| Popis: |
Growing pigs do not show, in their watering behaviour, a direct response to systemic water requirements. At environmental temperatures around 25° C, growing pigs have a daily water turnover (measured by tritiated water) of 120–130 ml/kg or about 250 ml/kg0·82 when fed dry pellets at the rate of 4–5% of body weight daily. Water intake was unchanged or slightly decreased when food intake was allowed to increase. Both reduction of food supply to half its usual amount, and fasting, significantly increased drinking and water turnover rate. The pigs, therefore, consumed more water when food was restricted; a behaviour attributable to hunger. The concept of overconsumption was supported by studies of responses to replacement of normal drinking water by quinine or sucrose solutions. Drinking of water was abolished when the normal amount of dry pellets was mixed with two parts of water (a total of 71% water) and offered to the pigs at an environmental temperature of 32° C. Drinking returned, however, when wet food (71% water) containing inadequate dry solids equal to only 2–3% of body weight daily, was provided. Behavioural observations and the turnover studies with tritiated water both suggest that water for abdominal fill was taken during the afternoon. The high water turnover rate of pigs and their reduced discrimination of water from food accord with adaptation to the wet habitats in which pigs evolved. |
