Microencapsulation techniques have been developed and refined for many years. However, in recent years, great strides have been made in controlling the microcapsule size down to the nanometer range when necessary. Progress has also been made in controlling the ratio of wall/capsule and the distribution of microcapsule diameter size in the batching of the capsules. One area of application for microencapsulation is the convenience of dosing large groups of animals once with a sustained-release dosage form rather than with repeated administration since this involves greater effort at animal management. For example, targeted dosages can be achieved by a specialized drug delivery system. Since animal systems are varied and ruminant animals have a digestive system that is different from and more complex than that of other animals, oral administration of a drug substance to be retained through the rumen to the abomasum for subsequent dissolution and/or excretion may be affected by a microencapsulation process. Miller and Gordon of USDA achieved this for control of fecal breeding flies by systemic retention of a microencapsulated pesticide drug into the manure. Perhaps one of the most challenging areas is that of pharmaceuticals. There is now considerable interest in the area of microparticulate drug delivery systems. Examples of how desirable nutritional properties and taste preference are achieved and how these provide improved animal products will be discussed. Additional areas of interest and some possible future systems that have advantages over conventional systems will be discussed.(ABSTRACT TRUNCATED AT 250 WORDS)