In the recent past, there has been a lot of discussion about feed improvement for reducing absolute methane emissions and the report also talked about improving feed efficiency, which is defined as the ratio of animal product to feed intake (kilogram of meat or milk per kilogram dry matter intake), in reducing methane emission intensity.
“Feed efficiency may be improved by increasing the nutrient density or feed digestibility, altering the rumen microbial composition, enhancing feed management practices and selectively breeding for animals with negative residual feed intake (difference between animal’s actual intake and expected) and smaller metabolic body weight, or a combination of the above,” it said.
Improving feed efficiency increases animal productivity per unit of feed and may increase farm profitability depending on the cost of feed with respect to the revenues from meat and milk.
It highlighted the importance of studies quantifying the effects of improved nutrition, health, reproduction and genetics to increase animal production and decrease methane emission intensity on a regional basis so that these measures are relevant and can be implemented.
“There is a lack of information required to calculate carbon footprints of interventions on a regional basis, which would make it possible to evaluate the impact of mitigation strategies on net GHG emissions. Economically affordable enteric methane mitigation solutions are also in short supply,” the authors of the report noted.
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