Productivity of Bedouin goats: Coping with shortages of water and adequate food

The study was carried out under outdoor summer conditions on goats that were watered only once every four days and goats that were watered once daily. Under each of the watering regimes the goats were fed on alfalfa hay (a high quality roughage), and Rhodes grass and wheat straw, medium and low quality feed respectively. In all trials except one, the goats maintained constant body weights. When goats were watered infrequently they gulped down volumes of water that often caused the osmolarity of the rumen fluid to drop from 360 mosm/kg to about 80 mosm/kg. Over this entire range of osmotic concentration the bacterial populations in the goats' rumen maintained their viability. By reducing the fluid flow through the gut, infrequent drinking helped to extend the time the digesta were retained along the digestive tract. As a result, digestibility of the roughage, particularly that of the low quality feed, was improved. Infrequent drinking was found to reduce the animals' demand for metabolizable energy and, as a result, enabled the goat to balance its energy metabolism on a low energy intake. It also improved the balance in the utilization of dietary protein while not interfering with the ability to recycle urea. It is concluded that the effects of the two deficiencies dealt with in this study are by no means additive. Frequent watering of ruminants in the desert is likely to increase their demand for food, lower their gain in digestible energy, increase their demand for metabolizable energy and make it more difficult for them to balance their energy budget. Improving feed quality for animals grazing in the desert, when water availability declines, is also not advantageous. It may only increase the animals' needs for water, render them dependent on frequent drinking and restrict their grazing area to the close vicinity of water sources. 30 refs, 10 figs, 6 tabs