Daily Drinking Patterns and Drinking Response to Angiotensin II in Young and Adult Budgerigars Melopsittacus undulatus

Abstract

Young (2 to 3 months old) and adult (more than 8 months old) Budgerigars (Melopsittacus undulatus) were purchased from a pet shop on April 5 and May 5, 1984, respectively. The daily water intake of both groups of budgerigars was observed for 13 to 14 months following the date of purchase and an examination was made of the dipsogenic action of angiotensin II (AII) on each group.1. A peak in drinking activity was observed 1hr before and 1hr after the light was turned off at 2 weeks and 6 days following purchase in the young and adult specimens, respectively. However, after 4 to 5 months following purchase, two peaks in the drinking patterns could be observed in both groups: one soon after turning on the light and the other, 1hr before turning off the light. These drinking peaks were more prominent in the young than in the adult Budgerigars. They became less evident in June, 1985 in both groups.2. No significant correlation was found between daily drinking patterns and changes in daily humidity.3. The mean percentage of the number of birds drinking per hour in the daytime was 38.9 (young) and 14.3 (adults) at 2 weeks and 1.5 months following purchase, respectively, indicating that young Budgerigars drink once every 2 to 3hrs and adult once every 7hrs. Thereafter, the percentage increased beyond 50 in both groups, indicating that all the birds drink at relatively short intervals (about once every 2hrs). The percentage was always higher in the young groups, meaning that the young birds drank at shorter intervals.4. The mean amount of daily water intake was 1 to 2ml/bird at 2 weeks and 1.5 months after purchase in young and adult birds, respectively, and increased gradually to 3 to 3.3ml/bird at about 7 months (November, 1984) and 10 months (March, 1985), respectively. This increased level continued up to June 11, 1985 in the young. In the adults, water intake decreased from March to about June, 1985. The mean amount of daily water intake was always greater in the young.5. A significant correlation was found between the mean amount of daily water intake and mean daily humidity in both groups.6. The percentage of water ingested in the day to the total daily amount was less than that drunk at night at 2 weeks and 1.5 months in the young and adult groups, respectively, but thereafter this tendency was reversed. In any one month, the percentage in the young always exceeded that in the adults.7. Following a single intraperitoneal injection of 10μg/100g of AII, more than 50-100% of the young responded by drinking, but only 0-71.4% (usually 12-40%) of the adults did so. AII was more dipsogenic in the young than in the adult birds.