The third of the four compartments of the ruminant stomach. Omnivores Animals that feed on material of both plant and animal origin. Onchocerciasis Infection with Onchocerca a genus of filarial worms, some members of which encyst in the tissues of animals. Subcutaneous nodule containing masses of the nematode Onchocerca volvulus. Oncogene A gene which codes for a product which causes transformation of a normal cell into a cancer cell.
Oncogenes are slightly changed equivalents of normal cellular genes called proto-oncogenes.
Oncomiracidium Ciliated larva of a mono-genetic trematode. A statistical test of a hypothesis in which the rejection region is wholly located at one end of the distribution of the test statistic. A problem orientated approach to agricultural research that begins by diagnosing the conditions, practices and problems of particular groups of farmers. Once the problems are identified a research programme is designed to address them. A key part of any such programme is conducting experiments on farmers fields under farmers conditions and management.