Rabbits given an excess of air-dry food but only small amounts of drinking water had a lower food intake and lost more weight than those given food and water freely. They lost weight because they had less digesta in the gut and less water in the skin, and had catabolized more tissue. Their response to water shortage was similar to that seen in other grazing mammals. With low food intake, gut contents fell and the digestibility of food rose, while the daily mass of and water loss in faeces fell; the moisture content in faeces remaining the same. Dehydrated rabbits produced relatively small amounts of urine, up to 1.9 M urea, which was twice as concentrated as that of rabbits given water freely. The rabbits were not able to reduce their requirement for water to less than 55% of their total intake of food and water. As pasture species in mediterranean-type environments become relatively dry in summer and contain only 10 to 5% water, a shortage of water in natural pastures in those areas may, therefore, limit the amount of food which rabbits can use, and the ability of rabbits to survive in summer would, therefore, depend upon the availability of succulent, drought-resistant perennial vegetation.
Increasing food intake affects digesta retention, digestibility and gut fill but not chewing efficiency in domestic rabbits (
Oryctolagus cuniculus
)
