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Considering all energies involved in a livestock farming system

Future doubling in world demand for dairy products requires the design of more productive and sustainable systems in different regions of the world. The efficiency of using fossil energy becomes is a major challenge due to strong dependence of the industrialized livestock sector to fossil energy resources and greenhouse gas emissions during its combustion. Moreover, its use tends to improve the conversion of solar energy by plants into biomass through mineral fertilization, and mechanization improves labor productivity by substitution for labor energy.

… on contrasted dairy sytems from four territories

With the aim to assess precisely the functioning and performance of different dairy systems, an original and generic method of pluri-energy analysis (Vigne et al., 2012) was developed and applied on contrasted dairy systems from four territories: smallholder dairy systems from arid areas (Mali), specialized dairy (Bretagne) and mixed crop-livestock systems (Poitou-Charentes) from temperate areas and intensive dairy systems from humid tropical areas (Reunion Island) (Vigne et al., 2013).

The pluri-energy analysis method is based on:

• an accounting of the four types of energy used in agricultural systems: solar, fossil (direct and indirect to produce inputs), gross energy contained in biomass, and physical energy expenditure during animal and human labor
• the representation of the system into productive and storage components
• the quantification of all energy flows entering the system, circulating among the components and leaving the system.

An efficient use of fossil energy variable due to socio-climatic factors

Low-input systems from Mali, primarily based on solar and labor energy types, require substantial fossil energy inputs to produce milk (0.1 MJ/L of milk). Farms from Bretagne and Poitou-Charentes show intermediate values of fossil energy use for milk production (respectively 3.6 MJ.l-1 and 4.9 MJ/L of milk) whereas farms on Reunion Island require a relatively large amount of fossil energy (6.6 MJ/L of milk). Factors explaining these differences are mainly related to specific socio-climatic conditions. In Mali, the major part of energy produced corresponds to manure from the herd (more than 80%) mainly used for crop fertilization.

Analysis of variability among farms shows that cow productivity could be improved up to 600 l per year (close to 6 times the production of traditional systems) without increasing fossil energy cost. These results counterbalance the general idea of a low efficiency of these systems in managing their resources, especially regarding their low productivity. In temperate areas, the efficiency of fossil energy use increases with the proportion of pasture in animal food. However, systems with maize silage that use more fossil energy, provide a secure forage supply even when facing variation in the climate. In Reunion Island, the willingness to maintain of a high level of local milk production, despite the lack of arable land, increases animal loading and import of feed concentrates (more than 4.5 tons per cow per year).

Toward an improvement of fossil energy use efficiency adapted

Improvement of fossil energy use efficiency is a key objective to develop productive and sustainable dairy systems. Beyond the assessment of agricultural systems functioning under different socio-climatic conditions, the pluri-energy analysis is of interest to assess the variability of livestock systems within a territory for designing improved ways of fossil energy utilization specific to local conditions.

For futher information

Vigne M., J. Vayssières, P. Lecomte, J.L. Peyraud. 2012. Evaluating the ability of current energy use assessment methods to study contrasting livestock production systems. J. Env. Manag. 112: 199-212. (DOI)
Vigne M., J. Vayssières, P. Lecomte, J.L. Peyraud. 2013. Pluri-energy analysis of livestock systems - a comparison of dairy systems in different territories. J. Env. Manag. 126: 44-54. (DOI)
Vigne, M., O. Martin, P. Faverdin, J.L. Peyraud. 2012. Comparative uncertainty analysis of energy coefficients in energy analysis of dairy farms from two French territories. J. Cleaner Prod. 37: 185-191. (DOI)
Vigne, M., Benagabou, I., Faverdin, P., Coulibaly, D., Ba, A., Vall, E., Kanwe, A., Blanchard, M., 2014. Évaluation de l’efficience énergétique fossile des systèmes d’élevage en Afrique de l’Ouest : adaptations et perspectives méthodologiques. INRA Prod. Anim. 27 (5), 369-380. (Lien) [in french]

Contact

Jean-Louis Peyraud et Philippe Faverdin, team dairy systems
jean-louis.peyraud[at]rennes.inra.fr ; philippe.faverdin[at]rennes.inra.fr