Conclusions

The spreadsheet described and attached to this document provides a framework for calculation of the fossil energy use in various animal production systems, using the widest definition of the term. That is, a production system here is regarded as the sum total of the inputs (including the cropping systems used to provide feed) all the way to a product that has been prepared and is ready for consumption. A limited number of systems have been analyzed, but the model has the flexibility to accommodate many more. Default values for all parameters, obtained from the literature, are included. These should only be used with great caution, as in all cases actual local data are much preferable. Under the default systems examined, livestock production (in the narrow sense) is the largest component of the whole, and of this the energy embodied in feed is the largest part. Therefore, improvement in the efficiency of fossil energy use for production of food products of animal origin should be most easily accomplished by increasing the productivity of the livestock component. The most important part of the livestock component is the feed requirement, so that attention should be given to a) increasing the energy efficiency of feed production (including greater use of byproduct feeds); and b) increasing the efficiency of feed utilization by animals.

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