Daily Water Intake by Common Marmosets (Callithrix jacchus) and Recommendations Regarding Fluid Regulation

Abstract

The typical daily water intake of common marmosets (Callithrix jacchus) in a research setting has not been well characterized. Because these New World primates are in demand as animal models for neurobehavioral experiments, which can include the potential use of fluid regulation for training, veterinary and research staff need to understand how marmosets keep hydrated under normal circumstances. In the current study, we measured the water consumption of older (age, 5 to 12 y; n = 11) and younger (age, 1 to 2 y; n = 11) marmosets every 3 h during the 12-h light phase in 2 different months (January and July). The overall daily water intake (mean ± 1 SD) was 61.3 ± 20.4 mL/kg (range, 36.3 to 99.0 mL/kg); water intake by an individual marmoset or cohoused pair was fairly consistent from day to day. Water intake did not change across the four 3-h periods measured during the day, and minimal water was consumed overnight when the room lights were off. In addition, daily water intake did not differ between the 2 mo of measurements. Older animals drank significantly more than the younger group, and weight was directly correlated with water intake. Water intake was not affected by body condition score or housing status. The variation in water consumption among marmosets underscores the need for individualization of fluid regulation guidelines.

Figure 1.

Daily water intake (mL/kg; mean ± 1 SD) for singly housed, pair-housed, and mixed housing cages of marmosets (mean ± 1 SD). The water intake of a pair is divided by their combined weight to determine individual daily intake. Mixed 1 refers to one animal housed alone in January and paired in July; Mixed 2 refers to 2 animals that were pair-housed in January, but only one animal was left in July. Single 1 and Mixed 1 are considered outliers and were removed from subsequent analyses.

Figure 2.

Water intake (mL/kg; mean ± 1 SD) of study marmosets for each time period during the day (0700 to 1000, 1000 to 1300, 1300 to 1600, and 1600 to 1900), and night (1900 to 0700). One-way ANOVA (F_4,50 = 6.591, P < 0.001) followed by Tukey posthoc testing (*, P < 0.05; †, P < 0.01, and ‡P < 0.001).

Figure 3.

Average daily water intake (mL/kg) of younger (1–2 y, n = 10) and older marmosets (5–12 y, n = 5) represented in a box-and-whisker plot. Whiskers extend down to the 10th percentile and up to the 90th percentile. Mann–Whitney test, P < 0.01.

Figure 4.

Average daily water intake (mL) of study marmosets (n = 15) according to weight (kg); members of a pair were included only when their weights were within 40 g of each other. Pearson correlation (r = 0.76, P < 0.001) with regression line (y = 145.4x – 31.81, R² = 0.58; P < 0.001).

Figure 5.

Daily water intake (mL/kg; mean ± 1 SD) of study marmosets according to BCS (BCS 2+, n = 4; BCS 3 or 3+, n = 7; BCS 4, n = 2 [no SD]). Members of a pair were included only when both had the same BCS. Kruskal–Wallis test, P = 0.84.

Figure 6.

Daily water intake (mL/kg; mean ± 1 SD) of study marmosets according to housing status: singly housed, n = 3; pair-housed, n = 16. The water intake of a pair is divided by their combined weight to determine individual daily intake. Mann–Whitney test, P = 0.28.