Water requirement of food producing and companion animals.

In contrast to other essential nutrients there are only few publications de aling with the water requirement of food producing and companion animals. T he exact derivation of water requirement and more detailed knowledge about the actual water consumption of each animal is only required if water suppl y is limited or too expensive to be provided in abundance, in case of limit ed water supply the water requirement is of special interest in order to pr event negative effects on animal health, performance or welfare. Intentions for water restriction or reasons for an accidental reduced water intake ar e quite different and Variable in animal husbandry or keeping of companion animals. The following conditions only represent a few examples: water rest riction in order to keep the litter dry (for example in poultry houses), du e to technical problems concerning water supply like blocked-up waterers or failure to estimate the water requirement correctly (e.g. pet rabbits fed on concentrate and carrots without any additional water). Water consumption measured under conventional housing conditions tin litre per kg dry matter intake) varies in a wide range (from < 1 : 1 up to > 4 : 1) from one speci es to another. With higher performance leading to increased feed intake, wa ter consumption usually also rises, For this reason it is very useful to ca lculate water consumption in relation to dry matter intake only. Besides th ere are several other factors of practical concern that have great influenc e on water intake: environmental temperature, intake of nutrients, that mus t be eliminated via the kidneys (e.g. electrolytes, nitrogen), as well as t he amount of water spent for certain products like the sweat in horses or c ow's milk, The importance of adequate water supply is best understood regar ding the consequences of water deprivation (reduced feed intake, concentrat ion of urine, impaired thermoregulation, reduced renal excretion of metabol ic waste products, intake of other fluids that may be critical with regard to hygiene, behavioural problems). Because of the consequences of an inadeq uate water intake for animal welfare - last but not least - legislation on keeping animals provides guidelines for water supply that are controlled (a mong others) by Veterinary administration.