The rearing of domestic animals may have significant environmental effects. Effluent from waste lagoons associated with concentrated livestock feeding operations can serious water pollution problems. Goats and sheep have destroyed pastureland in the Near East, Northern,Northern africa,Portugal and Spian. Of particular concern are the environmental effect of raising cattle. Significant amounts of forest land have been converted to marginal pasture land to raise beef. Production of one pound of beef requires about four times as much water and four times as much feed as does production of one pound of chick. An interesting aspect of the problem is emission of greenhouse-gas methane by anaerobic bacteria in the digestive system of cattle and other ruminant animals; cattle rank right behind wetlands and rice paddies as producers of atmospheric methane. However, because of the action of specialized bacteria in thier stomachs, cattle and other ruminant animals are capable of converting otherwise unusable cellulose to food.