Introduction
Genetic engineering  of microorganisms to increase rumen productivity in developing countries is being investigated in recent times. Fibrous feeds and cereal crop residues of low digestibility comprise the major proportion of feed available to most ruminants under small holder conditions in developing countries. In this context, the primary objective  of the manipulation  of rumen organisms must be to increase the rate and extent of digestibility of these fibrous feeds as this is a primary limiting factor. Because of feeding of ruminants with the feed of low digestible fibrous feeds, productivity of these livestock has been extremely low typified by low growth rates, late maturity, low reproduction rates, late maturity, low reproduction rates, low milk yield and stunted mature body size. The low productivity can be overcome to some extent by supplementation to ensure that:

Understanding the factors controlling rumen microbial activity may allow scientists to modify the rumen ecology in order to create conditions that will optimize the use of poor quality feed by ruminant livestock. The fastest way to improve rumen function in an animal is to introduce digestion-enhancing bacterial species from other animals or to selectively increase populations of species that inhabit the rumen only at low levels.

Rumen ecology may also be modified by altering the function of bacteria using genetic engineering techniques. Many approaches have been taken in attempts to transform rumen bacteria by introducing a foreign gene or genes into the bacteria.