Abstractad libitum water intake patterns in newly weaned pigs were investigated, with particular emphasis on the impact of water quality, the presence or absence of food antibiotics and the use of water soluble probiotic. Pigs were given water containing low (217 mg/l), medium (2350 mg/l) or high (4390 mg/l) levels of total dissolved solids (TDS), either with or without a water additive containing probiotic, and a medicated (experiment 1 and 3) or unmedicated (experiment 2) starter diet for 20 (experiments 1 and 2) or 5 (experiment 3) days immediately post weaning. Water intake, food intake, growth and faecal scores were recorded, and blood was sampled to determine ionic composition. There appeared to be two phases of water consumption: intake in the first 5 days post weaning did not appear to be related to apparent physiological need, whilst later, water consumption increased in parallel with food intake and body-weight gain. In the earlier period, behaviour may have been a primary influence; water intake was not related to faecal scores and water quality had no effect on consumption. In the later phase, intake increased at higher TDS concentrations. Water quality had no effect on performance when pigs were given medicated food; however, pigs receiving unmedicated food exhibited reduced gain (P > 0·05) and food efficiency (P < 0·05), and increased incidence of diarrhoea, when consuming water with elevated mineral levels. The probiotic did not improve performance or decrease scouring (P > 0·05). Blood composition was not affected by treatment (P > 0·05). Although physiological need may be fundamental in establishing water requirements, it appears that other factors such as water quality and the process of weaning influence consumption patterns. These data provide further encouragement for research to define true requirements for water, which by necessity would require identification of all mediating factors.

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