AVOTAN,(+) avoparcin is a glycopeptide antibiotic manufactured by Cyanamid (UK) via the fermentation of a strain of Streptomyces candidus. The gross energy requirement of manufacturing avoparcin is calculated and compared with the gross energy savings of feed utilisation when used in animal feeding regimes for broiler chickens, pigs, beef cattle and dairy cows for milk production. Avoparcin improves farm animal production in terms of liveweight gains and feed conversion efficiency. So, by conserving animal feed it conserves the energy which would have been expended to produce that animal feed. The energy savings thus calculated range from one to two orders of magnitude on an energy ratio basis and so are very significant. The widespread use of avoparcin in world agriculture is therefore very beneficial in an energy conservation context.