Table 52.1.

Basic Biological Parameters of Gerbils

Chromosome number	44
Life span (years)	2–5
Number of mammary glands	4 pairs: 2 thoracic, 2 inguinal
Birth weight (g)	2–4
Mature body weight (g)	65–100 (males)
	55–85 (females)
Body temperature (°C)	37–38.5
Dental formula	2 (1/1, 0/0, 0/0, 3/3)
Food intake (g/day/100 g weight)	5–7
Water intake (ml/day/100 g weight)	4–7
Urine volume (ml/day)	Few drops to 3–4 ml
Heart rate	260–600
Respiratory rate	70–120
Sexual maturity	9–12 weeks for both sexes
Estrous cycle	4–6 days; postpartum estrus is present
Gestation	24–26 days
Number of litters in lifetime	6 or more
Litter size	1–12 (average 5)
Eyes open	16–20 days
Weaning	21–24 days

(Adapted from Clark, 1984; Field and Sibold, 1999; Harkness and Wagner, 1983).