Agroecology and industrial ecology can be viewed as complementary means for reducing the environmental footprint of animal farming systems: agroecology mainly by stimulating natural processes to reduce inputs, and industrial ecology by closing system loops, thereby reducing demand for raw materials, lowering pollution and saving on waste treatment. Surprisingly, animal farming systems have so far been ignored in most agroecological thinking. On the basis of a study by Altieri, who identified the key ecological processes to be optimized, we propose five principles for the design of sustainable animal production systems: (i) adopting management practices aiming to improve animal health, (ii) decreasing the inputs needed for production, (iii) decreasing pollution by optimizing the metabolic functioning of farming systems, (iv) enhancing diversity within animal production systems to strengthen their resilience and (v) preserving biological diversity in agroecosystems by adapting management practices. We then discuss how these different principles combine to generate environmental, social and economic performance in six animal production systems (ruminants, pigs, rabbits and aquaculture) covering a long gradient of intensification. The two principles concerning economy of inputs and reduction of pollution emerged in nearly all the case studies, a finding that can be explained by the economic and regulatory constraints affecting animal production. Integrated management of animal health was seldom mobilized, as alternatives to chemical drugs have only recently been investigated, and the results are not yet transferable to farming practices. A number of ecological functions and ecosystem services (recycling of nutrients, forage yield, pollination, resistance to weed invasion, etc.) are closely linked to biodiversity, and their persistence depends largely on maintaining biological diversity in agroecosystems. We conclude that the development of such ecology-based alternatives for animal production implies changes in the positions adopted by technicians and extension services, researchers and policymakers. Animal production systems should not only be considered holistically, but also in the diversity of their local and regional conditions. The ability of farmers to make their own decisions on the basis of the close monitoring of system performance is most important to ensure system sustainability.
We present a novel application of Bayesian procedures to assess the impacts of logging rain forest on birds and small mammals in tropical Queensland, Australia, using data from a 1983‐1986 BACIP (measures made before and after on control and impact sites) study. The procedure was compared with the usual approach to the analysis of BACIP designs following the methods of Stewart‐Oaten et al., which are based on classical Neymann‐Pearson significance testing. Significance tests were performed at the 0.05 and 0.1 levels, power being calculated for a 25% reduction in species capture rates. For the Bayesian analysis, we elicited one noninformative and three informative prior distributions representing polarized beliefs about the effect size of logging: a strong negative effect, little or no effect, and an effect related to the amount of canopy loss. Effect size was estimated by determining the extent to which there was agreement between the posteriors for eight propositions concerning effect size. These propositions ranged from a negative effect of >25% reduction being very likely to a large positive effect of >25% increase being very likely. Of 76 bird species recorded and nine species of mammals captured, there were sufficient data for analysis of 21 bird species, five ecological groups of birds, and five mammal species. The bulk of the classical tests were of low power; of the 99 species/microhabitat combinations tested, only 10 were significant at the 0.05 level (12 at the 0.1 level). The standard classical analysis allowed few conclusions other than the data were uninformative. The Bayesian procedure was more informative. For 68 species/microhabitat combinations, there was consensus among the posterior distributions for one or more of the propositions about effect size. The Bayesian analysis indicated that, over the entire study area, negative effects were not likely to be greater than the degree of canopy opening. However, in the microhabitats that received most of the damage, negative effects were likely for far more species.
Agroecology offers a scientific and operational framework for redesigning animal production systems (APS) so that they better cope with the coming challenges. Grounded in the stimulation and valorization of natural processes to reduce inputs and pollutions in agroecosystems, it opens a challenging research agenda for the animal science community. In this paper, we identify key research issues that define this agenda. We first stress the need to assess animal robustness by measurable traits, to analyze trade-offs between production and adaptation traits at within-breed and between-breed level, and to better understand how group selection, epigenetics and animal learning shape performance. Second, we propose research on the nutritive value of alternative feed resources, including the environmental impacts of producing these resources and their associated non-provisioning services. Third, we look at how the design of APS based on agroecological principles valorizes interactions between system components and promotes biological diversity at multiple scales to increase system resilience. Addressing such challenges requires a collection of theories and models (concept-knowledge theory, viability theory, companion modeling, etc.). Acknowledging the ecology of contexts and analyzing the rationales behind traditional small-scale systems will increase our understanding of mechanisms contributing to the success or failure of agroecological practices and systems. Fourth, the large-scale development of agroecological products will require analysis of resistance to change among farmers and other actors in the food chain. Certifications and market-based incentives could be an important lever for the expansion of agroecological alternatives in APS. Finally, we question the suitability of current agriculture extension services and public funding mechanisms for scaling-up agroecological practices and systems.
A post‐hoc study of the influence of dietary fatty acids of the n‐3 and n‐6 series on the growth of the prawn, Penaeus monodon showed a clear example of interaction by these nutrients to influence growth. Data from three independent growth studies examining the dietary requirements for linoleic (LOA, 18:2n‐6), linolenic (LNA, 18:3n‐3), arachidonic (ARA, 20:4n‐6), eicosapentaenoic (EPA, 20:5n‐2) and docosahexaenoic (DHA, 22:6n‐3) acids were standardized through a common reference to allow comparison. Analysis of the variation within the experiments was able to define effects attributable to the individual experiments or the overall dietary n‐3 and n‐6 levels. A generalized additive model (GAM) indicated that both parameters (experiment, and n‐3 and n‐6 levels) had significant (P < 0.05) effects on growth. Loess nonparametric modelling of the data clearly demonstrates `the effect of relationship' on prawn growth to the levels of dietary n‐3 and n‐6 fatty acids. The response surface model shows clear effects of both n‐3 and n‐6, and that the effect of n‐3 changes with the level of n‐6 (and vice versa). Parametric examination of the relationship (y=–37.149x3 + 160.84x2 – 118.64x + 290.6, r2=0.492, P < 0.05) between growth and the ratio between the two fatty acid classes suggested that the optimal ratio of n‐3 and n‐6 fatty acid is about 2.5 to 1. The results of this study demonstrated that the interaction of the dietary n‐3 and n‐6 fatty acid classes is an important factor of prawn fatty acid nutrition.
Valuing Diversity in Animal Production Systems the resilience of APSs to market price fluctuations and climatic shocks. However, the need for new technical skills and sometimes high initial investments can act as strong inhibitors of farm diversification. We conclude with a description of some of the research or action that is needed for these principles to be more widely implemented in commercial farms.
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