Abstract
Greenhouse gas emissions from livestock farming and in particular enteric methane (CH4) from ruminants are criticized for being one of the main contributors to climate change. Different breeding, feeding and management strategies are tested to decrease these emissions, but a status quo analysis is also relevant to implement such measures. The present study aimed to analyze the concentration of CH4 in air exhaled by dairy cows along a rural-urban gradient of Bangalore, India. Urban, mixed and rural areas were defined based on a survey stratification index (SSI) comprising build-up density and distance to the city center. Using a laser methane detector (LMD), CH4 concentration was determined in 2-min spot measurements of exhaled air of 448 cows at three equally spaced visits between June 2017 and April 2018. Mean, maximum and CH4 concentration per duration of the overall measurement, eructation and respiration bouts were calculated. For the overall mean and respiration bouts, CH4 concentration was higher in cows from urban areas, which had also higher milk yield than cows from mixed and rural areas. Although no differences were found in terms of the intake level of fibrous diet components, the type of measurement location (indoor, half-outdoor or outdoor) and pasture access had an impact on CH4 concentration. To our knowledge, this is the first study using the LMD on-farm and in an urbanizing environment. The LMD measurements show variations in enteric CH4 emissions along the rural-urban gradient of Bangalore that reflect differences in dairy husbandry systems governed by the social-ecological context.
Highlights
In the past 30 years, world milk production has increased by more than 52% from 542 million tons in 1990 to 828 million tons in 2017
greenhouse gas (GHG) emissions are expected to increase by 35% until 2050, especially in developing countries due to animal population growth driven by increased demands of meat and dairy products [8]
We found a higher percentage of native dairy cows in urban and mixed than in rural areas (Table 1)
Summary
In the past 30 years, world milk production has increased by more than 52% from 542 million tons in 1990 to 828 million tons in 2017. India has tripled its milk production from 54 to 176 million tons, becoming the world’s largest milk producer with 21% of the global production [1]. India hosts 18% of the global dairy cattle population [1]. Urbanization in India has increased rapidly and the share of urban population has doubled in the past 60 years [4]. Urban and (peri-)urban agriculture have contributed to food security and covered the demand for food products in these areas, e.g., with regard to milk consumption, by keeping dairy cattle close to urban areas [5]. GHG emissions are expected to increase by 35% until 2050, especially in developing countries due to animal population growth driven by increased demands of meat and dairy products [8]
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