Water turnover was measured by tritium dilution in 3 groups of 8 growing pigs receiving different amounts of the same diet for 9 weeks. Control pigs (ration R1) were fed 47 g/kg bodyweight initially (about 10 weeks of age, 27.8 kg liveweight), gradually reducing to 34 g/kg at the end of the experiment (about 19 weeks of age, 68.6 kg). During the same period, a second group of pigs were fed ration R2, consisting of 42 g/kg initially (28.7 kg liveweight), reducing to 30 g/kg (68.2 kg); the third group received R3, consisting of 39 g/kg (30.6 kg) reducing to 25 g/kg (59.0 kg). There was no difference in overall efficiency of feed conversion among pigs fed the three levels of feed. However, daily weight gain for the R2 and R3 pigs was significantly lower than that of the control pigs (R1). Water turnover rates (ml/kg and ml/kg0.82) for R1 and R2 pigs were similar in value and also in pattern, tending to decrease throughout the study. R3 pigs showed a continuous increase in turnover rate, suggesting the gradual development of an over-drinking (polydipsia) behaviour. The extra water intake was apparently not for homeostatic purposes, but was probably motivated by hunger. It was evident that pigs showed polydipsia when the daily DM feed intake decreased below 30 g/kg bodyweight.
|Publication Title||Applied Animal Behaviour Science|
|Author Address||Dep. Animal Science, Univ. Alberta, Edmonton, Alta., Canada T6G 2H1.|
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