Abstract: Livestock production is one of the important emission sources of greenhouse gases (GHGs), evaluation of the carbon footprint of livestock products is vital for selection of mitigation technology and promotion of low-carbon agriculture. Based on current evaluation methods of carbon footprint, this study summarized the domestic and overseas researches on assessment of the carbon footprint of animal products (eggs, pork, beef and milk), and made a comprehensive analysis based on the present research achievements. Carbon footprint of livestock products varies with unit of animal products. The carbon footprint in producing 1 kg of beef is the greatest and reaches (20.51±8.39) kg CO₂-eq, followed by 1 kg of pork and eggs production with (4.24±1.07) kg CO₂-eq and (2.24±0.83) kg CO₂-eq, respectively, while that in producing 1 kg milk is the minimum of (1.19±0.40) kg CO₂-eq. The carbon footprint in producing 1 kg protein from animal products is in a descending order as beef＞milk＞pork and egg, with values of (103.05±42.14), (39.72±13.20), (32.09±8.14) and (19.37±7.15) kg CO₂-eq, respectively. The carbon footprint in producing 1 kg fat from animal products is in a descending order as beef＞milk＞egg and pork, with values of (488.25±199.65), (37.23±12.37), (29.28±10.80) and (11.45±2.91) kg CO₂-eq, respectively. The carbon footprint of 1 000 kcal energy from animal products are beef, milk, egg and pork in descending order, with values of (16.41±6.71), (2.21±0.73), (1.56±0.57) and (1.07±0.27) kg CO₂-eq, respectively. Analyses on different links of animal products revealed that the share of greenhouse gas emissions reaches maximum in feed crop planting and producing & processing during egg and pork production, accounting for (74.0±16.5)% and (61.3±7.6)%, respectively. The methane emission from enteric fermentation delivers the greatest contribution to carbon footprint during beef and milk production, accounting for (53.7±8.2)% and (52.7±6.1)%, respectively. Analyses on GHGs emissions from animal products showed that CO₂ contributes the maximum to the carbon footprint during egg production, whose emission covers (55.42±2.7)% of the entire system. N₂O contributes the maximum during pork production, with (56.8±10.4)% of the entire system. CH₄ contributes the maximum during beef and milk production, with (50.2±8.3)% and (58.6±8.3)%, respectively. Although researches on carbon footprint of livestock products based on different methodologies are mostly in abroad, unified assessment guidance needs to be developed to evaluate the carbon footprint of livestock products. There is little research on carbon footprint in China, so it’s suggested that an assessment method suitable for actual production in China should be established. The result of this study could provide some preliminary data to the assessment of carbon footprint of livestock product and identification of mitigation options.

Key words: animal, greenhouse gas, carbon footprint, assessment method