Gross energy digestion and urea recycling in the desert black Bedouin goat

1. 1. Gross energy digestion and urea recycling were measured in Bedouin goats inhabiting extreme deserts in the Middle East and compared to Swiss Saanen goats. 2. 2. The apparent gross energy digestibility of alfalfa hay and wheat straw in the black Bedouin goat were 6% and 33% respectively higher than in the Swiss goat. 3. 3. When the amount of alfalfa hay fed was restricted to about 60-70% of the ad lib consumption, recycling of urea in the Bedouin goats was maintained at rates (0.44g·N-urea [kg·day]^-1) similar to those recorded when alfalfa hay was fed ad lib. In the Swiss goats a 30% drop was recorded. 4. 4. When wheat straw was the only feed, the amount of urea recycled by the Bedouin goats (0.18 g·Nurea [kg·day]^-1) was more than twice the amount recycled by the Swiss goats. 5. 5. Supplementing the wheat straw to provide both breeds with equal amounts of digestible energy and nitrogen intake resulted in an increase in the amount of urea recycled in both breeds. The Bedouin goat, however, still recycled twice as much urea (0.3 g·N-urea [kg·day]^-1) as the amount recycled by the Swiss goats. 6. 6. It was concluded that under adverse nutritional conditions the Bedouin goat possesses high potentials to both meet its caloric demands as well as to economise its nitrogen metabolism and the two characteristics are complementary to each other.