Interrelationships between feed quality, digestibility, feed consumption, and energy requirements in desert (Bedouin) and temperate (Saanen) goats.

Intake of high quality roughage (alfalfa hay) by black Bedouin goats was lower than by Swiss Saanen goats. Bedouin goats have lower energy requirements and less tendency to accumulate solids. Apparent dry matter digestibility was higher in Bedouin than Saanen goats even when high quality hay was offered. It was more pronounced when a medium quality roughage (Rhodes grass mixed with alfalfa) was fed. Differences in apparent digestibility of dry matter were greater when a poor quality feed such as wheat straw was offered. Similar differences between the two breeds were noted in relation to the apparent digestibility of cell wall constituents (cellulose, hemicellulose, and lignin) and nitrogen. When medium quality roughage was fed, Bedouin goats apparently consumed enough energy to sustain both maintenance and production, whereas Saanen goats consumed only enough to maintain very low production. Bedouin goats maintained their body weight and solids on an energy intake up to 50% less than the estimated maintenance requirement of goats, whereas Saanen goats lost body weight and solids. It is suggested that reduction in metabolic rate helps desert ruminants cope with chronic energy shortage.