The effect of water deprivation upon the rumination behaviour of housed sheep

The importance of water for the function of the reticulo-rumen has been stressed by the classic work of Schalk & Amadon (1928). The aspiration theories of regurgitation of Chauveau & Toussaint (Toussaint, 1875) and of Wester (1926) differ, but both imply that before rumination can proceed normally there must be a sufficiency of fluid in the reticulo-rumen. However, Kick, Gerlaugh & Schalk (1937) noted that, with cattle, rumen contents which were so firm as to be almost impossible to break up by hand did not prevent rumination. The writer has noticed a similar phenomenon in sheep. In both cases the animals were given a high level of roughage and a low level of concentrates in their diet. But, even if apparently firm ingesta can be regurgitated, it is still likely that the regurgitate is in fact of a fluid consistency and therefore water intake will be a limiting factor. Transport of ingesta in suspension from the reticulo-rumen through the omasum likewise requires an adequate supply of water.