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Efficiency of extensive livestock systems in harsh environments

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The livestock sector will need to provide meat and milk for a growing population, while at the same time limiting its environmental impacts. To meet this challenge, more and more studies are being conducted to identify the most efficient systems from an environmental perspective, especially those that use the fewest nonrenewable resources in relation to their output. In 2006, an FAO report thus called attention not only to the environmental damage they cause, but also to the lack of efficiency of livestock systems, especially extensive systems in developing countries, whose level of food production remains low. Questioning this report, a recent study conducted by CIRAD in four different régions shows that extensive dairy systems in Mali can be more efficient than intensive systems in Reunion Island, and just as efficient as semi-intensive systems in western France. This result was obtained using the emergy methodology, which uses one type of unit to evaluate all the resources consumed to generate food or non-food products. This methodology takes into account the complex and multifunctional nature of livestock systems, especially extensive ones. Emergy could be a useful tool enabling decision-makers to develop livestock policies adapted to suit individual contexts, and to thereby meet the growing demand for livestock products.
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Nitrogen (N) is one of the most limiting factors in West African crop-livestock systems. This study shows the first results of N cycling analysis in systems integrating zebu breeding and pearl millet growing in the Senegalese groundnut basin. The whole N flows have been reconstituted thanks to a four farms monitoring on the march – august period in 2015. On-farm monitoring means that existing systems, based on local practices, have been studied unlike on-station experimentations. The goal of the study device is to compare three systems i) a traditional one (SysT) based on day free-grazing and night corralling on millet fields, ii) an intensive system (SysI) where cattle is fattened in barns on the basis of feed concentrates, producing solid manure used to fertilize millet crops and iii) an improved intensive system (SysIA) corresponding to the previous one but with additional practices aiming a better nutrient (manure covering and in-soil manure incorporation). The study allows to compare N inflows and outflows at each step of the production cycle (Animal, Manure and Soil-Crop steps). Three indicators are calculated at each cycle step and for the whole cycle: i) the agronomic N use efficiency (ENA) or the recycling rate, ii) the edible N use efficiency (ENC) or the exportation rate and iii) the global N use efficiency (ENG) which is the sum of the previous two ones. For the SysT, Animal step is characterized by a very high ENA (155%) linked with a negative ENC because of the loss of livestock body weight during the dry season. On the contrary, SysI and SysIA show an ENC of +19% related to an important body weight gain in these systems. The Manure step (which not exists in SysT) shows important gaseous loses, limiting ENA at 61% for SysI. Manure covering leads to an ENA of 76% for SysIA. Plant ability to mobilise soil N resources is source of an ENG higher than 100% for the Soil-Crop step (172 ant 191% for SysT and SysIA respectively). Manure incorporation, tested in SysIA allows to multiply by 3.6 manure effectiveness (compared to SysI). About the whole N cycle, SysT have shown a low ENC (24%) but a high ENA (209%). Otherwise, SysI proved a high ENC (87%) but a limited ENA (61%). Finally, SysIA appears as a good compromise with ENC and ENA of 90 and 85% respectively. Overall, SysT stays the most efficient. However in next decades, an extension of SysI is expected to face the growing meat demand in Senegalese large cities. This system causes important N loses to the environment which can be mitigated by improved practices proposed in SysIA at the Manure and Soil-Crop steps. (PDF) Suivi du cycle de l’azote en fermes réelles - Cas des systèmes agropastoraux du bassin arachidier du Sénégal. Available from: https://www.researchgate.net/publication/292985885_Suivi_du_cycle_de_l'azote_en_fermes_reelles_-_Cas_des_systemes_agropastoraux_du_bassin_arachidier_du_Senegal [accessed Oct 31 2019].
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This paper introduces a generic assessment method called pluri-energy analysis. It aims to assess the types of energy used in agricultural systems and their conversion efficiencies. Four types of energy are considered: fossil energy, gross energy contained in the biomass, energy from human and animal labor and solar energy. The method was applied to compare smallholder low-input dairy-production systems, which are common in developing countries, to the high-input systems encountered in OECD countries. The pluri-energy method is useful for analyzing the functioning of agricultural systems by highlighting their modes of energy management. Since most dairy systems in South Mali (SM) are low-input systems, they are primarily based on solar and labor energy types and do not require substantial fossil-energy inputs to produce milk. Farms in Poitou-Charentes (PC) and Bretagne (BR) show intermediate values of fossil-energy use for milk production, similar to that found in the literature for typical European systems. However, fossil-energy use for milk production is higher on PC than BR farms because of a higher proportion of maize silage in the forage area; grazing pastures are more common on BR farms. Farms on Reunion Island (RI) require a relatively large amount of fossil energy to produce milk, mainly because the island context limits the amount of arable land. Consequently, milk production is based on large imports of concentrated feed with a high fossil-energy cost. The method also enables assessment of fossil-energy-use efficiency in order to increase the performance of biological processes in agricultural systems. Comparing the low-input systems represented by SM to the high-input systems represented by RI, PC and BR, an increase in solar-energy conversion, and thus land productivity, was observed due to intensification via increased fossil-energy use. Conversely, though fossil-energy use at the herd level increased milk productivity, its effect on gross-energy conversion by the herd was less evident. Partitioning the total on-farm gross energy produced among animal co-products (milk, meat and manure) highlights the major functions of SM herds, which are managed to produce organic crop fertilizers.
Article
Emergy accounting (EmA) was applied to a range of dairy systems, from low-input smallholder systems in South Mali (SM), to intermediate-input systems in two regions of France, Poitou-Charentes (PC) and Bretagne (BR), to high-input systems on Reunion Island (RI). These systems were studied at three different levels: whole-farm (dairy system and cropping system), dairy-system (dairy herd and forage land), and herd (animals only). Dairy farms in SM used the lowest total emergy at all levels and was the highest user of renewable resources. Despite the low quality of resources consumed (crop residues and natural pasture), efficiency of their use was similar to that of industrialised inputs by intensive systems in RI, PC and BR. In addition, among the systems studied, SM dairy farms lay closest to environmental sustainability, contradicting the usual image of high environmental impact of cattle production in developing countries. EmA also revealed characteristics of the three intensive systems. Systems from RI and PC had lower resource transformation efficiency and higher environmental impacts than those from BR, due mainly to feeding strategies that differed due to differing socio-climatic constraints. Application of EmA at multiple levels revealed the importance of a multi-level analysis. While the whole-farm level assesses the overall contribution of the system to its environment, the dairy-system level is suitable for comparison of multi-product systems. In contrast, the herd level focuses on herd management and bypasses debates about definition of system boundaries by excluding land management. Combining all levels highlights the contribution of livestock to the global agricultural system and identifies inefficiencies and influences of system components on the environment.
Article
Emergy is defined as the direct and indirect energy available to make a product or a service. Emergy accounting is a quantitative technique that determines non-monetary and monetary values of resources, services and products in a common unit: solar Emergy. This method appears suitable to assess agroecosystems and identify key factors for designing more sustainable systems. This article discusses the concept of Emergy through the definition of transformity, energy-system diagrams and several Emergy indicators. These concepts are explained through an example of a fish-farming system assessment. Finally, the article underlines the possible applications of emergy accounting to agricultural systems, in particular animal production.
Livestock's Long Shadow
  • H Steinfeld
  • P Gerber
  • T Wassenaar
  • V Castel
  • M Rosales
  • C De Haan
Steinfeld H., Gerber P., Wassenaar T., Castel V., Rosales M., de Haan C., 2006. Livestock's Long Shadow. Environmental Issues and Options. FAO, LEAD initiative, Rome, Italy.
Flux d'énergie dans des systèmes d'élevage laitiers contrastés : élaboration d'indicateurs et analyse de la diversité inter et intraterritoire
  • M Vigne
Vigne M., 2012. Flux d'énergie dans des systèmes d'élevage laitiers contrastés : élaboration d'indicateurs et analyse de la diversité inter et intraterritoire. Thèse de doctorat en sciences agronomiques, Agrocampus Ouest, Rennes, France. 269 p. http://prodinra.inra.fr/record/217153