Livestock wastes can be important sources of nutrients for crops, but manure must be managed properly to prevent loss of nutrients to the environment. One method of stabilizing manure is anaerobic digestion, a microbe-mediated process carried out in the absence of oxygen that breaks down the complex organic compounds in the manure into simpler compounds. The process results in the production of renewable energy in the form of methane-rich biogas.
Directed modification of the gene complement of a living organism by such techniques as altering the DNA, substituting genetic material by means of a virus, transplanting whole nuclei, transplanting cell hybrids, etc. [AGROVOC] [NALT]