A conceptual approach to design livestock production systems for robustness to enhance sustainability

摘要

Existing approaches to enhance sustainability of livestock production systems focus on the level of sustainability indicators. Maintaining the level of sustainability in the face of perturbations, which is robustness of sustainability, is relatively unexplored. Perturbations can be classed as noise (common in a specific system environment). shock (uncommon, either in occurrence, magnitude or duration), cycle or trend. Livestock production systems are hierarchical structures of nested systems. Lower system levels are from the biological and ecological domains (animals and micro-organisms), intermediate levels are predominantly from the technical domain (pen, barn and herd) and higher levels are from the social domain (production chain, livestock production sector). Resilience theory is the model for maintaining system features in the presence of perturbations in ecosystems and social systems. It is merely a descriptive approach, due to the low level of design and human control in these systems. Robustness theory is an equivalent model to describe and understand the maintenance of system features in biological and technical systems under perturbations. Additionally, robust design theory distinguishes concept design (choice of concept, components and materials). parameter design (optimal configuration of control factors given the concept design) and tolerance design (eliminating causes of variation) to deal with perturbations and their effect on the system. Technical systems of current livestock production systems are heavily based on tolerance design, but an interesting opportunity for new designs is to utilise the animal's intrinsic adaptation capacity and incorporate concept design and parameter design for over-all robustness. Concept design strategies for robustness include diversity and heterogeneity of components, functional redundancy and modularity. A fourth level of design, called hierarchy design, is needed to ensure that higher system levels support lower system levels of livestock production systems for optimal robustness. To enhance over-all robustness of livestock production systems for sustainability, a specific approach is needed for each system level and these approaches should be integrated and balanced