Rev Mex Cienc Pecu 2020;11(Supl 2):18-33
farms; the weighted EF per farm was similar (49.06 and 54.09, kg CH4 yr-1), but the LCH4 estimated using the IPCC equations was lower than that obtained through farm observations (1.11 and 1.97, Mcal d-1; P<0.01, respectively). In general, the use of technical information from the farms, made it possible to estimate the EF and to show a higher LCH4 per farm, and, consequently, a lower energetic efficiency, compared to the IPCC methodology. Key words: Stable, Subsistence production, Ruminal fermentation, Environmental contamination, Energy loss.
Received: 18/11/2017 Accepted: 27/08/2019
Introduction Dairy farming is very important for meeting the demand for high quality food for human consumption; however, it also contributes to the emission of greenhouse gases (GHGs) such as methane (CH4), which is produced by enteric fermentation and is eliminated mostly through the burp(1,2). CH4 is one of the main GHGs emitted by the systems of production of bovine cattle, which has been associated with the global warming and climate change, as evidenced by comparison with the pre-industrial era(1,2). The issued CH4 also contributes to the energy leaks in the livestock production systems, as it amounts to the loss of 6 to 12% of the total gross energy (GE) consumed by the dairy producing livestock(2). An important reference for estimating the CH4 production is the methodology proposed by the Intergovernmental Panel on Climate Change (IPCC)(3). This methodology is used in different countries in order to generate the inventories of GHGs, and applies the corresponding procedures depending on the information available at levels 1, 2 and 3. Level 1 (Tier 1) is applied to Mexico and other developing countries; it is based on the use of an emission factor (EF) of CH4 yr-1 animal-1 that is multiplied by the national inventory within each category of livestock. A criticism made to this methodology is that it employs an EF that in many situations does not represent the reality of the particular conditions of production, particularly with regard to the characteristics of the food consumed by the dairy cattle raised in different regions of the country, which varies according to the agro-ecological, environmental, economic and health characteristics(4.5).
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