Metabolic Effects of Infrequent Drinking and Low‐Quality Feed on Bedouin Goats

The combined effect of infrequent drinking and poor feed quality on water economy and energy metabolism was investigated in Bedouin goats indigenous to the extreme deserts of the Middle East. Goats maintained under midsummer conditions were watered either once every 4 d, or once daily. Under each of the drinking regimes, they were tested on three diets: high—quality roughage (alfalfa hay), feed of medium quality (dry Rhodes grass) and low—quality feed (wheat straw). Goats maintained constant body mass in all trials except when maintained on wheat straw and watered once a day. Infrequent drinking as well as feed of low quality each independently reduced water requirement of the goats. When on alfalfa hay, goats watered once daily consumed an average (± 1 SD) of 248 ± 21 mL°kg— ⁰ . ⁷ ⁵°d— ¹. The combined effect of infrequent drinking and a diet of wheat straw resulted in a water consumption of only 93 ± 10 mL°kg— ⁰ . ⁷ ⁵°d— ¹. Gross energy (GE) intake on high—quality roughage was higher than on low—quality feeds. Infrequent drinking hampered feed intake more markedly on the high—quality feed than on the low—quality ones. On alfalfa hay, daily GE intake of goats watered daily amounted to 1496 ± 43 kJ°kg— ⁰ . ⁷ ⁵°d— ¹ and to only 901 ± 26 kJ°kg— ⁰ . ⁷ ⁵°d— ¹ in those watered once every 4 d. On Rhodes grass a GE intake of 828 ± 70 kJ°kg— ⁰ . ⁷ ⁵°d— ¹ vs. 699 ± 58 kJ°kg— ⁰ . ⁷ ⁵°d— ¹ was measured, and on wheat straw the GE intake for the two regimes was: 532 ± 72 kJ°kg— ⁰ . ⁷ ⁵°d— ¹ vs. 416 ± 57 kJ°kg— ⁰ . ⁷ ⁵°d— ¹. Digestibility of the high—quality feed was higher than that of the low—quality one. When the goats were watered infrequently digestibility increased to a greater extent on low—quality feeds than on alfalfa hay. Infrequent drinking and low—quality feed, each independently, resulted in a decrease in the resting metabolic rate of the goats. When the goat was watered once daily and fed alfalfa hay, its O₂ consumption was 724 ± 14 mL°kg— ⁰ . ⁷ ⁵°h— ¹. O₂ consumption rate was only 54% of this when the goats were fed on wheat straw and watered once every 4 d. We conclude that infrequent drinking increases feed digestibility and reduces the animal's demands for metabolizable energy, and may thus help Bedouin goats balance their energy metabolism when nutritional conditions in the desert deteriorate.